Overdrive and Speedometer HACK - 1993 Dodge Cummins D250 Truck

Part1 & Part 2 - If your computer died and you've lost your OD and Speedometer here are 2 easy work arounds to get them operational again.
Pressure Switch Part# - ACDelco 8648065 Governor Pressure Switch
DISCLAIMER!! This particular 'fix' worked on MY truck and is merely a guide to help you. It may not work on your truck. ATTEMPT AT YOUR OWN RISK. Your 1st Gen Dodge truck's wiring MIGHT be different OR you may have OTHER MODIFICATIONS.
Again - USE THIS INFORMATION AT YOUR OWN RISK AND DISCRETION!!
Thanks for watching and be sure to Like & Subscribe if you found this useful!
Links to MORE HACKS:
Double DIN Stereo Install - • 1993 Dodge Ram D250 Cu...
A/C & Pre-Heaters - • Making Your Air Condit...
Charging System - • Charging System HACK -...
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[@cowthedestroyer]

I really like that cellphone charger trick. Might give me just enough reason to swap my 90 from tbi to carbed because i want to retain the spedo and get rid of all that garb. Funny thing is that blue wire which is present on pretty much every truck since 81 is exactly what i use to swap from a lean burn system to a gm hei module. Manual for the win that has saved more headaches than i can imagine.

[@rogermadrange1724]

So awesome that you made these videos! I’m very thankful

[@johnmatarazzo1901]

WOW Thanks for taking the time for this video

[@iNVisionPrototypes]

Glad it was helpful!

[@joell439]

Always interesting. Makes me want to find an old dodge and give it new life 👍👍😎👍👍

[@iNVisionPrototypes]

Ho Joel, Thanks for watching!

[@dhillanroy8749]

Video helped me big time

[@iNVisionPrototypes]

Hi Dhillan, So your speedo came to life? Yea you can plug into the cigarette lighter then run the +ve voltage(as close to 8V as possible otherwise the speed will be off a little) down to the pickup using that tan wire with yellow tracer(unless your truck uses a different wire colour). I made mine more permanent by finding 'keyed' 12V under the hood at that black plug.

[@brettjohnson9495]

Thanks for the video. Been looking forward to seeing you work on this truck! I have a 1991. I swapped in a auto A518 O/D transmission to replace the 3 speed 727 auto. I was going to just run a switch to control the O/D… I have Pressure switch ordered now.

[@brettjohnson9495]

You only need the one wire on the pressure switch? The pressure switch is completing the ground for the circuit?

[@brettjohnson9495]

Which color wire on the O/D solenoid is in the front/rear? I started with a Napa pig tail the wires are the same color. I don’t know if it matters…

[@iNVisionPrototypes]

Yup, that's correct, only 1 wire on the pressure switch.

[@iNVisionPrototypes]

In my case front wire is blue with a (i forget the color) tracer and the rear wire was orange with a green tracer. I just tapped into the wire coming down from the PCM connector, went up to the toggle in the cab, then back down to the pressure switch.

[@iNVisionPrototypes]

As long as you keep track(ie write it down and put in your glove box) of what OG coloured wires go to new coloured wires, it doesn't matter. If you are lucky enough to find a connector with the same colours as the truck, then its a bonus.

[@dwaynehagle7445]

Yep My putter in on my garage shelf,OD is Toggled.Alternator is a one wire.Going to upgrade my speedo to ISS Pro Mechanical(Cable) A lil $$$ but it'll be done.

[@iNVisionPrototypes]

Sweet!

[@gracielag725]

Hello sir, would you have that 50 mph pressure switch part number and brand ? I really appreciate the info.

[@iNVisionPrototypes]

Hi! Call me Nick. Here's the part number for a 50PSI switch with a 1/8"NPT - ACDelco 8648065 Governor Pressure Switch. If you can please hit the like button for the video and subscribe to my channel. I would really appreciate the support. Thanks!

[@whitevanman8703]

3:19 Hi, if you want the o/d to kick in at 40mph do you get a 40psi pressure switch? If so how do you know it is going to fit in to the transmission in the governor spot? Can you give me a link to a suitable switch? I live in Ireland and no parts store here knows what a 92 D250 first gen Cummins is.

