2009 Jeep Wrangler Misfire Cylinders 2 & 5

2009 jeep wrangler 3.8l v6 6speed manual with a dead misfires on 2&5
found no spark from #2/5 coil and a bad pcm. the pcm was damaged due to the coil primary circuit shorting and drawing excessive amperage which burnt out the coil control driver.
pcm was on backorder for at least 3-4weeks from the dealership and no used pcm was available, i even went to a u-pull-it and could not find anything.
decided to try rockauto, they had a mopar remanufactured unit in stock so it was ordered. the remanufactured pcm was not able to accept a flash, a vin write or identify itself...i used 4 different tools total....
at this point i decided to take on repairing the faulty driver. i had to invest in tooling to complete this task.
finding the replacement component was a chore due to electronic component shortages...only place to get it was from china but delayed...everything is made in china!!!
after the repair was complete the pcm was reinstalled into the vehicle, an electronic throttle control and crank position sensor relearn.
vehicle is fixed and runs perfect!!
this is the link for the mosfet i used.
www.auto-chips.com/g18n40bg-v...

[@olistia]

Worked good had the same problem in the same spot thank you for the video working on 2011 Jeep

[@edwardwoodley755]

This is an awesome tutorial! Thank you!

[@JMU_664]

Awesome video!

[@turbografxkhemikal6669]

thanks alot

[@Alanthe918mobilemechanic]

I know to program this pcm u gotta turn ur headlights on then off then ignition off then it will program thanks for the information very helpful

[@DANBRIDI]

Nice work....

[@madmike214]

Thanks Dan!

[@casper3130]

2022 and jeeps are still having missfire issues a lot like mine before 50k miles some sooner.

[@sinkinpat]

Same thing happened to mine. I didn’t have computers to diagnose. First time in 248K I took the jeep in. Too bad they can’t repair the PCM so they replaced it for $750 + coding. I got it back but I still have a misfire. I think I had multiple things happen at the same time. Now I am guessing clogged injectors or valves going. Might be time for a rebuild, or a crate motor.

[@madmike214]

If it was the same as this, having a shorted ignition coil will kill the new pcm

[@sinkinpat]

@@madmike214 , had to replace the coil too. I did not understand why a shorted coil kills a PCM. Seems like a bad design to me. Mechanic tried to tell me spark was jumping back into the wire from the PCM. But that did not seem logical. I have new coil, wires, plugs, PCM. I love my old analog jeeps. They may not be fuel efficient, but they are super easy to repair.

[@madmike214]

@@sinkinpat with a shorted coil, that mosfet becomes a fuse... it's essentially taking a path from battery positive to battery negative...

[@christoffeldorfling2304]

It looks like I might get a new IGBT transistor via someone that have contacts with supplier in USA. It will save me a lot of money.

[@christoffeldorfling2304]

@@madmike214 you right, the coil pack had a short end blow the transistor.

[@muradswati7676]

Great job. As an enthusiast, I understand the pin connections but how do you trace what mosfet it connects to? I've heard people say follow it through but I don't understand.

[@madmike214]

I'm this case it was obvious because it had a hole in it but following it through would mean locate the pin and on the board side follow the traces to and through the components

[@christoffeldorfling2304]

Good day. My name is Christo.I am in Namibia and I have the same problem. I can not obtain the reqired transister anyware. please guid me how and whers to find it. I am stranded since December. It will be muchly apriciated !!!

[@madmike214]

man!! im so sorry for the delay in reply... this is where i ordered from. www.auto-chips.com/g18n40bg-vulnerable-ignation-chips-for-automobiles-ecu-p0407-p0407.html?fbclid=IwAR3mPrVxJnsnsFI9B3rBRU3E4fQIHCZjnrTiu35Bb8seH76JwWgQEefdglY

[@ClintoniosCars]

At the end you said you had to re learn the ect. What is that and how did you re learn it?

