(Pt 1) PowerStroke Power Locks DISASTER!?

[@joesmith1366]

I have a shop called the wiring guy in MT and have had 3 superdutys with same issue and wires burnt from bcm to behind rear seats to all rear doors. We have 4 locks running on an under sized wire exceeding the fuse rating and melting multiple wires together

[@joesmith1366]

We pull seats and carpet and rebuild harrness ive had it wipe out windows sunroof mirrors and all sorts of chaos when it melts the bundle

[@PineHollowAutoDiagnostics]

WOW nice to know I'm not the only one with this issue! So what is the ROOT CAUSE of this problem?? Is it the Door Lock Actuators actually shorting internally??

[@joesmith1366]

The first one we had had an aftermarket alarm that had the lock and unlock pulse set way to long. The other two were bone stock with no other issues. Cant remember the wire gauge at the moment but the wire has multiple splices and runs more then 20 ft. Possibly key fob in pocket hitting lock unlock. Or impatients and hitting buttons multiple times generating heat. In billings it gets so cold we have low voltage on batterys locks pulling more current when frozen and with under sized wires running such a distance it all adds up to higher resistance with a large fuse. Scan it and to self test on BCM there are probably more issues then locks. Harrness not available usually so it turns into a big job we upsize wire and run new to prevent future issues

[@joesmith1366]

I have pictures of everything if theres a way to send to you

[@dongningprc]

@@joesmith1366 There is Ivan's email address in the channel intro page. KZbin will ask you to click on something to prove you are not a robot though...

[@mattmaxon7783]

the fuse kept blowing and someone installed a larger fuse

[@PineHollowAutoDiagnostics]

20Amp stock fuse was already wayyy oversized 😂

[@topher8634]

Exactly what I was gonna say. My first car had no illumination on the cluster. When I checked the fuse box, there was a blown 30A fuse. You couldn't read the required size, but I knew it wasn't 30A. When I got a Chilton's manual, it showed it was supposed to be a 5A. The load side of that fuse had melted to another circuit. I had to rerun the entire illumination circuit. The short was in the ashtray light. The repeated opening and closing of it broke the wire and it was laying on the dash support and the previous owner just popped in a 30 as a "fix". It's a wonder it didn't burn down, same as this truck.

[@alansoccer2003]

Yea I'm willing to bet that's not the first time that fuse blew. Probably put several fuses in in a short period of time and it cooked it

[@_RiseAgainst]

Damn, beat me to it! Eventually the wire becomes the fuse!

[@John-dp3ln]

Or installed a no blow ‘fuse’.

[@robot5573]

Louis Rossmann had a video testing cheap fuses he bought from Amazon... and the results were really not good. I can't remember exactly but several far far exceeded their rating. Was a real eye opener.

[@kurtwinkler6859]

At 3.32 in your video you can see where the heat of the blowing fuses melted the plastic cover.

[@PineHollowAutoDiagnostics]

Good eye!!

[@greggc8088]

15:10 How? Answer with funny example-When I was a rookie at Toyota in the 90's and had a Previa blowing a radio fuse, another tech told me to "smoke test it" after frustratingly trying to find the short. Straight jumper in place of the fuse revealed the radio amp in the back quarter was the problem but sadly it smoked the harness from the fuse box all the way back. So that's the answer-Someone smoke tested that baby. LOL

[@tylerwilliams3868]

great job breaking down the diagram and locating the issue quickly !

[@marcusmohorco380]

One owner was tired of blowing 20 Amps fuses, and installed a jumper wire until smoke came out from under the trims. Then quickly removed it and passed it on to you in order "to deal with it". Problem: The harness melted together. Lucky he didn't set his truck alight. Ivan, refuse to deal with these kinda people unless they accept accountability, and are willing to bear the cost for the proper repair

[@crasher88]

get that in writing from the customer

[@fucamaroo]

Always deal with these folks. Morons like this pay the bills. Between diagnostic time and parts.... money is money

[@adotintheshark4848]

I knew someone who did the same thing to a VW Bug.."I'll see where the short is by finding where the smoke is coming from".

[@ncso911]

Exactly the issue

[@calholli]

Seeing you get frustrated and not want to keep going is kinda funny. lol.. I get that way sometimes on my own cars.. and I'll actually quit and go eat lunch or something.. And eventually I realize, "Lets just keep going, I'll keep peeling back the onion until I find out how far the melted wire goes".. and just accept what I have to do and then it always ends up being much easier than I was expecting and dreading. :) This is a fun one.

