2014 Jeep Wrangler JK Factory Service Manual 28 - DTC-Based Diagnostics

P0688-AUTO SHUTDOWN RELAY SENSE CIRCUIT LOW

For a complete wiring diagram, refer to the Wiring Information.


Theory of Operation

For specific relay location and type, (Refer to 04 - Vehicle Quick Reference/Fuse Locations and Types - Specifications) .


POSSIBLE CAUSES

(A14) FUSED B+ CIRCUITS
(K51) ASD RELAY CONTROL CIRCUIT OPEN
(K51) ASD RELAY CONTROL CIRCUIT SHORTED TO GROUND
ASD RELAY
POWERTRAIN CONTROL MODULE (PCM)

Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).


1. VERIFY ASD DTC



NOTE: If any O2 SENSOR HEATER CIRCUIT HIGH DTCs set along with P0688-AUTO SHUTDOWN RELAY SENSE CIRCUIT LOW, all of the O2 Sensor Heater Control circuits need to be checked for a short to battery voltage.

NOTE: If any of the following component DTCs have set along with P0688, diagnose them first before continuing.

  • Ignition Coil(s)
  • Fuel Injector(s)
  • ASD Control
  • ASD Control Output (TIPM DTC)
1. With the scan tool, erase the DTC.
2. Attempt to start the engine. If the engine will not start, crank the engine for at least 15 seconds. It may be necessary to repeat several times.


Does the DTC return?

Yes


No


2. ASD RELAY

1. Turn the ignition off.
2. Install a substitute relay in place of the ASD Relay.
3. Ignition on, engine not running.
4. With the scan tool, erase DTCs.
5. Attempt to start the engine.
6. With the scan tool, select View DTCs.


Does the DTC return?

Yes


No


3. CHECK THE (K51) ASD RELAY CONTROL CIRCUIT OPEN
1. Turn the ignition off.
2. Remove the ASD Relay.
3. Disconnect the C1 PCM harness connector.
4. Measure the resistance of the (K51) ASD Relay Control circuit from the Relay connection to the PCM C1 harness connector.


Is the resistance below 5.0 Ohms?

Yes


No


4. CHECK THE TIPM INTERNAL (K51) ASD RELAY CONTROL CIRCUIT FOR AN OPEN

1. Turn the ignition off.
2. Remove the ASD Relay.
3. Disconnect the TIPM C2 harness connector.
4. Measure the resistance of the (K51) ASD Relay Control circuit from the Relay connection to the TIPM C2 harness connector.


Is the resistance below 5.0 Ohms?

Yes


No


5. CHECK THE (K51) ASD RELAY CONTROL CIRCUIT FOR A SHORT TO GROUND
1. Measure the resistance an the (K51) ASD Relay Control circuit at terminal 85 of the PCM C1 harness connector.


Is the resistance above 10k Ohms?

Yes


No


6. (A14) FUSED B+ CIRCUITS
1. Turn the ignition off.
2. Using a 12-Volt test light connected to ground, probe the (A14) Fused B+ circuits at the Relay connection.


NOTE: The test light should be illuminated and bright. Compare the brightness to that of a direct connection to the battery.


Does the test light illuminate brightly?

Yes


No


7. POWERTRAIN CONTROL MODULE (PCM)

1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the ASD Relay and the Powertrain Control Module (PCM).
2. Look for any chafed, pierced, pinched or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals. Verify that there is good pin to terminal contact in the ASD Relay and Powertrain Control Module connectors.
4. Perform any Technical Service Bulletins that may apply.


Were there any problems found?

Yes


No