2000 Jeep Wrangler – ASD Relay Not Activating – Engine Does Not Start
The shop installed a new relay and was about to install a new PCM.
With the key in RUN position, the ASD relay would buzz and there was no MIL light. The missing MIL light indicated a fault with the PCM as did the buzzing relay.
Checking the relay confirmed power at terminals A13 and A15. Both power feeds were able to hold a load at the power distribution box.
Power to PCM from ASD relay on PCM connector C3 Pin 12 (dg/pk wire) was not present.
Relay control circuit at PCM connector C3 Pin 3 (db/yl wire) was fluctuating between 8 and 4 volts. The PCM was trying to hold the relay coil to ground but could not. If I added a ground, the relay would activate and stop buzzing. The problem was at the PCM as suspected.
Next up was to test PCM power and grounds.
Both Grounds (PCM connector C1 Pins A32, A31 (bk/tn wires)) were good with a value of 0.01 volts, and a value of 0.02 when loaded. These were checked backprobing connector and connector unplugged.
Power at PCM connector C1 Pin A22 (rd/wt) was good when backprobed with a value of battery volts and held when loaded. When I unplugged PCM connector and tested again only 8.13 volts were present. When I loaded the circuit vaoltage disappeared. Since voltage was good on the backside of the connector I knew it would be in the connector itself.
Once I disassembled the connector the problem was found. A corroded pin on the PCM connector. After replacing the pin the vehicle functioned normally.