That is an epic number of fault codes. Some thoughts:

1. With all of the unplugging and testing is it possible that you started the truck with an disconnected or not fully seated connector at the ECM? Check all your plugs and wiring and clear these fault codes then see how many come back.
2. If that's not it then my guess would be fuses, Power or grounds to the ECM, a bad ECM (this is very rare), A voltage problem or a class 2 serial data bus problem
3. Does your live data ever drop out on your scanner while your hooked up and monitoring?
4. Does you system voltage ever get wonky when the truck is running?
5. Is it possible that you bent a pin(s) at the computer connectors?

George

 

No pins are bent or broken. I cleared the codes and will see what happens. I have a spare ecm programmed and ready to go if need be. I'll see what codes come up again.

 

Well I looked again today. Lots of codes popping up. Drove 10kms from my condo and the starter is gone. I'm not sure if an electrical problem could mess things up but I'll have to put a new starter in tomorrow.

 

I changed the starter and all my misfiring is gone.yay 🥳 When the caa driver came to tow me I had only drove ten kms and the truck was parked for 30 mins before he showed up and the driver said my starter was very hot. I would have never thought my starter would cause misfiring. Now I only have one code coming up and it's P0351 and its funny how it only comes back when i start the truck. If i clear it... it doesn't come back while I'm driving. I'm gonna swap out the new coil I have for the old one and see if that makes a difference. So I have a question as well. I have another pcm that is programmed for my truck but has never had a case relearn done. If I swap it out for testing purposes to see if the p0351 comes back. Can I put the orginal pcm back without a relearn ? I can't see it loosing the relearn orginal done. If that was the case it would lose it everytime the battery died. If none of the above work I have brandnew set of wires I can try. Maybe from all the misfiring and leaking wires they aren't good anymore ? Just a few thoughts. Hopefully one of them corrects the problem 😊

 

I assume that the case relearn data is in non volatile memory and should survive the ECM swap but I don't know that for sure. Maybe Les can comment.

George

 

It's gotta be in memory or everytime your battery went dead you'd have to do a case relearn. Maybe Les knows more about this.😄

 

Hi George I guess Les never seen the post 😄. I did change the coil but no luck there and some new stuff happening. I'm getting coolant backing up threw my over flow tank. I haven't looked to see if there was bubbles yet but I'm sure it won't be easy to see with the transmission cooler in the rad tank. I did do a chemical test and that came back negative. I have a new rad and water pump. It did it with the old rad and pump as well so I can rule them out as well as the thermostat. I don't see any sign of coolant in the oil. It just backs up out of the over flow. I know that's a sign of a head gaskit but I find it hard to believe. No over heating or white smoke. Any thoughts will be much appreciated😊 thank in advance 🤙

 

Given a new radiator and cap then the most likely cause is a cracked block or blown head gasket. You can test for this with:

1. Chemical test (as you have done)
2. exhaust gas test in radiator
3. pressure test radiator with pump and gauge in the fill neck looking for pulsing or a rise upon snap throttle
4. cylinder compression test
5. look for bubbles in the fill neck

George

 

Case relearn should survive the swap.

 

Hi Les hi George

This truck is a royal pain. Im thinking about getting something else to replace it. I just thought I'd ask your opinion on the the problem first. So i hooked up my scanner and i can see im misfiring on 1 3 and 4. So i changed the wires on one side with brandnew ac delco and still missfires on 1and 3 so i didn't even bother to change the other side 2 4 6 because they are fairly new ac delco wires. It has me stumped. What do you guys think about this. I'd really like to keep driving this truck for the winter but I'm driving with two feet just to keep it going now. Also i only see the missfires at idle. I've replaced the cap and rotor 3 times now with a ac delco and even tried a Chinese one and it's made no difference. I've replaced the coil twice with Delphi. I have a Chinese ignition module now and hope that's not causing an issues. I don't want to pay 140 bucks for a brand name if I'm gonna have to scrap the truck. It was one of you guys that helped me determine with the scantool that I don't have a vacuum leak. I just don't know how I can have 3 cylinders misfiring two of them on one side and one on the otherside ? How's this possible ? I value your opinion and thanks again for all your help. 👍