Check Engine Light

[mhuppertz]

New alternator, brand new yellow top battery, two different PCM's, three different ignition switches, same issue. Bouncing volt meter that sets a CEL, diag code says "low voltage condition detected".
Grounds look good, must be low voltage supply to the PCM but I can't find it!
Driving me nuts.
Ideas?

[DodgeFreak]

have you put an actual volt meter on the battery to make sure it was charging?

[mhuppertz]

I haven't but I drive it at night and it hasn't killed the battery, although the brightness waivers along with the needle.

[mhuppertz]

I tried bypassing the PCM (with a brand new external regulator) and it did the same thing, although I did not try using a relay to bring power straight from the battery.
To me this suggests a power supply issue TO the PCM but I just can't find it.

[PToombs]

Are you checking the power to the PCM with it plugged in or unplugged? You need to check it plugged in. If you check it unplugged you will get 12 volts, but there is no load. Plugged in the PCM is drawing power and a low voltage will show right up.