2012 Jeep Wrangler JK Factory Service Manual 28 - DTC-Based Diagnostics

P067A-CYLINDER 4 GLOW PLUG CIRCUIT LOW

P067A-CYLINDER 4 GLOW PLUG CIRCUIT LOW



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

(A208) GLOW PLUG 4 CONTROL CIRCUIT SHORTED TO GROUND
(A208) GLOW PLUG 4 CONTROL CIRCUIT SHORTED TO VOLTAGE
GLOW PLUG 4
GLOW PLUG MODULE

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


1. CHECK FOR ACTIVE DTC


1. Ignition on, engine not running.
2. With the scan tool, erase DTCs in the PCM.
3. Perform several ignition cycles leaving the ignition on for at least 10 seconds then off for 10 seconds.
4. With the scan tool, read the PCM DTCs.


Did this DTC return?

Yes


No


2. CHECK THE (A208) GLOW PLUG 4 CONTROL CIRCUIT FOR A SHORT TO GROUND



1. Turn the ignition off.
2. Disconnect the Glow Plug 4 harness connector.
3. Disconnect the Glow Plug Module harness connector.
4. Measure the resistance between ground and the (A208) Glow Plug 4 Control circuit at the Glow Plug 4 harness connector.


Is the resistance below 10k Ohms?

Yes


No


3. CHECK THE (A208) GLOW PLUG 4 CONTROL CIRCUIT FOR A SHORT TO VOLTAGE



1. Turn the ignition on.
2. Measure the voltage of the (A208) Glow Plug 4 Control circuit at the Glow Plug 4 harness connector.


Is there voltage present on the (A208) Glow Plug 4 Control circuit?

Yes


No


4. GLOW PLUG 4


1. Turn the ignition off.
2. Replace Glow Plug 4 in accordance with the service information.
3. Turn the ignition on.
4. With the scan tool, erase PCM DTCs.
5. Perform several ignition key cycles leaving the ignition on for at least 10 seconds per cycle.
6. With the scan tool, read PCM DTCs.


Does the scan tool display this DTC?

Yes


No


5. GLOW PLUG MODULE


1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Glow Plugs and the Glow Plug Module.
2. Look for any chafed, pierced, pinched, or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals.
4. Perform any Technical Service Bulletins that may apply.


Were any problems found?

Yes


No