[@BLARNEYBLARNEY]

Your current drop difference … The lower current reading was going through the test light and the door coils to find its ground…. In series = more resistance/ less current. The higher reading was direct through the test lights to ground. If you rewatch your testing the side of the tree with the short is obvious. As always … great stuff

[@PineHollowAutoDiagnostics]

Take a close look at the readings... The difference was only 0.2A...so BOTH sides of the circuit were directly shorted to ground 😉

[@BLARNEYBLARNEY]

It’s three coils in parallel so the difference between a direct short and a path through the coils is small … but it is a measurable difference.

[@rodneymiddleton9624]

And the carnage continues!!!! Thanks Ivan!

[@volchip]

As my power class professor warned the students, "When you make a really bad mistake you will look out of the substation and see miles of aluminum dripping". In this case the wiring harness some of the wiring harness has been reconfigured. What a mess.

[@douglasburford8452]

The harness in these era of F series trucks are notorious for shorts.

[@additudeobx]

That wire is not 12-gauge wire. It's maybe 16-gauge or 18-gauge. Maximum current would be 10 amp. That fuse was rated too high for that circuit. It allowed constant over current thru the wire overheating it, before it melted the insulation and popped the fuse. This is an engineering design failure.

[@mattbrown5511]

Sand and other grit got into the wiring run and wore through the insulation on one or more wires. I've seen it before. As expensive as even used vehicles are, it would still be worth the cost to replace/repair that wiring harness. Great diagnosis as always, Ivan.

[@dustcommander100]

I always felt that vehicle wiring was a little overfused as compared to residential or industrial. Remember the "fusible links"? Vehicles these days have TINY wires in them, so when one ckt gets shorted to another, a tiny wire ckt can connect to a big wire ckt, so it's a mistake to run these ckts together in the same space. Looking forward to seeing how you undo this mess!

[@craiggoodwin9704]

Ivan, it looks like you have your hands full on this one. Looking forward to the next video. Thanks for Sharing! 🙃🙂

[@TheOnespeedbiker]

I have also seen fuses fail (either bad fuse or an accumulation of dust) the end result was a melted blob of a fuse that never blew. Very important to never buy cheap Chinese fuses (300 for $13.00), there is reason quality fuses like Littlefuse cost much more (40 for $25), it's because they actually blow at their rated amperage and protect your electrical system. Of course the caveat is fuses always blow for a reason, IOW the solution to a blown fuse is not to simply replace it.

[@windward2818]

Very good advice. I only stock Littlefuse and Bussmann automotive fuses from two suppliers that I know buy directly from Littlefuse or Bussmann.

[@stevenakn1]

After they seen all the smoke you got the call🎉

[@marcusmohorco380]

That's what I thought, too! Scum bags

[@leonkernan]

Considering the other comms errors, I’ll bet there’s damage to other wires further down.

[@ronaldwilkinson6685]

I've seen this on the 2003 to 2007 GM full size trucks and SUV's for the cigarette lighters and high speed circuit for the blower motor for manual HVAC. They melt the wire insulation from the inside all the way out to the underhood fuse block

[@jefferyedwards5003]

Reminds me of a story of a woman who called a locksmith because her fob died and she could NOT get in her car while she was away from home. He came, took her fob chain that had all of her keys on it and unlocked her car manually with the car key. Expensive and humbling lesson for her. We have become a society that relies to much on fallible technology and convenience. Manual door locks and roll-up windows should be wave of the future!!!

[@lieutenantdan8170]

You can keep living in the 20th century in the mean time i will be enjoying my remote started car heated up and unlocked from inside my house instead of fiddling with a key in the cold

[@jefferyedwards5003]

@lieutenantdan8170. Understand, a man with "magic legs" needs all the creature comforts that he can get. But as with this person and the fellow with the pickup who's tailgate would not open because of faulty wiring, be willing to pay the piper when they fail. Hopefully, you have a PHAD living nearby.

