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Home >> Jeep >> 2005 >> Wrangler Rubicon, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 491 (Body Diagnostic Procedures) >> Diagnostic Information And Procedures >> Electrically Heated Systems >> Symptom: REAR DEFOGGER RELAY CONTROL CIRCUIT OPEN/SHORT TO GROUND >> Diagnostic Procedure

Diagnostic Procedure

WARNING: This page is about a different car, the 2005 Jeep Liberty. However, it is still accessible from the selected car via links, so may be relevant.
DIAGNOSTIC PROCEDURE - REAR DEFOGGER RELAY CONTROL CIRCUIT OPEN/SHORT TO GROUND

TEST ACTION APPLICABILITY
1 Turn the ignition on.
With the DRBIII®, erase DTCs.
Attempt to operate the Rear Window Defogger.
With the DRBIII®, read DTCs.
Does the DRBIII® display REAR WINDOW DEFOGGER RELAY CONTROL CIRCUIT OPEN/SHORT TO GROUND?
Yes --> Go To 2
No --> Problem is intermittent and not present at this time. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors and repair as necessary. Ensure the relay is completely plugged in.
Perform BODY VERIFICATION TEST - VER 1  .
All
2 Check Junction Block fuse 39.
Is the fuse open.
Yes --> Check for a short to ground and replace the Junction Block fuse.
Perform BODY VERIFICATION TEST - VER 1  .
No --> Go To 3
All
3 Turn the ignition on.
Using a 12-volt test light connected to ground, check the Fused Ignition Switch Output circuit at Fuse 39.
The test light must illuminate brightly. Compare the brightness to that of a direct connection to the battery.
Does the test light illuminate brightly?
Yes --> Go To 4
No --> Repair the open Fused Ignition Switch Output circuit as necessary.
Perform BODY VERIFICATION TEST - VER 1  .
All
4 Remove the Rear Window Defogger Relay from the Junction Block.
Install fuse if previously removed.
Install a substitute relay in place of the Rear Window Defogger Relay.
With the DRBIII®, erase DTCs.
Attempt to operate the Rear Window Defogger.
With the DRBIII®, read DTCs.
Does the DRBIII® display REAR WINDOW DEFOGGER RELAY CONTROL CIRCUIT OPEN/SHORT TO GROUND?
Yes --> Go To 5
No --> Replace the original relay.
Perform BODY VERIFICATION TEST - VER 1  .
All
5 Turn the ignition off.
Remove the Rear Window Defogger Relay from the Junction Block.
Remove the Body Control Module from the Junction Block.
NOTE: Ensure the Junction Block connectors are reconnected at this time.

Measure the resistance between ground and the Rear Window Defogger Relay Control circuit in the relay connector of the Junction Block.
Is the resistance below 100.0 ohms?
Yes --> Replace the Junction Block.
Perform BODY VERIFICATION TEST - VER 1  .
No --> Go To 6
All
6 Turn the ignition off.
Remove the Rear Window Defogger Relay from the Junction Block.
Remove the Body Control Module from the Junction Block.
Measure the resistance of the Rear Window Defogger Relay Control circuit between the Relay connector and the Junction Block - BCM connector.
Is the resistance below 2.0 ohms?
Yes --> Go To 7
No --> Replace the Junction Block.
Perform BODY VERIFICATION TEST - VER 1  .
All
7 If there are no possible causes remaining, view repair.
Repair
Replace the Body Control Module.
Perform BODY VERIFICATION TEST - VER 1  .
All