Hi Guys,
I wanted to share my fried ECU experience with the board. I was backing my truck up to the log splitter to hook it up, kicked on the e-brake and got out to look at alignment. When I was walking back up the truck just shut off like I turned the key off. Turned key off and back on and tried to start. Noticed that fuel pump wasn't kicking on and thought it was that, but giving ground to Pin 4 on the test connector kicked the fuel pumps on and so I started thinking ECU because the fuel pump relay gets its ground from the ECU and all of the wiring that I've traced looks clean and no burns visible. Pulled the ECU and it stinks, so I'm sure something inside cooked. Pulled the ECU apart and confirmed that a capacitor on the board fried. It looks like the capacitor connects to pin 23, which is knock sensor, and testing that pin for short to ground yields nothing, so I think it may have been just internal.

Question for the forum: could this happen spontaneously or do I have some more tracing to do to find a short in the wiring before installing the new ECU?



One of the little legs on the green capacitor in this pic seems to be the culprit.

 

Same place the one on my 91 Bronco failed. I got a new one at NAPA and haven't had any issues since.

 

Awesome, that's exactly what I was looking for. Couldn't find any issues in the harness so I'm just going to slap the new one in there.

 

Update: just installed the new ECU. Truck runs fine now. In fact the idle smoothed out some and there was a hesitation I never figured out and that's gone too. Very happy.