[@madmike214]

Electronic throttle body, it's done through a capable scan tool

[@sarahhurt7302]

I have a 2009 jeep wrangler with the 3.8 replaced the coil pack 3 times because it busts. The code reader says "Cylinder 2 misfire" Replaced the plugs, wires, second fuel injector, cam shaft sensor, crank shaft sensor, bought a new computer (today). The computer and coil pack were both new when we put it on but its still doing the same thing 😫

[@madmike214]

Are you testing or just putting parts on? You need to test the coil control and make sure you have the same put of the pcm and the same at the coil. Chances are you have an openwire somewhere

[@Islandsbelizesale-ch5kk]

Hello, did you found the reason? Ang updates?

[@TXFarmRoad]

Always check all your grounds 👍🏻

[@Fastest94v6]

How can I locate a pinout of the ecu components? I am getting into repairing clusters and ecu’s but to figure out the guts of the electrical is difficult

[@madmike214]

You won't find a schematic unfortunately, only pin out you will get is for the connector then you have to internally trace the circuits

[@raulfernandez2762]

I got the same problem

[@BigfootTJ]

So you solder the pins back to the pads and have solder paste under the module? Whats the coating that goes over the chip called? I'm going to try this, worst case scenario it's still broken

[@madmike214]

Yes sir... I used solder paste and a hot air set up to remove the old one, a regular iron along with a solder wick to clean up the pads, add the paste and then the hot air to install the new one. The coating is called "conformal coating" you can get the pen version on Amazon. If you don't have a hot air station, look up "super Mario diagnostics", he actually put out a video yesterday (high quality and highly detailed) on replacing a mosfet with just an iron. Good luck and let me know how you make out!!🤘

[@BigfootTJ]

@@madmike214 will do. Thank you for the info!

[@madmike214]

Along with the conformal coating pen grab a conformal coating stripping pen as well to help with cleaning that coating off, i originally used alcohol which worked well but i still ordered a the stripper and went over it just in case...it Matt have been overkill but it was my first pcm repair and i didn't want to take any chances 😆

[@digitalbuzz]

@@madmike214 what kind of conformal did you use? acrylic or silicone?

[@madmike214]

MG Chemicals 8309-P Conformal Coating Stripper-Pen, 10 mL Felt Tip Pen a.co/d/i4qDaJg

[@JoseSandoval-ic5xe]

Hi was car running lean with those misfires also?? Was there no more misfires after repairs? thank you

[@madmike214]

I didn't check fuel trims because it was a dead miss. There was no need to check and after the repair no more misfire 👍

[@JoseSandoval-ic5xe]

@@madmike214 Awesome I had cylinder 3 coil short out and I never thought it can damage something inside PCM,thank you for your response after replacing everything on that cylinder this is my last bet thank you again.

[@adedejijaiyesimi5504]

Finally someone with same issues but better skills. Thanks for sharing. This is the second time I'll be having this issue, first time my mechanic had to swap too many parts and ended up costing too much but now i have this video! 😎😎 Quick question, is it possible to cannibalize a previous pcm to get the faulty drive? also is it possible the coil isn't the culprit(can it be caused by something else) and finally can you please explain the relearning process. 2007 Sahara Jk

[@madmike214]

Glad it may help. Yes you can cannibalize another pcm as long as you can verify the mosfet is the same or similar values...i honestly wouldn't know how to look that up, i replaced this one with a new mosfet that was identical. As long as you don't damage the one you are removing you'll be fine, i was actually going to do the same. I'd have to look at the wiring diagram again but i believe the coil is supplied a power through the asd relay and the pcm grounds/controls the coil. So it's not likely something other than the coil....but...technically...yes it's possible but you would need a short to power on one of the coil control wires for that to happen or maybe if someone used a power probe incorrectly or jumped 12v positive to the control circuit. And relearn may or may not need to be performed, it's a cam/crank correlation relearn which is done with a capable scan tool.

[@turbografxkhemikal6669]

please how can i get that fuse on the pcm

[@madmike214]

I think the part number is in the description, contact digikey.com

[@electrake2063]

NO! @ 2:20, you are WRONG. You SHOULD get about 0.6 ohms between pin 2 (common) and each of the other pins (pins 2/1, 2/3, 2/4) and you SHOULD get double that (1.2 ohms) between pins 1&3, or 1&4, or 3&4. Check your schematic later on in the video, pin 2 is common which is why it shows half the resistance. Your ignition coil was fine. So that doesn’t explain the failure.

