So here's the scoop. I'm new to this forum thing. Funny because I do IT for a living. Anyways I have a 1989 Jeep Cherokee, no engine or electronic mods as far as I now. I have a diode (Seems to be heavy duty) that keeps burning up. I can't find out what circuit it runs. I know this seems pretty vague, but ask me any questions for information and I'll tell you. Any help is greatly appreciated.
PLEASE HELP ME!!!!!!!

 

Are you able to take digital photos and post them up to see what you are talking about.


Sounds like a ballast resistor.

 

The problem area is circled in red. It's diode "C826". I can't find a diagram for what it runs. Nor can I trace it to the pin. Or maybe I can and I don't know what I'm looking for. Does this help at all?

 

I have no idea what that's for. The closest I can get to the functions of the ECU is this diagram of the ECU external components. If you could trace what connector pin number that diode is connected to you could try and rectify the issue.


What issues are you having with the Jeep? Not running correctly, not starting, etc.?


Poor pic of the diagram. Depress and hold the Ctrl key while tapping the + key to make the image larger.

 

What pin numbers does that diode coincide with.

What issue are you having?

 

Good one Bob. I've heard of the Renix ECU considered "aircraft grade". Guess there are "power transistors" for the injectors that might fail, (6, one each).

Bonehead here is just ringing in, you already have about the best help imaginable here. (wonder what that other toasted looking brown transistor? does)

A wise man once said " If you're going to the JY, get one out of a 1989 or 1990 with the part number ending in 428."

 

What is that that makes you think it"s "heavy duty" ? You say "keeps burning up". Is it open? What readings do you get testing the burnt up heavy duty diode? Open? or open , one way or the other, closed? More could help us greenhorns! I do happen to know how they normally fail.

 

So what isn't working? If it's a protection diode (meant to protect an output device like a transistor from reverse current), you may have to lift the diode to open the circuit and see what stops working.
My money is on the A/C clutch relay driver. Just a hunch.