roger.svoboda Posted May 27, 2009 Share Posted May 27, 2009 Anyone know or have the circuit diagram for the ecu boards in a 85 z31. I've got two ecu's one starts but won't run and the other starts runs for about 5 minutes then goes to barely running. Took the covers off and found three diodes (D90, D64, and D19) that are side by side close to the input plugs. They appear to be either input or output as they go to the smaller plug. One unit has D90 blown and the other has D19 blown along with some burnt board conductors. I can repair them both with some new diodes and creative wiring but it would be nice to know what caused them to fry or at least what they are connected to outside the ecu. thanks to any who can shed some light on this. Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted May 28, 2009 Share Posted May 28, 2009 Backwards jump start is usually the culprit but I've seen that damage occur from a person who thought disconnecting the battery terminals while the car was running is a good way to test the alternator. A lifted body to engine ground can also cause crazy spikes and transients. Quote Link to comment Share on other sites More sharing options...
roger.svoboda Posted May 29, 2009 Author Share Posted May 29, 2009 nope wasn't that. we disconnected the battery. removed computer put it on shelf. swapped the engine and stuff. reinstalled battery. started right up and drove it to where it was going. started the funny running soon after that. installed the computer from donor car and everything was good. Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted June 3, 2009 Share Posted June 3, 2009 Battery tipping over and touching positive terminal to the body or an a/c line will also do that. I repaired about 10 ecus a day for standard motor products and there were a lot of tipped batteries that burnt the zener diodes. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.