Apologies if this is not the correct forum but here goes:

So I opened up the case on an auto P28 I recently bought only to find the D5 Diode had popped out and was still loose in the case (see pics below). In searching I've found this is a protection for reversing the battery cables and basically protects the ecu circuitry.

1) Is there any way to determine if the diode is still good?
2) Does anyone have a part number from like digikey or something that I could use for a replacement or know what to search for? I've read this is a 5-amp rectifier diode, is that correct?
3) Other than hooking the ECU up into a running car, is there any other way to tell if its still working? None of the traces or other components appear fried.

Thanks!

 

sounds like your the guy i need to talk to. but first i believe to check a diode you take your ohm meter and check the resistance of the diode. one way you will get continuity and if you swap your test leads you should get no continuity. if that makes any sense. my question to you is. i have a 1994 accord, and the egr is on at idle, making the car run rough and stall. the power for the egr solenoid is provided through ignition switch and then the ecm provides the ground to the solenoid when needed. could i possibly have a bad diode in the ecm letting it be grounded all the time? i have replaced the ecm and checked the wires from ecm to solenoid for shorts to ground and found nothing . just thought you might have some input on this