[@JoseSilveira-newhandleforYT]

Yikes! Overload over a long stretch of loom. Fuse must be really oversized to handle all that current and not pop. Not possible to find the origin, without removing the door panel for inspection - the problem may have started on the floor loom and found its way through the door look wiring. Part 2 should be very interesting 🙂

[@ovalteen4404]

Someone must have used a fuse that was measured in Ga rather than amps :) I guess if the body nicked the wire(s) at some point in the main harness, that's likely where the meltage will stop. Otherwise it's going through the entire length of wire and every connector back to the fuse block. At least Ford decided not to tape it up the entire way.

[@corradoferrari6191]

Short must be in the door harness where it bends when you open and close the door, some times they melt far enough that you have to remove the seats and console to fix it.

[@PineHollowAutoDiagnostics]

But I measured the resistance through the door lock circuit of the Left Rear door and it was OPEN! How do you explain that? 🤔

[@corradoferrari6191]

@ because it might have shorted to another wire not related to that ckt and created an open I have seen this many times

[@PineHollowAutoDiagnostics]

@@corradoferrari6191 so we have a bad door lock actuator AND a short in the door harness? That would be a BIG coincidence 😄

[@corradoferrari6191]

@@PineHollowAutoDiagnostics just remove the rubber acorde on on the door harness before the connector and you will see if the wires are bad which I bet they are, most likely a thicker wire with power shorted to a thinner ground wire and caused the main harness to burn the way this one is, lock fuse did not blow until power was activated to lock or unlock.

[@corradoferrari6191]

Door harness if bad can be replaced if available it was on back order for years.

[@peterouellette3874]

Have a merry Christmas to you and your family

[@major__kong]

If you have a larger wire split into 3 smaller wires, you have to fuse for the smallest wire or fuse the large wire and then fuse each of the smaller wires. But I like the theory others have said about someone just installed a large fuse when it started blowing. The previous owner of my house did that with a circuit breaker. Oh, the 15A breaker keeps tripping? Just install a 20A breaker. The real problem was the house was built in 1963 when people were using less electricity. That 15A circuit was actually powering a lot of the house. And then sometime in the 80s or 90s there was just too much stuff on it.

[@kevin9c1]

20A is too large to protect individual small gauge wires. Kind of a bad design though maybe not different than other vehicles. If the system has any kind of feedback capability, it would energize the solenoid until it sees it lock/unlock (up to a timeout I would assume). This may be a case where you need to quote the customer for a wiring harness and not try to piecemeal it. I'm sure it's expensive, if it's even available. Or used may be a better option. But I would seriously consider just doing the entire harness where wire damage could have occurred. At least quote the customer and let them decide.

[@brianw8963]

Ouch, gives new meaning to the power stroke title. 👍👍🇺🇸

[@enzop.3227]

Door harness is broken in one of the doors. If a larger fuse is used it can cause the harness to melt together and it is unobtainuim.

[@crasher88]

defiantly take the door panel off and the rubber sleeve that covers the wires that go from the door frame into the door. There could be more hidden damage

[@glenharper3136]

Thanks for the video Ivan.

[@jamesfitzgerald2361]

Time for a junkyard harness repair. He's lucky the truck didn't start on fire.I had a couple of wire fires scary stuff.

[@joevaagen6170]

I was thinking the exact same thing, not only are you fixing the original problem but also relieving any melted adjacent wires. I was thinking it had a water intrusion problem in that wire run because that would be the lowest area of the truck and if it's a Pennsylvania truck with winter snow the water has to go somewhere.

[@tomtke7351]

Pt2 -- hope Ivan finds the root cause. The long length of melted wires means long time period of over current. As Ivan noted: door lock/unlock = quite short actuation times

[@eddiereichel9354]

When I first opened my shop and was just getting into diag I had a guy bring me a VW Jetta. It had windshield washer nozzle heaters. It starte blowing a 5a fuse. He had a pile of probably 50 fuses in the floorboard. All the colors 30a 20a 15a he just kept putting them in. It melted clear back behind the dash. I did get it isolated but it still had wires melted. Id bet that your customer was putting all kinda fuses in too.

[@wernerdanler2742]

After seeing this, I think I prefer vacume operated door locks as all my previous cars have had.

[@SuperDave71176k]

If failed resistance is sending xtra current that would smelt wires.Its either a stronger current item or a small one like the door locks that would get used and repeat the occurrence often

[@SHSPVR]

long current draw can do it just under the max draw so fuse just keep on going in tell final hit 20 amps

[@RK-kn1ud]

To add to what you said...since the circuit was a long length of ~18ga wire, the high wire resistance probably regulated the current while short-circuited. Also, I only buy legit Bussmann/Littlefuse fuses now after witnessing Amazon fuses operating well above their limit.

