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6.(B29) BRAKE LAMP SWITCH SIGNAL CIRCUIT SHORTED TO GROUND
Measure the resistance between ground and the (B29) Brake Lamp
Switch Signal circuit at the Stop Lamp Switch harness connector.
Istheresistancebelow100ohms?
Ye s>>
Repair the short to ground in the (B29) Brake Lamp Switch
Signal circuit.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to
9 - ENGINE - STANDARD PROCEDURE)
No>>
Go To 7
7.(B29) BRAKE LAMP SWITCH SIGNAL LESS THAN 10.0 VOLTS
Connect the PCM harness connectors.
Connect the Brake Lamp Switch harness connector.
Brake pedal must be depressed in the next step.
Ignition on, engine not running.
Using a 12-volt test light connected to ground, probe the (B29) Brake Lamp Switch Signal circuit at the Brake Lamp
Switch harness connector.
Is the test light illuminated and bright?
Ye s>>
Go To 8
No>>
Replace or adjust the brake switch.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
8.PCM
NOTE: Before continuing, check the PCM harness connector terminals for corrosion, damage, or terminal
push out. Repair as necessary.
Using the schematics as a guide, inspect the wire harness and connectors. Pay particular attention to all Power and
Ground circuits.
If there are no possible causes remaining, view repair.
Repair
Replace and program the Powertrain Control Module per Service Information.
Perform the POWERTRAIN VERIFICATION TEST. (Refer to 9 - ENGINE - STANDARD PROCEDURE)
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*CANNOT SHIFT INTO REVERSE
For a complete wiring diagramRefer to Section 8W.
Page 1467 of 5267
Possible Causes
REVERSE LOCKOUT SOLENOID STUCK
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
Diagnostic Test
1.REVERSE LOCKOUT SOLENOID STUCK
Check for a mechanically stuck Reverse Lockout Solenoid. This will not seta DTC in the PCM, but will prevent
reverse gear engagement.
Is the solenoid stuck?
Ye s>>
Replace the Reverse Lockout Solenoid.
No>>
Te s t C o m p l e t e
Page 1468 of 5267
*CHECKING A/C SYSTEM OPERATION WITH NO DTCS
For a complete wiring diagramRefer to Section 8W.
Page 1469 of 5267

Possible Causes
A/C SELECT CIRCUIT OPEN
A/C SELECT IN HVAC
PCM
A/C REQUEST CIRCUIT OPEN
REFRIGERATION SYSTEM NOT PROPERLY CHARGED
HIGH PRESS CUT-OFF SWITCH
LOW PRESSURE SWITCH
A/CCLUTCHCOIL
A/C COMPRESSOR CLUTCH GROUND CIRCUIT OPEN
(C3) A/C CLUTCH RELAY OUTPUT CIRCUIT OPEN
FUSED B+ CIRCUIT OPEN
A/CCLUTCHRELAY
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 9 - ENGINE -
DIAGNOSIS AND TESTING)
Diagnostic Test
1.DTC AND COMMUNICATION PRESENT
Ignition on, engine not running.
Verify that communication with the HVAC and PCM is available over the BUS.
With the scan tool, check for DTCs in the PCM and HVAC module.
Are any A/C DTC’s or communication failures present?
Ye s>>
Diagnose the related DTC(s) or BUS failure before continuing.
Perform BODY VERIFICATION TEST - VER 1.
No>>
Go To 2
2.A/C SELECT CIRCUIT OPEN
Engine running.
With the scan tool, read the A/C Select status in the PCM.
Turn the A/C Switch on and off a few times.
Does the A/C Select state change?
Ye s>>
Go To 3
No>>
Go To 12
3.A/C REQUEST CIRCUIT OPEN
Engine Running.
Turn the A/C system on and the fan on high.
With the scan tool in Inputs/Outputs, read the A/C request state.
Does the A/C request state change?
Ye s>>
Go To 4
No>>
Repair the open in the A/C Request circuit.
Perform BODY VERIFICATION TEST - VER 1.
