What does it mean?
P1389 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: No Auto Shutdown Relay Output Voltage To PCM .
Symptoms
- Engine cranks but will not start, or starts and stalls immediately
- MIL on with several related injector and coil circuit codes stored
- Intermittent stalling while driving, restarting after a short wait
- No fuel pump prime or injector operation when the key is turned on
- Repeated fuse failure in the same circuit
Likely causes
- Failed auto shutdown relay contacts
- Blown fuse in the circuit fed by the relay
- Corroded, burnt or spread terminals in the relay socket
- Open circuit in the relay output wire running to the PCM sense input
- Short to ground on the relay output circuit repeatedly blowing the fuse
- Poor PCM ground or a failed relay control driver inside the PCM
- Water damage or corrosion inside the underhood fuse and relay box
How to fix it
- Check the relay fuse and swap the relay with an identical one to see if the fault clears
- Measure voltage at the relay output terminal with the key on and again while cranking
- Inspect the relay socket for melted, discoloured or spread terminals and corrosion
- Trace the output wire to the PCM, checking continuity and testing for a short to ground
- Verify the control side: the PCM should ground the relay coil during cranking
- Perform voltage drop tests on the PCM power and ground circuits
- Repair the wiring or replace the relay, and suspect the PCM only once every circuit tests good