[@russellhltn1396]

I wonder if the owner installed a eBay fuse. There's been reports the Chinese fuses won't blow when they should. One channel even pointed out that all the fuses in the kit were the same (50A?) fuse internally, just with different colored plastic.

[@kknows3512]

Power door lock delete, no parts required! Just repair the other wires damaged by this genius system.

[@phprofYT]

I wouldn't touch that harness with a 10 foot roll of automotive tape. It is full replacement or nothing. Personal opinion. By the way, that is a poor design. The wires are too small for the fuse. There was a failure to analyze what would happen if a single point of failure on one branch would create a path to ground that would draw all 20 amps through that one path resulting in an overload on the wire. If you think about it, if you need up to 5 amps on each lock then 4 x 5 is 20 amps which makes sense but with that circuit if one lock starts to short just a little bit it will draw more and more current from that circuit since they are all in parallel. The lowest resistance path draws the most current. Remember that the owner reported that at first it was only one lock that didn't work and over time it got worse until the fuses started blowing. That damage is the result of a gradual process. The circuit needs to be redesigned to either have heavier gauge wires or so no one branch can draw more than the rated current for that gauge of wire. I could get a second year physics student to figure that out.

[@TheVespap200e]

I love to see Carnage! But that is not going to be a no parts required fix Ivan! I feel bad that you have to deal with that disaster. FeelsSadMan!P.S. The moral of this story is DO NOT mess around with fuses if you don't know what your doing!

[@TheWrench97]

I currently have 2 2014 F550 from the same company in the shop with the same issue of the door lock wires in the cab harness burnt for both rear doors

[@windward2818]

Was the root cause a bad relay in the BCM?

[@TheWrench97]

@@windward2818 Not sure yet they still debating on fixing or replacing

[@joes2085]

There is a high inrush on lock solenoids. Howver, the circuit only pulses, so the wires are designed to be undersized. I'm guessing a short developed in the "unlock" circuit of that door as if someone kept their finger on the "unlock" button. That will toast the solenoid & the wire

[@Sandmansa]

Oh man, what a disaster. You can't tell me that the owner didn't smell that or see smoke. And there is no telling how many times that fuse was replaced trying to get those locks working again. How do you go about fixing this and prevent that damage from ever happening again? The factory wiring is simply not a heavy enough gauge to handle a dead short on a 20A fused circuit. Maybe replace the 20A fuse with a 10A for starters? Really, each door lock should have it's own 5A fuse. [Sarcasm] I have no idea what the engineers at Ford were thinking. If each door lock only needs 5A, why don't we just simplify the system and pile all 4 door locks on to one 20A fuse? That should work out fine, right? [/Sarcasm]

[@russellhltn1396]

Theory: The larger window power wire shorted to the door lock wiring. The locks connected to ground via the BCM when not locking/unlocking. Not enough current to pop the window fuse, but too much current for the door lock wiring. There's no fuse to protect the lock wiring from short to power, only the fuse in the power source. That kind of carnage take time, and locking/unlocking doesn't give time. So I think another circuit has to be involved. But what caused that initial short?

[@PistonBikers]

Ivan What Brand And Modelo Is The AMP Meter ?

[@PineHollowAutoDiagnostics]

@@PistonBikers see the description bro 😉

[@lorrinbarth1969]

I know what its gona take to properly fix this truck. So, time to pop some popcorn. This promises to be good.

[@10100rsn]

Yeah, 20 amp fuse looks maybe more than double the wires current rating. I'd say 5 amp fuse should be good enough but with all locks actuating together it would need a burst of at least 8 amps and a 5 amp might blow if you hold down the lock/unlock switch.

[@justinmize4316]

Get a used wire harness from a salvage yard. Lots of those trucks out there.

[@ATSNorthernMI]

I wonder if kids were pressing down on the button long enough to cause this or the BCM randomly caused a hook on the unlock or lock circuit for an insane amount of time. I would ask the customer if he randomly had a battery go dead on him from this kind of issue. BCM's in these trucks have known to cause all kinds of weird issues like lights staying on draining the battery to keeping the network alive with random gibberish that also will cause the battery to drain really fast. It seems that once you start to add a million factors involved with unlocking and locking doors, that there is a lot of room for failure. These trucks had issues with fires. Just like a lot of newer stuff just randomly burning to the ground due to issues like this.

