LEMON Manuals: Even more car manuals for everyone
Home >> Jeep >> 2005 >> Wrangler Rubicon, Standard >> Repair and Diagnosis >> External Pages >> Different car >> Section 490 (Powertrain Diagnostic Procedures - Diesel) >> Diagnostic Information And Procedures >> DRIVEABILITY - Diesel - Diagnostic Tests >> P0504-Brake Switch Signal Circuits Plausibility With Redundant Contact >> 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 PROCEDURES - P0504-BRAKE SWITCH SIGNAL CIRCUITS PLAUSIBILITY WITH REDUNDANT CONTACT

TEST ACTION APPLICABILITY
1
NOTE: If the ECM detects and stores a DTC, the ECM also stores the engine/vehicle operating conditions under which the DTC was set. Some of these conditions are displayed on the DRB 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.
Turn the ignition on.While observing the PRIMARY BRAKE SWITCH status on the DRB display, press and release the brake pedal several times.Does the DRB display PRIMARY BRAKE SWITCH: PRESSED and RELEASED for the appropriate pedal position?Yes --> Go To 2No --> Go To 11		 All
2 Turn the ignition on.
While observing the SECONDARY BRAKE SWITCH status on the DRB display, press and release the brake pedal several times.
Does the DRB display SECONDARY BRAKE SWITCH: PRESSED and RELEASED for the appropriate pedal position
Yes --> Go To 3
No --> Go To 4		 All
3
WARNING: WHEN THE ENGINE IS OPERATING, DO NOT STAND IN A DIRECT LINE WITH THE FAN. DO NOT PUT YOUR HANDS NEAR THE PULLEYS, BELTS OR FAN. DO NOT WEAR LOOSE CLOTHING.
NOTE: The conditions that set the DTC are not present at this time. The following list may help in identifying the intermittent condition.
With the engine running at normal operating temperature, monitor the DRB parameters related to the DTC while wiggling the wiring harness. Look for parameter values to change and/or a DTC to set.Review the DTC When Monitored and Set Conditions. If possible, try to duplicate the conditions under which the DTC was set.Refer to any Technical Service Bulletins (TSB) that may apply.Visually inspect the related wiring harness. Look for any chafed, pierced, pinched, or partially broken wires.Visually inspect the related wiring harness connectors. Look for broken, bent, pushed out, or corroded terminals.Were any of the above conditions present?Yes --> Repair as necessary.Perform ROAD TEST VERIFICATION - VER-2 .No --> Test Complete.		 All
4 Turn the ignition off.
Disconnect the Brake Lamp Switch harness connector.
Turn the ignition on.
Measure the voltage between the Brake Switch Sense circuit and ground.
Is the voltage above 9.0 volts?
Yes --> Go To 5
No --> Go To 8		 All
5 Disconnect the Brake Lamp Switch harness connector.
Turn the ignition on.
While monitoring the SECONDARY BRAKE SWITCH status with the DRB, connect a jumper wire between ground and the Secondary Brake Switch Sense circuit.
Does the DRB display change from PRESSED to RELEASED?
Yes --> Adjust or replace the Brake Lamp Switch in accordance with the Service Information.
Perform ROAD TEST VERIFICATION - VER-2 .
No --> Go To 6		 All
6 Turn the ignition off.
Disconnect the Brake Lamp Switch harness connector.
Measure the resistance between ground and the Secondary Brake Switch Ground circuit.
Is the resistance below 10.0 ohms?
Yes --> Go To 7
No --> Repair the Brake Switch Sense Ground circuit for an open.
Perform ROAD TEST VERIFICATION - VER-2 .		 All
7 If there are no possible causes remaining, view repair.
Repair
Replace and program the Engine Control Module in accordance with the Service Information.
Perform ROAD TEST VERIFICATION - VER-2 .		 All
8 Turn the ignition off.
Disconnect the Brake Lamp Switch harness connector.
Disconnect the ECM harness connectors.
Measure the resistance between ground and the Brake Switch Sense circuit.
Is the resistance above 1000 ohms?
Yes --> Go To 9
No --> Repair the Brake Switch Sense circuit for a short to ground.
Perform ROAD TEST VERIFICATION - VER-2 .		 All
9 Turn the ignition off.
Disconnect the Brake Lamp Switch harness connector.
Disconnect the ECM harness connectors.
Measure the resistance of the Brake Switch Sense circuit.
Is the resistance below 10.0 ohms?
Yes --> Go To 10
No --> Repair the Brake Switch Sense circuit for an open.
Perform ROAD TEST VERIFICATION - VER-2 .		 All
10 If there are no possible causes remaining, view repair.
Repair
Replace and program the Engine Control Module in accordance with the Service Information.
Perform ROAD TEST VERIFICATION - VER-2 .		 All
11 Disconnect the Brake Lamp Switch harness connector.
Using a 12-volt test light connected to ground, check the Fused B+ circuit.
Does the test light illuminate brightly?
Yes --> Go To 12
No --> Repair the Brake Lamp Switch Fused B+ circuit for an open.
Perform ROAD TEST VERIFICATION - VER-2 .		 All
12 Disconnect the Brake Lamp Switch harness connector.
Turn the ignition on.
While monitoring the PRIM BRAKE SWITCH status with the DRB, connect a jumper wire between the Brake Lamp Switch Output circuit and the Fused B(+) circuit.
Does the DRB display change from RELEASED to PRESSED?
Yes --> Adjust or replace the Brake Lamp Switch in accordance with the Service Information.
Perform ROAD TEST VERIFICATION - VER-2 .
No --> Go To 13		 All
13 Turn the ignition off.
Disconnect the Brake Lamp Switch harness connector.
Disconnect the ECM harness connectors.
Remove the ASD Relay from the PDC.
Connect a jumper wire between cavity 30 and cavity 87 of the ASD Relay connector.
Turn the ignition on.
Measure the voltage between the Brake Lamp Switch Output circuit and ground.
Is the voltage above 1.0 volt?
Yes --> Repair the Brake Lamp Switch Output circuit for a short to voltage.
Perform ROAD TEST VERIFICATION - VER-2 .
No --> Go To 14		 All
14 Turn the ignition off.
Disconnect the Brake Lamp Switch harness connector.
Disconnect the ECM harness connectors.
Measure the resistance of the Brake Lamp Switch Output circuit.
Is the resistance below 10.0 ohms?
Yes --> Replace and program the Engine Control Module in accordance with the Service Information.
Perform ROAD TEST VERIFICATION - VER-2 .
No --> Repair the Brake Lamp Switch Output circuit for an open.
Perform ROAD TEST VERIFICATION - VER-2 .		 All
scientia non olet · About LEMON Manuals