alyvenegas

hi, i have a chevy venture van and its reading a code that we cannot figure out what it is it says "P1639" all tha computer says is:

Definition: PCM 5 volt reference voltage circuit condition.
explanation: The ECM has detected a fault in the 5 volt reference voltage line.
Probable Cause: 1.- Sensor using 5 volt reference line shorted to ground
2.- circuit short to ground.

Can somebody help me figure what it is so we can fix it please...... thank you

shawnvw

check for a grounded wire somewhre between your engine sensors, and the PCM. Most of the sensors use a 3 wire setup: ground, 5v positive, and signal back to the computer.

alyvenegas

hi whats PCM stand for,,,, sorry... hahaha but i dont know much about mechanic terms...... thanxs....

Captv2k

do you have a diagram to where these sinsors are located so I can trouble shoot this problem. I also have a code of P1639 now i have to disconnect my battery cause my head and rear lights would stay on with the key off. At one time one of the relay was over heating and blow up a few fuses where the a few things wherent working now the radio don't work before it stop working we smilled somthing burning can it be a wired burned inside the radio, the radio does turn on but the speakers won't work. You can hear a sound coming out of the speakers when you turn the ignition on and when you try to push on of the power window buttons wish in fact don't work. I had to take off the positive battery in order to shot off the lights. If the radio had a short woudn't the radio not turn on. I have a big project now and this the only car my wife has to get around. I pray it doesn't get cold so I can fix this problem any advice would be apprecaited. Thank You.