[@mikechiodetti4482]

Whenever I found wire like that with a larger fuse, or worse a large circuit breaker, I figured like everyone else, that they thought the larger circuit fuse would fix the problem, "OR" they wanted to see where the short was located saving time by letting it burn. NOT A GOOD IDEA!

[@mikefoehr235]

I am amazed the power joke didnt become a CAR B Q. I know from personal experience, Ford has many electrical gremlins.

[@LesReeves]

I seen on an SMA video that they had tried to make the wire insulation out vegetable oil /corn sryrup & vermin like the taste maybe it is heat resistant too ?

[@michelbrown1060]

20 amps feeding a 18 gauge 18 wire will toast it easilly

[@5TheFlyingFarmer5]

My gut says the driver door hinge wire pass through has broken and shorted wires, but that's just shooting from the hip... (After watching the video that's why we test, don't guess. Data-driven diagnostics and logic)

[@JOHNSUE28]

My Gut Also says go to the Most likely stress point, And Ivan will find the source of the issue. Seen it many times.

[@georgepeck-g4h]

i am a retired truck mechanic, i had a 96 e350 ,the fuel pump shorted out and burnt the wire from inside the fuel tank to the inertia switch tn the cab ! would have been beter if it had set the truck on fire !

[@theblackhand6485]

This rally is a big disaster! Man! You just want to push this truck down your drive lane across the road and forget about it.

[@adamtrombino106]

I definitely want to see the root cause problem. Even if the circuit was over-fused, as Ivan stated, the circuit is only energized for a very short time. BUT if an actuator stuck energized, suspect lt rear door, I could see it making a toaster out of that circuit since it's over-fused. It's not yet a direct short, it's a toaster for an extended period of time.

[@CUSTOMWORKS7.3PSD]

Had a similar deal on a f350 the security module (power locks worked through this unit) shorted and had to make a new harness and rebuild the board of the security module That sucked

[@baxrok2.]

Thanks Ivan!

[@billjohnson2000]

Can you say “thermal event”? 🔥😳

[@robertheim352]

Trying to help the analysis: 1. What is the actual melting point of the insulation? 2. What current was applied that elevate the conductor to this melting point? Simple questions, but difficult to find an answer. Lets say the insulation softens (melts) at 150C and an 18 gauge wire is stressed to 20A. I predict a 125C rise in the 18 AWG copper. At 25C ambient this is close to the failure point. So maybe Ford doesn't know how to fuse a circuit?

[@dendkmac]

Something to be said for manual door locks, buddy of mine his son asked where the power door locks were pull up for go press down for lock.

[@jeffryblackmon4846]

If the wires are melted all the way to that door switch, look for a short in the door switch. as it is a passenger door, suspect a youngster who spilled a drink and failed to tell anyone about it. It's possible.

[@norcal715]

Third! Cant wait to find out where the melty harness stops.

[@kerrylewis2581]

You are the first non bot

[@brianw8963]

I got here pretty early but laid low for a while. I was afraid Ivan’s cheer leaders might drag me under the bleachers and have their way with me. I hadn’t had enough coffee yet. 😂😂

[@joecoyne5660]

There is more to the story that Ivan did not get, to burn wiring like that would require extended periods of current flow, usualy door lock/unlock circuits or active for less than a second. The only way to melt wiring like that is to have the circuit activated continously.

[@PineHollowAutoDiagnostics]

That was my thought exactly! Or pushing the button 100 times in a row haha

[@jdtractorman7445]

@@PineHollowAutoDiagnostics I was wondering that too, does he have kids that sit back there? 🤣🤣

[@CuriousB58]

Ivan you are becoming the master of the cliff hanger. Can’t wait til tomorrow… Bad door lock switch? Sticking? Causing relays to stay on extended time thus heating wires? Maybe that blew one motor to open circuit? Motor windings became the fusible link?

[@kerrylewis2581]

I never expected this amount of copper carnage for a door lock. Did someone bypass the fuse?

[@scrappy7571]

Or installed a circuit breaker....

