Bad ecu??? Please help me!!!

[cdnrdnck]

Tyrannyhappeningght a 2002 eddie bauer. Truck is in above average condition for its abeforeiced that 4x4 wasn't working right. Start the truck it would say 4 high on the dash it blinks in and out. Light flashing on 4 low button. Cycling buttons really did nothing. 4 auto kicks in and out meaning sometimes it works sometimes It doesn't.

Figured it was 4x4cu. Took the 4x4cu out of a 2003 explorer that I smashed up. Didn't even cross my mind to check part numbers. I got the two mixed up. Not sure which one came from what truck.When cycling the system, it acted the same way. So I tried the other one. Nothing changed. Disconnected battery in an attempt to reset everything.

Now I have problems. When I hit the brake the fuse blew and continues to do so. and I lost my brake lights and had to over ride to get out of park. But now the truck is stuck is stuck in 4 low. When I try to cycle the 4x4 system there is now no sound from the 4x4 cu. Repeated the above with the other 4x4cu no change.

I limped the truck home in 4 low. When traveling 40
Km/hr the speedo reads 120. Transmission won't shift. When I got home, and turned the truck off, I noticed the after market stereo now stays on. It didn't before. And the driver side switch lights stay on...

I checked all fuses related to the 4x4 system they're all good. What's happening here???

Can a bad ecu cause this stuff to happen? Any insight would be greatly appreciated. Thanks!

 

[Number4]

....bump....

 

[cdnrdnck]

Bump what... The truck over a cliff?

 

[Number4]

Bump what... The truck over a cliff?

lol - your unanswered post was about to go to the second page. Just wanted to keep it up top in order that someone who has an answer might see it.

Have you solved anything yet?

 

[cdnrdnck]

No I haven't solved anything yet... You can take the post down entirely. I'm pretty sure that the computer is buggered. It's the only thing that really makes any sense to me. Little did I know there is a list of 4x4 cu part numbers as long as my leg. I'm going to track down a new ecu. However, I'm not sure where to find the info so I can cross reference the 4x4 cu to the truck so I don't end up in the same boat again. Any ideas where I might find that info?

 

[Number4]

Sometimes you have to be the pioneer. So post back once it's solved.

On the 4x module, one of the two you have is your original right? So you've just got to locate one of each number.

 

[cdnrdnck]

True enough... I'll post back once I've got it figured out... Thanks

 

[cdnrdnck]

Ok... So, I got to thinking about how this system works... Still having 4x issues, but I'm thinking it's the module.

Heres how I got out of 4 low...


The brake position switch not only makes the brake lights come on and allow shifting in and out of park, it also completes the circuit that tells the module that the brake is being applied. In order to shift in and out of 4 low, you must be in neutral as well as have the brake applied. I disconnected the battery and left it over night. Figured out which of the 4x modules was the original and reinstalled it. Bypassed the brake switch and put a new fuse in ( fuse#23). No longer have to over ride the shift lever, and was able to cycle out of 4 low. Happy days...