HELP! - Transmission / PCM ???

[ddubb]

ALright, this is the second time I am posting on this forum. Nobody answered my first one about 8 months ago.

I have a 94 Camaro with the 4L60E transmission. So Ive been replacing alot of parts on the vehicle, and when I checked out the transmission, the Wiring harness was fried. Apparently, it came disconnected, and touched the exhaust pipe and the main power wire shorted out completely.

So Ive replaced all of the burnt wires in the harness, and now I'm getting very low voltage ( like .06 volts - LOW, but not completely dead ) from the power wire that should supply power to the transmission internals.

Is it possible that this is a bad PCM now causing this problem ??? This car has been nothing but trouble. It seems that as soon as I fix one thing, something else has a problem. I dont want to put in a new PCM if its not going to fix anything. The vehicle runs fine, but im not getting any power to the transmission. Is it possible for me to run a power wire directly to it instead and hope that the PCM will still activate the shift solenoids, etc ??

Please help!!!


- Dan

[ddubb]

Update : Ive been searching online for hours, and Ive come across a few wiring diagrams for the transmission.

Apparently the power wire to the transmission goes to the Under hood fuse #11. This wire goes to the transmission and splices to the interior fuse box somewhere ?? It is labeled Ignition. I can start up my car no problem, but this electrical is giving me trouble with the tranny.

Does anybdoy have any wiring diagrams of the engine underhood fuse box and the interior fuse box, etc ???

Thanks

- Dan

[fastTa]

How did you splice together the wires? You cannot use butt connectors because they will act effectively as a inline resistor. Sometimes even correctly soldered splices will not carry the proper voltage.

[ddubb]

I think I have it figured out for the most part. I replaced all 14 wires in the transmission wiring harness. They were all completely burnt and fried from touching the exhaust.

I soldered the connections together very well. For the most part, they shouldnt be a problem as the main shift solenoids are always hot and the PCM grounds them out, so resistance isnt an issue there - possibly the transmission operating temperature sensor, but the most resistance I have been getting is .1 ohms across the length of the wire from the pcm to the transmission connector.

I have got the main power supply to it .. somebody had placed a 30 amp fuse in the #11 underhood ignition slot which was bad, so I replaced it with the normal 10 amp fuse and it has 12 volts at the transmission connector now when the Ignition is in the Run and ON position.

I have removed the transmission, there was a pretty big leak at the front main seal, and ALOT of metal inside of the transmission pan. I dont know if the leak was caused by the transmission. Apparently, when there is no power to transmission it will run at maximum pressure ??? Im not taking any chances with a blown transmission, so I already have a replacement transmission ready to be installed and a brand new radiator which is already in place. In the process, I snapped one exhaust manifold bolt on each side when removing the exhaust !!!

All I can say is that these cars are a PAIN to work on, no room to get to anything under the car. Hopefully this weekend I will have everything re-installed and the car working again. Crossing fingers at this point.

- Dan

[fastTa]

The PCM monitors all of the transmission sensors and indicators very closely and it expects a certain voltage window at various pre-set trans temp tables. If this voltage is outside of this expected range, the 4L60E can be placed into 'Limp Mode' to protect the trans from any further damage. The PCM instantly commands a very high line pressure ignoring the normal continuously varying line pressure commands, turn off the shift solenoids, and defaults to a single gear; usually 2nd or 3rd. The reason for this is to protect the bands and clutches should there be a 'real' problem. This could also be a reason why you were getting very low voltage readings to the shift solenoids and other various sensors.