01 3.4 5 speed will crank no start (long post)

1st time posting, long time stalker but i wanted to share my experience with anyone dealing with the same symptoms. Truck is an 01 3.4 5 speed with 218k miles. After deciding it was getting to risky to drive on my ball joints, parked my truck for about weeks. Have never had 1 problem out of this truck after 12 years of ownership. The day i head out to change my ball joints, boom, truck will crank, no start. Figured the fuel pump took a dump. So i pressed on with the ball joints. Changed plugs since they were due. Still nothing. Changed fuel filter, nothing. Decided to confirm i had spark before diving into the fuel system. Tried starter fluid, no start. Using multimeter, checked efi relay, grounds, coil packs, fuses, just going through the troubleshooting list in a haynes manual. Bought a BT scanner that would never connect, figured it was junk. And hours and hours of research on this forum. Ive been stumped for 2 weeks. Until last night i came across a post with start issues. The guys mentioned something about the CEL not being on with KOEO. Go out to my truck turn the key on, and there it is, no CEL. Finally, a small hint to go off of. Started searching about no CEL, started seeing more posts about bad grounds. So i check mine again, still check good. Then someone mentions corrosion on ecm. I figure no way. So after dead end after dead end. Pulling the ecu is my last ditch effort. Pull it apart, and there it is, corrosion on the ecm board. Just wanted to share and remind the next guy that no matter how unlikley a possible problem is, check it out. And keep hitting that search bar, you'll eventually find someone that has had the same issue at some point. Anyone know if cleaning the corrosion is a possible fix? Or should i start the search for a used ecm.

 

Wow that’s pretty bad, how did water get there? You might have a leaking cowl or bad windshield seal.

 

The only thing i could think of is a few years ago my drain that runs out through the pass side fire wall got clogged. Clogged so bad that when i turned, the water would run out of my lower vents and soak my carpet. Only thing i can think of is when the interior got hot in the summer, it created enough moisture to get just enough in the ecm and just took a while to start causing issues. Everything else under there was dry.

 

How do i post a link to the other guys thread? Just wanna share the post that helped me out.

 

I've tried to fix much less damage on an ECU board. It's the brains, don't take a chance that will leave you stranded, find a new one.

 

I believe thats what im gonna do. Just gotta find a used one. I havent looked but from what i understand, new ones are pretty expensive.

 

What’s the part number on the ECU?

 

I assume it's the 89661-04811 number, but not sure. Or -7760

 

Nice find on the ECU issue. I just looked at https://www.car-part.com/. The going rate from salvage yards in my area for a used one on a 2004 4x4 AT seems to be about $150.

 

Thats not bad at all. Thanks for checking on that. But I believe on another post i saw that for an ECU swap it has to be the same year and options. I haven't researched enough to know yet though.

 

I think you are right... I searched car-part.com for a 2001 4x4 3.4 MT... in my area they seem to come in around $350.

 

You want your numbers to match !!

The harness can be re pinned to work with another ECM but is is time consuming

 

Yeah thats definitely not something i wanna dive into. Any idea if it being trd matters since it has a rear locker?

 

I am doing a manual swap on my truck and ECU is the biggest thing I needed. I learned that as long as it is the same year, engine, 4x4, and M/T that’s all that matters. I was told that the rear diff is not connected to the main ECU.

 

Ok thats what i figured but i wasn't sure. Do you know if it has to be reprogrammed if it comes out of another truck without refurb.

 

From my knowledge it’s plug and play as long it’s the same exact year, model, etc. I haven’t done my swap yet and replaced the ECU so I have no first hand experience just what other have told me that have done it.
You truck may run funny for a day or two while the ECU relearns and adjust to your engine, might just seems under powered or sluggish but should correct itself.

 

Thats what i was hoping. Now to find one. Thanks for the input.

 

As long as the part numbers match !!

It only takes one pin wired different to make things real interesting .

The plugs can be the same the pins won`t be .

Best of luck