Tntech if I have no cel and the bulb is good will a scanner be able to communicate with pcm. When key on allother lights come on briefly except cel

 

Update guys. No com with cpu and all sensors that should get 5v are only gettin bout 2.4. Makes me think new cpu but this is number 3 now???

 

At that point I'd be grabbing the factory service manual (for reference) and disconnecting sensors one at a time to see if one of them is fubar, also moving wires this way and that to determine if there's a short to ground somewhere pulling that voltage down. Could be the PCM is at fault, but it would suck to replace the thing only to find that the symptom doesn't change because some sensor is failed.

 

I found your thread and there's your answer bro ^^^(above) and just cause no scan comm with PCM doesn't mean bad PCM

 

Ill check some more but crank sensor pickup coil coil and cpu are all new. What other sensors would affect it like this. As for wiring I've been checkin like crazy. I heard somethin bout cpu voltage flowing through brake switch and that if the switch is bad it can shut down spark and fuel. Any one heard of this?

 

Coolant temp sensor, MAP sensor, Throttle position sensor, Battery temp sensor, Crank sensor, Distributor pickup. The O2 sensors can take the PCM offline too. Just go around unplugging things. Reboot the scan tool and check the communication after every one.

 

call me crazy but shouldn't the neg bat cable be off when working on sensors?

 

Yea, but sometime's when troubleshooting you can't.

 

what about the nuetral safety switch since he did a tranny ? would that make a difference?

 

No time today will check more tomorrow. Just unplug a sensor and see if scanner says anything different? I appreciate all the help guys. Hopefully it'll be goin soon and well know what the issue is. Anyone have any input on the brake switch question asked in last post?