mdd0127
03-27-2006, 09:19 PM
The intake heaters on the 95 cummins aren't cycling. I've tested the relays, heater grids, and intake air temperature sensor and they're all fine. The pcm is only sending 4 volts down the blk/rd wire to the IAT sensor. When it sees the load of the sensor, it drops to 2.5 volts. If I run an ignition 12v feed to the sensor, the heater grids start working perfectly but the wait to start light flashes. If I can determine what the voltage input should be, I can diode isolate a new feed at the correct voltage and hook the old wire back up to the pcm so it "sees" the load of the sensor. This would save me a bunch of money. I don't want to buy a new pcm. I have checked and rechecked all grounds/connections and wiring so it has to be the pcm. If someone could test the voltage of the blk/rd wire going into the IAT while the truck is running, I'd really appreciate it. Thanks