[@iNVisionPrototypes]

That's correct. 40mph may be a little low.. all depends on your rear end. I used a 50psi switch and it works like a charm. Tell your auto parts store you need an oil pressure switch for a 1980-86 TH350 transmission... that may help. Thread is a 1/8"npt If not here's a link to an ebay listing www.ebay.com/itm/122034261889?hash=item1c69cf0f81:g:zccAAOSw7M1gthny&amdata=enc%3AAQAHAAAA8GTWZ9UtCeBHRbLys8S%2FkyUIKY%2BuHScPCRWTmIBuBJdIII6hXR9MmX3rnFXbFBRAd7frePChRTUvBl3vGaPeMJuErZsc0sgVPRz1jLOk0ENokswOVDCHGEgO6sJ1oMXZxXeV%2Bnq5x3IR3%2BtGvKR0rZa6626BpyFCw1710eimz5aYCAw1FwFMCYkjrWzzBNpcii0yjbE7WkqqOOEFDlmqNsGFET1bv3l5U7ktbLVSN6yQ8SsT3p30UTy4ACknAIfum6PZfbP%2Bx%2BIpkG867mp1mCLh%2FMrjf%2FylHjj7YQFePfPCJuU%2FR%2BrdnRzzs%2BWu6lX5ow%3D%3D%7Ctkp%3ABFBMwPzaweJg

[@whitevanman8703]

@@iNVisionPrototypes Many many thanks for your help. When I said Ireland I meant Ireland other side of the Atlantic. I have only ever seen 3 American pick ups here, so asking for "an oil pressure switch for a 1980-86 TH350 in your local parts store" is a non starter. I have bought one from your link. Many thanks again for your help. My rear end is a 3:54.

[@dhillanroy8749]

I have to go outta town this weekend on 800 mile road trip with no speedo and confused on how you wired the phone charger, I’m assuming you took a 12v phone charger plugged it into 12v and ran a usb wire cut and stripped on power side going to the pickup wire?

[@iNVisionPrototypes]

See your other comment Dhillan.

[@ShaunnHerbo]

so how do i wire my od to a switch inside my cab and could i leave the overdrive switch on all the time ? or no

[@iNVisionPrototypes]

Orange green wire up from the OD solenoid on the trans, through the switch then down to the pressure switch you install into the governor port on the passenger side. It can be left on all the time(unless you need it off when pulling) b/c the pressure switch does all the work to kick the OD in and out.

[@fishiniseasy]

Have you seen another part number for this pressure switch? From what I see online it was discontinued

[@iNVisionPrototypes]

I'll give my jobber a call and see what they can cross reference

[@garyjohnson801]

Doing your transmission that way does it come out of OD on its own when you slow down or passing someone. Or do you have the turn it off when you slow down or pass someone

[@iNVisionPrototypes]

Yes, slow down or get on the go pedal to pass and the OD will drop out. Just drive like you would normally... using the governor port to control the pressure switch works like a charm. 👍

[@garyjohnson801]

@@iNVisionPrototypes thanks

[@adamvargo403]

I have a adjustable pressure switch I put on my 4x4 5.9l. Now my question is, is the orange wire going into normally open, or normally closed on the pressure switch? Also where does the blue wire go to thats on the o/d (overdrive) pigtail?

[@iNVisionPrototypes]

Hey Adam, the switch I used was a single terminal(both of the spades you see on the switch are actually one bent into a "U") normally open switch until it sees 50PSI, then it closes creating the connection and engaging the OD. The pressure switch replaces the function of the computer completing the ground for the OD solenoid. So, blue wire is hot(positive) feeds the OD solenoid - orange/green wire goes to the switch up in the cab(where I can break the connection to the pressure switch) - then down to the pressure solenoid. I would have loved to find an adjustable pressure switch - but from what I can recall my jobber didn't have one. Hope this helps. Let me know if you have more questions.

[@adamvargo403]

@@iNVisionPrototypes found a 25 to 50 psi adjustable pressure switch on Amazon. It comes with a normally open and closed terminal on it. But so far you've been a huge help. My wife will be driving this truck off and on, just maken it easier for her to drive. Last question, seen a guy take the green wire from the back of the instrument cluster and wire it direct to his vss and then ground the other side of the vss for the speedo for it to work. Is this possible?

[@iNVisionPrototypes]

@@adamvargo403 I'm not aware of the green wire from the back of the cluster. That may be another work around to get the speedo working - not sure. The way I did, I went by what the schematics showed and didn't involve pulling the dash apart(i'm lazy... lol) Glad I could help you out. If you haven't subscribed please do as it would really help me out. Thanks! And let me know how the adjustable pressure switch works out for you.