[@madmike214]

not sure I'm following...not saying you're wrong, I'm always up to learn, the common comes from the ASD output (30 amp fused from ASD relay) supplies the b+ to each individual circuit, this is 3 series circuits with a common b+, the path to ground is different for each primary circuit, each mosfet switches the ground side and only one is active at a time. Typically with 1.2 ohms I'd expect to see somewhere around 10-12ish amps on a current ramp, when i scoped the ignition system that's what I observed after the PCM was repaired and the new coil in place (this was not filmed). 0.6 ohms would put it over 20-24 amps depending on system voltage and if it has current limiting or not, which i don't believe these have.

[@jttherealg]

What's the transistor number?

[@madmike214]

www.auto-chips.com/g18n40bg-vulnerable-ignation-chips-for-automobiles-ecu-p0407-p0407.html?fbclid=IwAR3mPrVxJnsnsFI9B3rBRU3E4fQIHCZjnrTiu35Bb8seH76JwWgQEefdglY

[@karlzzytegzzy6016]

How many transistors are there? And is all of them the same?

[@madmike214]

3 for the ignition drivers that are the same

[@karlzzytegzzy6016]

@@madmike214 thank you sir

[@danieldesrochers9220]

what the p/n of the diode

[@madmike214]

It's not a diode it's a MOSFET... Read description

[@quincysmith6894]

I Have the same problem would like to know if you have three extra that I can buy from you?

[@madmike214]

ill have to check stock but i can be reached easier through email [e-mail]

[@madmike214]

i just checked, i dont have any available, i traded away.. but this is the link i used to order them www.auto-chips.com/g18n40bg-vulnerable-ignation-chips-for-automobiles-ecu-p0407-p0407.html?fbclid=IwAR3mPrVxJnsnsFI9B3rBRU3E4fQIHCZjnrTiu35Bb8seH76JwWgQEefdglY

[@quincysmith6894]

@@madmike214 SO I ordered 5 chips was going to change 3, but the guy i had to fix it told me the bord got burnt and it can not be fixed ? WAS yours burnt?

[@madmike214]

@@quincysmith6894 slightly, cleaned up and soldered anyways

[@madmike214]

If interested i can attempt to repair it for you, i might have to bypass the pcb and run new traces. If you have pics of the board and if you're interested contact me at [e-mail] to set something up.

[@nicktubberville602]

So if they are flashing it needs a computer ? Mine are flashing except for one

[@madmike214]

If they ARE flashing then that control is GOOD, if it's not it's bad control and likely burnt the driver. Check resistance of the coil, You have to be 100% sure the coil is not shorted before you replace or repair the pcm

[@nicktubberville602]

Ok I’m getting a p2305 code and the blue/tan wire is solid not flashing the other 2 is flashing so I’m assuming I need a pcm? I have a brand new coil I haven’t installed yet I’ll install with the new pcm

[@nicktubberville602]

@@madmike214 it’s a 07 wrangler I’m assuming pcm is bad

[@madmike214]

I would test the coil first to see if that's what till it the pcm, then test the same wires for the coil at the pcm to rule out a short in the wiring. Pcm will need to be programmed

[@nicktubberville602]

@@madmike214 I replaced coil plugs and wires today tested the wires at the harness for coil all flashed except the blue/tan one then checked the wires at the pcm side and it was the same all flashed except the blue and tan one

[@MrCoachIT]

Do you remember the part number for the mosfet that you used in this repair?

[@madmike214]

I Will take a look when i get home today

[@madmike214]

G18N40BG was the part number, if interested i have a few left over $6.50ea plus shipping. took me a few months to get a lot of them from China...unfortunately that's the only place i could find them.

[@hillhobbit76]

I’m in dire need of 3. Let me know how to get this done

[@hillhobbit76]

I can’t wait as long as you had to. It’s for my work jeep. Lol