Bobcat698
Pure Diesel Power
- Joined
- Apr 24, 2006
- Messages
- 2,229
Working on a customers 94 Dodge 2500. We have two days into trying different things to get this issue fixed to no avail.
Old engine, everything worked fine. We pulled it (melted) and installed another engine.
New engine will start just fine, the shutdown solenoid pulls up and stays up while running. All the dash gauges work EXCEPT the tach, and we have no charge (obviously because it sees no engine speed reading).
Upon further testing the PCM is not giving a 5V signal/reference to the CPS.
While checking grounds, we noticed that with the key on ONE of the two grounds (the ground for the shutdown solenoid) has 12V. If you unplug the shutdown solenoid but leave the key on, the 12V goes away and has continuity to ground. Same if the key is off.
We plugged in a brand new shutdown solenoid and the same exact thing happened, so I'm ruling that out.
At some point we blew the #9 fuse, which caused the shutdown solenoid to pull up upon cranking, but it did not stay up once running. We replaced it and never had another problem.
All 3 wires to the engine speed sensor ohm out just fine, no short that we can detect.
Does anyone have any ideas? Alldata doesn't show the correct pin-out for the PCM so we are having a hard time trying to see if there is power where there is supposed to be power.. We are thinking maybe the PCM isn't getting power on a certain circuit, so it is not putting 5V out.
Thanks in advance!
Old engine, everything worked fine. We pulled it (melted) and installed another engine.
New engine will start just fine, the shutdown solenoid pulls up and stays up while running. All the dash gauges work EXCEPT the tach, and we have no charge (obviously because it sees no engine speed reading).
Upon further testing the PCM is not giving a 5V signal/reference to the CPS.
While checking grounds, we noticed that with the key on ONE of the two grounds (the ground for the shutdown solenoid) has 12V. If you unplug the shutdown solenoid but leave the key on, the 12V goes away and has continuity to ground. Same if the key is off.
We plugged in a brand new shutdown solenoid and the same exact thing happened, so I'm ruling that out.
At some point we blew the #9 fuse, which caused the shutdown solenoid to pull up upon cranking, but it did not stay up once running. We replaced it and never had another problem.
All 3 wires to the engine speed sensor ohm out just fine, no short that we can detect.
Does anyone have any ideas? Alldata doesn't show the correct pin-out for the PCM so we are having a hard time trying to see if there is power where there is supposed to be power.. We are thinking maybe the PCM isn't getting power on a certain circuit, so it is not putting 5V out.
Thanks in advance!