[@adamvargo403]

I am subscribed! Thabk you for te help and keep the videos coming

[@iNVisionPrototypes]

@@adamvargo403 Thanks! Will do

[@vetteguru5722]

Those old Cummins engines sound great and im not a truck guy. You sure look different in a hat. Do you sell those?

[@iNVisionPrototypes]

They do have a unique sound to them. Yes, hats are available and a new shipment of shirts are in the works.

[@mshort7087]

I swapped a Getrag 5 speed into my 93 tow truck. External voltage regulator and under hood harness from the 91 parts truck. All the stupid problems solved

[@iNVisionPrototypes]

That's great!!

[@ajkemer]

I’ve got a 92 truck has a white and orange wire and a black a blue on the speed sensor no computer how would I fix this to make speedo work

[@iNVisionPrototypes]

Play the video through and follow the process that I describe. If you get hung up in a particular spot read through the comments to see if your question has been answered. If you still have questions drop me a comment. I will try my best to answer. Thanks for watching.

[@ajkemer]

@@iNVisionPrototypesso do I need to ground the black and blue wire and put 8vdc to the other wire at the pcm connection? Thanks

[@jacobthompson4117]

Did I miss something so the orange wire ground out when it hits 50 mph does the other wire have 12v to it then?

[@iNVisionPrototypes]

Hi, Yes, the orange wire creates the ground connection to engage the OD solenoid. So, the way I set it up... +12V(blue) feeds one side of the solenoid - that's factory. Other side is an orange/green wire and rather than going to the computer to get grounded it now flows through a switch inside the cab(to manually turn off the OD when doing over 50MPH if needed), then down to the pressure switch in the governor port. When the pressure switch sees 50PSI at 50MPH it closes and grounds the solenoid. Hope this helps

[@jacobthompson4117]

@@iNVisionPrototypes okay that’s what I was thinking I wired it all up last night and it worked excellent! In my 12v cummins f100 project it’s nice to go more than 50 with out all the rpm’s

[@iNVisionPrototypes]

@@jacobthompson4117 That's fantastic! Glad to hear you got it worked out. Sorry for the late reply, it's been a madhouse here past week or so with trying to wrap up the 51 and get all the editing done. 12v in an f100.. WOW! sounds like an great project. 👍👍👍

[@thatcarguy2778]

Wouldn't a ballast resistor for a coil work too and be less problematic?

[@iNVisionPrototypes]

With such a very low draw ballast resistor won't work. Voltage drop is dependent on load experienced. We've had it set up with the cell phone charger for about 10 years. Works like a charm, no issues what so ever.

[@justacountryboy9591]

The plug at 9:04 where would the other end go I just bought a first gen and I found that same plug but can only find one end not the other any help would be greatly appreciated

[@iNVisionPrototypes]

Hi, yeah great question! That plug end that you're talking about was just sitting there not connected to anything. Notice the dirt going right out to the end on the right side(left side got rubbed clean after handling it) My thought was that was a scan tool diagnostic port for the computer(pre OBD) but was never used. Using my test light I probed it for +12VDC(blue wire) as well as ground(black w/ white tracer) to supply the transformer. Thanks for watching!

[@justacountryboy9591]

@@iNVisionPrototypes I appreciate that I thought I was missing something there but today I accomplished the overdrive and lockup switch just like you did next is getting that speedometer working any chance you can go into depth in a video of the complete install of that whole phone charger hookup deal I'm going to do the very same thing to my truck beings you just got me from a 3 speed to having what now seems like a five speed so for that I can't thank you enough and sweet first gen!!!

[@iNVisionPrototypes]

@@justacountryboy9591 Overdrive makes a huge difference in these rigs. Glad it worked out for you. I'll see what I can do about the Speedo phone charger setup. Truck is coming into the shop hopefully soon for new rockers(fenders and hood need to be blown off for that job) and I'll be doing a video on that. Biggest thing is to find a charger that has an output as close to 8VDC. Mine is just under so the speedo runs about 9kph slower than it should. Thanks for the thumbs up!!

[@rogermadrange1724]

Do you think a 5V car charger will work instead of an 8V? That’s all I have at the moment.

[@iNVisionPrototypes]

Sure, you can run with a 5v but the speedo won't show the true speed. You may have to mentally add some MPHs to what the needle is actually showing.

[@rogermadrange1724]

@@iNVisionPrototypes gotcha. Thanks

[@omarviesca2582]

Is there a specific type of phone charger you used to get 8v? Checked 2 I had laying around and they're at about 5v. Thanks

[@iNVisionPrototypes]

If I can recall correctly the one I used was 7.somthing VDC. Had it in a box with other chargers and came closest to 8VDC. You can use your 5V but the speedo will be off a little in MPH. If you have an old portable CD player(perhaps I'm dating myself) or check on ebay - should be able to pick something up there. Hope this helps.

