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My 1997 PCM is not sending the voltage signal to the alternator on the Clear (C2)-35 (BRN) wire so the alternator is not charging. I'm searching for possible solutions as I have exhausted my ideas.
The car is a 49 austin with a near stock 1996 3.8L engine/auto transmission installed using the stock engine wiring harness. The PCM is a 1997 (same pinouts as 1996) to allow tuning, but I had the same problem with the 1996 PCM. The dash is from Dakota Digital. I have wired the OBDII plug. Power loads are similar to a stock firebird.
I have checked all the usual suspects. The electrical continuity on the brown control wire from the alternator to the PCM is good. Ref voltage at the PCM is 5v (ign on). Grounds at the PCM check out as do the batt voltage at the PCM Blue-20 (12.15v). Dash volt indicator shows 11.8v. Engine runs well and I have no other electrical problems. The voltage on C2-35 at the PCM with ignition on is 0. The alternator is new and it checked out (14.5 v output) at an autoelectric shop. Car starts easily with good starter power supply.
Some questions:
- Do I need to have the red PCM alternator indicator wire (C2-16) connected to the instrument panel, as I have a aftermarket dash and I have it open circuit? I have the stock panel so I could test this.
- Does anyone have info on the control logic or inputs the PCM monitors for alternator control?
- Any other ideas on what could be the problem?
Any help with this problem would be fantastic! Thanks.
The car is a 49 austin with a near stock 1996 3.8L engine/auto transmission installed using the stock engine wiring harness. The PCM is a 1997 (same pinouts as 1996) to allow tuning, but I had the same problem with the 1996 PCM. The dash is from Dakota Digital. I have wired the OBDII plug. Power loads are similar to a stock firebird.
I have checked all the usual suspects. The electrical continuity on the brown control wire from the alternator to the PCM is good. Ref voltage at the PCM is 5v (ign on). Grounds at the PCM check out as do the batt voltage at the PCM Blue-20 (12.15v). Dash volt indicator shows 11.8v. Engine runs well and I have no other electrical problems. The voltage on C2-35 at the PCM with ignition on is 0. The alternator is new and it checked out (14.5 v output) at an autoelectric shop. Car starts easily with good starter power supply.
Some questions:
- Do I need to have the red PCM alternator indicator wire (C2-16) connected to the instrument panel, as I have a aftermarket dash and I have it open circuit? I have the stock panel so I could test this.
- Does anyone have info on the control logic or inputs the PCM monitors for alternator control?
- Any other ideas on what could be the problem?
Any help with this problem would be fantastic! Thanks.
