I want to test my ECM’s relay. My 94 22RE suddenly quit after years of reliability. It’s got fuel and the plugs are getting spark, so I’ve been checking relays and fuses. Now I’m on the relay that’s near the driver side kick panel, I’m not positive it’s for the ECM but did read that there was one there. I see a harness plugged into 4 terminals on the big plastic cover above what looks like a control unit. The 4 wires are obviously on a relay behind the cover., one is always hot. It’s about 8 gauge so must be 12V. So question is, should I Hotwire those terminals to bypass the relay and see if that fixes the problem ( allows engine to start) or could it damage the computer? I would hate to destroy a good ECM. I replaced the fuel filter, EFI relay, and did a lot of testing. The O2 sensor wires look good.

 

ECM failure is very rare. You can open the lid and look/smell the circuit board. About the only way to hurt it besides driving into a creek is to backfeed power through the unit. that could end badly.
Circuit boards that have shorted smell bad. you can't miss the smell.

 

Thanks, I ordered a service manual so I don’t do that. My ECU is behind the right side kick panel, and the glovebox, it looks and smells not too bad. I checked the two relays above it. The relay I was talking about is behind the left kick panel but it’s well hidden except for it’s pins that stick throo and go to a 4 wire harness. I think I’ll test them since they’re far from the ECU. Meanwhile there’s not much to do. I’m checking the AIC and the AFC today but there was no misfiring or anything warning me of an impending shutdown so when I get the manual I’ll locate all the relays and grounds and check them out. If I can’t find the problem I’ll put a carb on it because it only has 80,000 on a total rebuild and doesn’t use a drop of oil.