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

P0683-GLOW PLUG MODULE SIGNAL CIRCUIT MALFUNCTION

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


Theory of Operation

The Glow Plug Module has the appearance of a large relay and is located next to the battery. The Glow Plug Module receives a signal from the Powertrain Control Module (PCM) to activate the Glow Plugs. The Glow Plug Module supplies power to the Glow Plugs and a ground path is provided through the body of the Glow Plugs. The Glow Plug Module communicates with the PCM over the (K330) Glow Plug Module Control circuit.



Possible Causes

(K202) GLOW PLUG MODULE CONTROL CIRCUIT SHORTED TO VOLTAGE
(D330) GLOW PLUG MODULE SIGNAL CIRCUIT SHORTED TO VOLTAGE
(K202) GLOW PLUG MODULE CONTROL CIRCUIT SHORTED TO GROUND
(D330) GLOW PLUG MODULE SIGNAL CIRCUIT SHORTED TO GROUND
(K202) GLOW PLUG MODULE CONTROL CIRCUIT OPEN/HIGH RESISTANCE
(D330) GLOW PLUG MODULE SIGNAL CIRCUIT OPEN/HIGH RESISTANCE
GLOW PLUG MODULE
POWERTRAIN CONTROL MODULE

1. CHECK FOR ACTIVE DTC



NOTE: If the PCM detects and stores a DTC, the PCM also stores the engine/vehicle operating conditions under which the DTC was set. Some of these conditions are displayed on the scan tool at the same time the DTC is displayed.

NOTE: Before erasing stored DTCs, record these conditions. Attempting to duplicate these conditions may assist when checking for an active DTC.
1. Turn the ignition on.
2. With the scan tool, erase PCM DTCs.
3. Perform several engine run cycles, turning the ignition off for at least 20 seconds between each engine run cycle.
4. Turn the ignition on and wait at least 90 seconds.
5. With the scan tool, read PCM DTCs.


Did this DTC return?

Yes


No


2. CHECK THE (D330) GLOW PLUG MODULE SIGNAL AND (K202) GLOW PLUG MODULE CONTROL CIRCUITS FOR AN OPEN/HIGH RESISTANCE

1. Turn the ignition off.
2. Disconnect the Glow Plug Module harness connector.
3. Disconnect the PCM C2 harness connector.
4. Measure the resistance of the (D330) Glow Plug Module Signal circuit between the Glow Plug Module harness and the PCM C2 harness connector.
5. Measure the resistance of the (K202) Glow Plug Module Control circuit between the Glow Plug Module harness and the PCM C2 harness connector.


Is the resistance below 5.0 Ohms for both measurements?

Yes


No


3. CHECK THE (D330) GLOW PLUG MODULE SIGNAL AND (K202) GLOW PLUG MODULE CONTROL CIRCUITS FOR A SHORT TO GROUND
1. Measure the resistance between ground and the (D330) Glow Plug Module Signal circuit at the Glow Plug Module harness connector.
2. Measure the resistance between ground and the (K202) Glow Plug Module Control circuit at the Glow Plug Module harness connector.


Is the resistance above 10k Ohms for both measurements?

Yes


No


4. CHECK THE (D330) GLOW PLUG MODULE SIGNAL AND (K202) GLOW PLUG MODULE CONTROL CIRCUITS FOR A SHORT TO VOLTAGE
1. Remove the ASD Relay from the TIPM.
2. Connect a jumper wire between cavity 30 and cavity 87 of the ASD Relay connector.
3. Turn the ignition on.
4. Measure the voltage of the (D330) Glow Plug Module Signal circuit at the Glow Plug Module harness connector.
5. Measure the voltage of the (K202) Glow Plug Module Control circuit at the Glow Plug Module harness connector.


Is the voltage below 1.0 Volt for both measurements?

Yes


No


5. GLOW PLUG CONTROL MODULE

1. Turn the ignition off.
2. Remove the jumper wire and install the ASD Relay.
3. Replace the Glow Plug Module in accordance with the service information.
4. Reconnect all connectors.
5. Turn the ignition on.
6. With the scan tool, erase PCM DTCs.
7. Perform several engine run cycles, turning the ignition off for at least 20 seconds between each engine run cycle.
8. With the scan tool, read the PCM DTCs.


Did this DTC return?

Yes


No