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4.REFRIGERATION SYSTEM NOT PROPERLY CHARGED
Turn the ignition off.
Verify that the Refrigerant System is properly charged per Service Procedure.
Is the Refrigerant System properly charged?
Ye s>>
Go To 5
No>>
Properly charge the Refrigerant System per Service Information.
Perform BODY VERIFICATION TEST - VER 1.
5.HIGH PRESSURE CUT-OFF SWITCH
Turn the ignition off.
Verify the High Pressure Cut-Off Switch operation per Service Information.
Is the High Pressure Cut-Off Switch OK?
Ye s>>
Go To 6
No>>
Replace the High Pressure Cut-Off Switch.
Perform BODY VERIFICATION TEST - VER 1.
6.LOW PRESSURE SWITCH
Turn the ignition off.
Verify the Low Pressure Switch operation per Service Information.
Is the Low Pressure Switch OK?
Ye s>>
Go To 7
No>>
Replace the Low Pressure Switch.
Perform BODY VERIFICATION TEST - VER 1.
7.A/C CLUTCH COIL
Ignition on, engine not running.
Disconnect the A/C Compressor Clutch harness connector.
Connect a test light between the ground circuit and the A/C Clutch Relay Output circuit.
With the scan tool, actuate the A/C Clutch Relay.
Does the test light illuminate brightly on and off with the relay actuation?
Ye s>>
Replace the A/C Clutch Coil.
Perform BODY VERIFICATION TEST - VER 1.
No>>
Go To 8
8.A/C COMPRESSOR CLUTCH GROUND CIRCUIT OPEN
Turn the ignition off.
Disconnect the A/C Clutch harness connector.
NOTE: Check connectors - Clean/repair as necessary.
Measure the resistance between ground and the A/C Compressor Clutch ground circuit in the A/C Clutch harness
connector.
Is the resistance below 5.0 ohms?
Ye s>>
Go To 9
No>>
Repair the open in the A/C Compressor Clutch ground circuit.
Perform BODY VERIFICATION TEST - VER 1.
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9.(C3) A/C CLUTCH RELAY OUTPUT CIRCUIT OPEN
Turn the ignition off.
Disconnect the A/C Clutch harness connector.
Remove the A/C Clutch Relay.
NOTE: Check connectors - Clean/repair as necessary.
Measure the resistance of the (C3) A/C Clutch Relay Output circuit betweenthe IPM and the A/C Clutch Coil.
Is the resistance below 5.0 ohms?
Ye s>>
Go To 10
No>>
Repair the open in the (C3) A/C Clutch Relay Output circuit.
Perform BODY VERIFICATION TEST - VER 1.
10.(A17) FUSED B+ CIRCUIT OPEN
Turn the ignition off.
Remove the A/C Clutch Relay.
NOTE: Check connectors - Clean/repair as necessary.
Measure the voltage of the Fused B+ circuit at the A/C Clutch Relay connector.
Is the voltage above 11.0 volts?
Ye s>>
Go To 11
No>>
Repair the open in the Fused B+ circuit. The open may be in the IMP.
Perform BODY VERIFICATION TEST - VER 1.
11 .A/C CLUTCH RELAY
If there are no possible causes remaining, view repair.
Repair
Replace the A/C Clutch Relay.
Perform BODY VERIFICATION TEST - VER 1.
12.A/CSELECTSWITCHSTATUSINHVAC
Ignition on, engine not running.
With the scan tool in the HVAC, under the Monitors screen, read the A/C Select Switch state.
While monitoring the scan tool screen, turn the A/C switch on and off a few times.
Does the A/C Select State change on the HVAC Monitors screen.
Ye s>>
Check for any related TSBs. Replace and program the PCM in accordance with the Service Information
as long as no BUS problems exist.
Perform BODY VERIFICATION TEST - VER 1.
No>>
Replace the A/C-Heater Control module.
Perform BODY VERIFICATION TEST - VER 1.
Page 1472 of 5267
*CHECKING CHARGING SYSTEM OPERATION WITH NO DTCS
For a complete wiring diagramRefer to Section 8W.