[@youngn9na92]

What if your truck only gets up to 35mph and stays there? Does that mean I would need a 35mph switch?

[@iNVisionPrototypes]

Only 35mph? You may have something else going on. Without OD on (or the time the computer puked) my rig will get into the 65mph territory... engine doesn't sound too happy though.

[@youngn9na92]

@iNVisionPrototypes Hmm, maybe... My engine sounds fine, but a lot of the wiring harness wires going down to the transmission are pretty brittle. I replaced to tps because the tps bracket was missing when I got the truck. I'm going to check voltages to it. I'm hoping it's just out of adjustment. I just bought the truck for the engine but I want to try and figure out the transmission if possible.

[@gummyvalenzuela2509]

On my dodge the overdrive wont kick in with the toggle switch no more., i replace every sensor and even the solenoid inside the transmission., im thinking its something inside the ecm right?

[@iNVisionPrototypes]

Probably. Has anything else stopped working? Charging system? Speedo? Engine preheat?

[@gummyvalenzuela2509]

@@iNVisionPrototypes my speedometer., my alternator stoped working first like a year ago and i did the external voltage regulator thing., then my overdrive didnt work and i did the toggle switch and worked for about a year., .i checked evey wire and replaced the toggle switch., tps sensor ., and vss also solenoid inside the transmission also., and nothing., but it sure does run up to 70 mph with no problem

[@iNVisionPrototypes]

@@gummyvalenzuela2509 Do you have a pressure switch installed in the governor port to control the OD?

[@gummyvalenzuela2509]

@@iNVisionPrototypes no

[@iNVisionPrototypes]

@@gummyvalenzuela2509 There's a part number for one in the description. Throw it in follow the directions in the video and you'll have your OD back again

[@austinthomas2697]

So does the math just workout for 1psi to 1mph? Just so I am getting this right... the sensor is actually taking the transmission pressure, and at 50 psi that means the truck is at 50mph, and then it grounds itself through the switch ?

[@iNVisionPrototypes]

Hey Austin, that's correct! Sounds too easy because it is. Some guys will throw in an adjustable sensor so they can choose a pressure for the OD solenoid to kick in.

[@austinthomas2697]

@@iNVisionPrototypes Thanks so much i appreciate it! Does it matter what port you put it in ? There's a plug on mine, but it's on the opposite side of where you had yours

[@iNVisionPrototypes]

@@austinthomas2697 No problem. And yes, it's very important that you use the port I indicated - the 'governor port' which gives you the 1psi to 1mph pressure required for the sensor.

[@austinthomas2697]

@@iNVisionPrototypes would it possibly be in a different location for 4×4 trucks ? I can't seem to find it on that side up top

[@iNVisionPrototypes]

@@austinthomas2697 I'm not familiar with 4x4 transmissions but did a quick lookup on google. If you have the 46RH 4x4 here's a link with a photo shiftritetransmissions.com/shop/1990-1993-46rh-4x4-transmission-5-9l-diesel-non-lockup/ and a another link indicating the different ports www.justanswer.com/transmissions/8g938-transmissions-46rh-dodge-46rh-transmission-anyone.html On the right hand side go straight upwards from the rear of the pan you should find the governor pressure test port. Hope this helps.

[@garyjohnson801]

Wrong 2nd Gen. 1st Gen is from 1974 to 1980 and 2nd Gen is from 1981 to 1993 in the USA and 1995 in Canada. And I know because I have worked on them since new all generation until this one

[@iNVisionPrototypes]

Ok. Thanks!

[@Ramons187]

Lol first generation diesels 89-93. All the others are body styles. I know I've owned them. Love the pcm fixes! Thanks for sharing and keep up the great work! 👍 we appreciate it

[@jeffhutchins7048]

'74-'80 is a Power Wagon, NOT a RAM.

[@macklenunyo]

😂😂😂

[@conradmendosa1305]

I was told not to leave my truck in overdrive, also it has no balls in 1st when I do

[@iNVisionPrototypes]

Our trucks have loads of torque but who ever told you not to leave it in OD all the time is right! You'll lug your engine to an early death. At least throw in a manual OD switch that you can toggle from off to on once up to speed OR do the hack I showed in the video with a pressure switch screwed into the governor port.