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Quote:

Originally Posted by carfixer007 (Post 1645605)

I may have inferred something. @atentaten You did or did not check that the PCM was grounding the relay? If not then we need to make sure it see's everything needed to ground the relay. I assumed the PCM was grounding but it was getting lost between the pcm and relay. My statement about running a redundant ground was that you would do new from the PCM and feed it the easiest way to the relay and tie it in. The problem I've seen with some is the wiring will get bad at a junction or at the bulkhead connector if it goes through there. Rather than taking it all apart and trying to find the culprit is to leave it as is a run the new redundant wire.
Clear as mud?

My check that the PCM was grounding the relay was made by observing voltage between the YEL 76(PCM ground) and the hot side of the relay coil on start/run. Volts were being read, the circuit was not open, so the PCM must've been doing the grounding part. The quality of the ground in terms of it delivering enough current to handle the load seems to be in question. I got it re. redundant ground: run a new wire without removing the old one.

Quote:

Originally Posted by atentaten (Post 1645608)

My check that the PCM was grounding the relay was made by observing voltage between the YEL 76(PCM ground) and the hot side of the relay coil on start/run. Volts were being read, the circuit was not open, so the PCM must've been doing the grounding part. The quality of the ground in terms of it delivering enough current to handle the load seems to be in question. I got it re. redundant ground: run a new wire without removing the old one.

Maybe better to say it will not allow enough current due to added resistance in the circuit. Do the redundant wire unless you are wanting to find the actual problem with the wire that is there.

Quote:

Originally Posted by carfixer007 (Post 1645609)

Maybe better to say it will not allow enough current due to added resistance in the circuit. Do the redundant wire unless you are wanting to find the actual problem with the wire that is there.

One thing that I did do to check the PCM ground wire (YEL 75) was to use it in a loaded circuit to see if it could light a test lamp. This involved taking the harness off the PCM and directly connecting a body ground to the wire and using a test lamp to connect to a B+ source and where YEL 75 comes up into the start 1 relay socket in the fusebox. The lamp lit up, so enough current flowed through the wire, whereas when trying to do a load test with the PCM doing the grounding, the lamp would not light even though voltage was there. So that lead me to believe that the wire itself was fine and there was either some problem within the PCM's grounding circuitry or some wire providing the PCM with ground. At some point after this, the issue with the crank voltage on PCM 23 being 0.5 volts instead of the 12V that it was previously came up.