[@stealthg35infiniti94]

I would put money the customer kept putting more and more fuses hoping that the problem would magically fix itself. The fuse is designed to protect the circuit from frying and melting like that with just one incident. I don't think he would admit to multiple fuses or even a higher amperage fuse was ever use. If a circuit blows a fuse, Stop Diagnose the problem before putting more fuses in..

[@breikowski]

Put a 12g Romex across that fuse after it blew. (The smoke was good indication where problem was)

[@scottp5331]

Yes, that's the test of maximum smoke.

[@dealerauctionnightmare4689]

A buddy bought an Altima a few years back and all the lock actuators were bad....😮😮😮😮🤣🤣

[@n6dl321]

is that a piece of warmup tape on the bcm cover bu the relay?

[@6996brandyl]

Maybe you'll find what made it shot and its cause by something the owner can turn into his insurance company and the insurance company can pay for the repair? GOOD VIDEO!!!

[@Runco990]

You are joking, right? On a 10 year old truck? We are talking INSURANCE COMPANY!

[@6996brandyl]

@@Runco990 No I'm not, if a person has full cowage on a vehicle and something cause this damage their insurance will cover it. Why pay for auto insurance if your not going to use it

[@famdesales6749]

My guess is fused popped and was replaced by a cheap online fuse that don't blow as required. Amazon is full of them.

[@russellhltn1396]

What happens if a lock/unlock switch is held down? Does the BCM limit it to just a pulse, or is it continuous?

[@windward2818]

The damage to the harness is extensive and clearly due to an over-current condition. I have only seen this when there has been some sort of event or damage where unrelated circuit wires are cross connected due to twisting or something penetrating into the harness wires. By cross connecting circuits you can exceed the current carrying capability to the point of damage of the insulation. Sometimes an object gets thrown into the bottom sheet metal, penetrates the sheet metal and into the harness cross connecting circuits. I have also seen this from someone working on a vehicle and inadvertently drilling into or nailing into a harness. Was any work being done on the vehicle when the problem started?

[@bobby9195]

Dang that's a bad short 😮 you gonna replace the harness or what? Big repair, good luck and merry Christmas 🎉

[@jimdandy2275]

Has any equipment been added to the truck where someone tapped into door harness wires for power source inside the left kick panel?

[@CajunShrek]

Lock switch got held or stuck or relay?

[@RK-kn1ud]

Is it possible that the original 20A fuse blew initially and was replaced with an Amazon fuse? I only use genuine Bussmann/Littlefuse fuses after witnessing Bezos fuses acting much higher/longer than anticipated.

[@CJRock-xn5qf]

A bigger problem now is you touched it... so now it's a personal liability issue if you don't properly repair or at minimum remove or isolate the damaged wiring. The last thing any independent mechanic needs is an underwriter suing you for damages from a burnt up truck. What if a house or other structure burns down... hundreds of thousands in damages.

[@Runco990]

YEP! It's ALWAYS the last guy's fault that touched it!!

[@richardspees841]

Wonder if the owner, in trying to fix things, put in a higher amp fuse, possible a 30 and then tried to lock and unlock multiple times?

[@dhaggy1980]

I am almost wondering if it's not the door lock issue at all. I see there are heated seats, I'm wondering if that has an issue.

[@richardmitchell7836]

Very Intersting for sure!

[@aciddiver1978]

Someone obviously replaced a blown fuse by a bigger one.

[@Carcrafter7165]

15:13 this could have been a Truck 🛻 Fire 🔥 down the road.

[@brainndamage]

Wire CSA is too small for the fuse, or the fuse is oversized for the wire. It's a bad design that's common in nearly all brands and models. Even luxury brands that cost a lot of money. They want to save money by using the smallest wire possible, ignoring the current rating of the wire. They probably think that if there is a direct short the wire resistance will be low enough for the current to be high enough to blow the fuse before melting the wire. That is only true if the short is direct, not partial, and the wire is short enough - after some length, the resistance of the circuit is too high to reliably blow the fuse even with a direct short. A partial short may melt even a short length of undersized wire, say if the wire can only carry 10A continuously, the load is normally only a couple A, but then that one wire is joined together with a couple other loads into one fuse that is, say 20A, because the total current of all loads is more than 10A. If a partial short in one of the loads occurs, so that the small wire is now carrying 20A instead of the rated 10A, the fuse will not blow, but the wire will melt if the partial short doesn't burn out in a very short time. If there is a direct short, the fuse will melt as even if there's say 40A going through the wire rated for 10A, the 20A fuse will blow before the wire melts. It's this practice of fanning out one large fuse into several smaller wires that are only sized for continuous duty for their attached load, that leads to melting wires in case of partial short (overcurrent) fault scenarios.

