Did I lose my ECM? 03 Yukon dead in the water

[Elmerwood]

Yep, that's about what I meant when referencing the splice comb

Just watched a few youtube videos all about this which makes me hopeful I can find the issue tonight.

 

[Elmerwood]

Well I tried what @TJ Baker was recommending and pulled the data bus splice comb and checked voltages on the pins inside and found 11+ volts on pin M & B. According to the drawings in the link I shared above M&B are the ECM and BCM. I pulled the ECM cover off and then the removed the electrical plug to find it gummed up on one side with tacky and wet substance. The friend I picked this up from rinsed the engine bay a couple months ago and I bet this was collateral damage. I'm really hoping this is it. I removed the blue cover and you can see the pins are discolored from sitting in this solution for some time. I think I'm going to try to clean it with some electrical cleaner, a brush and some air.

 

[Elmerwood]

Its alive! That connector was the issue. I cleaned it with electrical cleaner, electric tooth brush and air. Slapped it all back together and everything is back to normal. Going to leave my truck at my shop tonight and take her home for the evening. Thank you to everyone that pointed me in the direction of this fix that was huge. I just purchased this from my friend for 4k and it didnt make it 24 hours after the sale until it died. He would have taken back if I didn't want to deal with it but looks like I may keep it now. Some of the pins had started to lose some plating from the moisture. Do you think it would be hard to find a new wire harness for this? I could just install new female pins as I have the proper crimping tool for those ends I just need the little tool to push them out the back of the connector. I just think a new or used harness would be easier.

Thanks again

 

[Doubeleive]

unless it is some form of pigtail that you pluck out of the junkyard then I don't know, gm only sells the plastic connectors as far as I was told I was trying to get a couple for my fuse box and the dealer parts guy said they only sell the plastic portion that you have to re-pin.

 

[Fless]

Well I tried what @TJ Baker was recommending and pulled the data bus splice comb and checked voltages on the pins inside and found 11+ volts on pin M & B. According to the drawings in the link I shared above M&B are the ECM and BCM. I pulled the ECM cover off and then the removed the electrical plug to find it gummed up on one side with tacky and wet substance. The friend I picked this up from rinsed the engine bay a couple months ago and I bet this was collateral damage. I'm really hoping this is it. I removed the blue cover and you can see the pins are discolored from sitting in this solution for some time. I think I'm going to try to clean it with some electrical cleaner, a brush and some air.

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Sweet! Be sure to verify the integrity of both gaskets that are hopefully stuck to the PCM.

 

[exp500]

Pins are available, first have to figure out what they are.Usually about $0.45-$1.00ea in bulk. Many sources.

 

[Rocket Man]

Awesome news. If it were me, I clean it all up and use some dielectric and monitor it.

 

[Handy Man]

Welcome to the forum from Oregon. You did not say where you are at but with you going to a cabin, I am going to assume, I hate doing that by the way, that you live where snow is and likely have salt on the roads. The first things I would have checked is part of what you have already done but I would do these checks for ground problems that these NBS rigs are known for. here is a link: https://www.fixmyoldride.com/Chevro...e7e5cd24ed24635&at_ab=per-2&at_pos=3&at_tot=4

very well written response. Also, right on the money. Had the same (only much weirder random electrical problems) and finally found faulty batterty cables that appeared brand new on the outside. been working great til now. (see my post

 

[rockola1971]

Well I tried what @TJ Baker was recommending and pulled the data bus splice comb and checked voltages on the pins inside and found 11+ volts on pin M & B. According to the drawings in the link I shared above M&B are the ECM and BCM. I pulled the ECM cover off and then the removed the electrical plug to find it gummed up on one side with tacky and wet substance. The friend I picked this up from rinsed the engine bay a couple months ago and I bet this was collateral damage. I'm really hoping this is it. I removed the blue cover and you can see the pins are discolored from sitting in this solution for some time. I think I'm going to try to clean it with some electrical cleaner, a brush and some air.

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Holy Cow! That thing has aliens growing on the connectors. This is why "you" dont power wash the engine compartment! The seals on these connectors are not made for 80PSI+ of streaming water and soap.