Just bought an 87 Comanche the wiring is a thing of beauty! (Not!) She’s a non runner. anyway I’m tracking down my issues one by one and at this point I get a crank but no start and no spark. the smaller yellow wire to the icu is only getting .64 volts (supôs-se to be 5v) also the TPS is only getting .2 volts I’m thinking I have a short to ground on one of the 5v reference wires. If I put my meter to ohms and connect to the 5v wire and touch to ground I get continuity but unplugging either plug ab or cd from the Ecu I lose continuity... is there a list of which sensors use 5v? I haven’t been able to check the cps according to cruiser54s test but it looks like the Po put a brand new on. I get power and grounds to the Ecu except for the latch relay but if I jump 12v to the ecu from the relay socket I have no change in readings.. any help would be appreciated

Thanks Garrett! I unplugged the TPS, MAP, and the ICU with no change is there anything else that takes 5v?

The Renix only has 2 wires for the crank so I don’t think it gets 5v ref. I took my better multimeter home last night and checked the CPS voltage and it was low (around .25v) this morning I went out and unplugged the dizzy thinking maybe it had 5v to it and magically my 5v came back to my tps so i checked the icu and had 5v there... so I plugged the dizzy back in to see if it would drop again and it didn’t 🤷*♂️. So I decided to pull the top bolt from the cps and get it closer to the flexplate for temporary testing I now get .45 which I hear is good and checked it all the way at the ECU and I still get .45 so it should spark right? well it’s still not sparking anyone know any other good tests to isolate the problem?

I think I found a problem! Cracked open the computer and found these

Well I opened the ECU and found part of the sensor ground burnt up I soldered it back but no improvement was shown also the computer was commanding the fuel pump on whenever keyed on so I ordered an 89 ECU should get it in the morning... gonna need a fuel pump for sure and the tank needs cleaned out... hasn’t been driven since 2011 I think. Thanks for your help Cruiser, I plan on performing many of your tips, I am only waiting to get it functioning to some point so I can tell when I do something right and when I’ve screwed something up

Got it! new Ecu and fuel pump along with many other misc items and it’s running! Thanks for the help! I will be performing the tips soon! But it needs a lot more work before driving daily