2nd Gen Non-Engine/Transmission PCM not firing the Alternator

[dwstover]

HI Guys: Several days ago, my "check guages" light came on and the Alternator was showing no charge. Checked 140 amp fuse-OK. Had local garage check Alternator output checked- 0 volts. batteries (two optima's) reading just under 12 volts. Troubleshooting indicated no PCM triger. Checked wires for execive voltage drop- no problem. Ordered new PCM and had the truck towed (nearly 100 miles-I'm stuck in Homer Alaska) for instalation and programing. 4 hours later, same problem, no output from PCM. We hot wired the Alternator to verify that it would charge if it were trigered and it did. So we ordered another PCM. I am assuming that the Chrisler techs checked the battery heat sensor and the Engine speed sensor since thy had the DRB connected for some time and I heard the truck engine being spun up. All grounds and connections were checked and cleaned. I don't know if they did anything to the engine speed connector. Everything seems to point to the PCM. I just find it hard to believe that two PCM boards have the same failure. Have I missed anything I should be checking or suggested? BY the way, the first PCM cost me $ 400. 00+. The second on is costing me $1500+. I think there is a letter to DC in the future assuming I can ever get back home to New Mexico.

 

[bmoeller]

Sounds almost like the PCM may not be getting an RPM reading.

 

[DSiemens]

The PCM needs a signal from the crank sensor to turn on. Good chance the crank sensor is bad or the electrical connection needs cleaning. Been there and done that.



Dan

 

[dwstover]

PCM still not working

Thanks for your help guys. But the second PCM is showing the same problem.

Crank sensor has been checked, I think the speed sensor is the same thing.

Any ideas of where to look now.