[@brainndamage]

The correct engineering practice that is taught to all electricians is that a fuse must always be sized for the smallest wire it is protecting, regardless of the load attached to the wire, because the fuse is there to protect the wire, not the load. If that were done in this case, the wire would not have melted. The manufacturers ignored this practice, because their product is not subject to the same regulations and inspections that building installations are, they can practically do whatever they want with wiring. You can also correct their mistake after the fact by installing smaller fuses. I do this to all my cars that I own. Look at the wiring diagrams for the load side of each fuse, look at what the smallest wire CSA is that the fuse feeds, look up the rated current capacity of that wire, then install a fuse slightly smaller than that. Of course sometimes the peak load through that fuse is larger than the fuse size you arrive at by looking at the smallest wire size, in that case you need to compromise and install a fuse that won't blow with the applied load, and gamble that there won't be an overcurrent fault on that undersized wire. The most common place where wires are undersized are blower motors, wiper motors, lights, small actuators fed by the ECU or BCM with no individual fusing other than one main fuse feeding the entire module. In the blower motor case, the inrush current when it's starting up is much higher than the normal running current, so they size the wire to the running current, but the fuse would blow with the inrush current if sized to the wire, so they oversize the fuse by 50-100% to keep it from blowing when the blower is turned on (this problem usually doesn't exist if the blower regulator is electronic, as they have a soft start current limiter).

[@JohnDoesGarage]

I see other people have said this, someone put a no-blow fuse in it to find the problem, and they did.

[@PineHollowAutoDiagnostics]

"no-blow fuse"...where can I buy some? xD

[@DaveBigDawg]

​@@PineHollowAutoDiagnosticsI heard of slow blow the no blow are the jumper wires type lol 😅

[@francoispapadakis76]

@@PineHollowAutoDiagnostics Have seen paperclips or alu-foil as "no-blow-fuse" in old MG's... 🤔

[@ncso911]

TI he owner did by putting bigger and bigger fuses in it until he burnt it up. New harness

[@Garth2011]

My guess is someone pushed the unlock button and held it on for a long time.

[@jwray9799]

owner did a fuse by-pass,,, and he thought it worked when his drivers door worked,, but it sat then and fried the harness.. so shortly after the By-Pass it finally blew the fuse.

[@malcolmcavalier7849]

You still need to remove the door panel and look inside, the connector was melting, that tells me that the problem started in the door. I am willing to bet that you did not get all of the facts about this melt down, I bet somebody is holding out on you. ( AKA handling the truth in a wreckless manner) Happy hunting🤣

[@phill3144]

I would be going straight for the drivers door loom, 99% it's the most opened door

[@stevemccauley5734]

I’d bet he has kids & one of them kept messing with the lock. Probably just held a button down until it quit. Because that fuse is too large for the circuit, the wire melted before the fuse blew.

[@65scottiedog]

Wrong fuse installed there must of been smoke in there when it happened you'll just struggle to get the smoke back in them wire ivon ,😂

[@PineHollowAutoDiagnostics]

I asked the owner if he remembered any burning smell... He didn't recall 🙄

[@65scottiedog]

@PineHollowAutoDiagnostics hum recon thanks Ivan what a great guy you are to share your knowledge.its been a real learning curve.i 58 time served hgv agri plant fitter and you've help me many a time many thanks from all in the UK have a great day and your content is 💯

[@johnt.848]

What a mess, why were'n't the wires insulated or rather, taped by the driver side? Had somebody been in there and removed the tape previously?

[@Carcrafter7165]

Looks like you’re buying a wiring for harness inside the cab. And possibly a switch.

[@HelicopterDad-u5b]

11 years old and only 250k, definitely a keeper!

[@mikedauphinais3713]

The problem is in the wire harness at where the door and body hinges

[@hikerJohn]

Get a used harness section from the junk yard

[@DependableAutoTruck]

i have a 2006 GMC 1500 that the cig lighter wires and the power outlet are both melted as far as you can see the cig lighter burned insulation completly none left on either wire