C1088

C1088 - BRAKE LAMP SWITCH OUTPUT CIRCUIT LOW





For a complete wiring diagram Refer to Diagrams/Electrical.

- When Monitored:

With the ignition switch on.

- Set Condition:

The Multi-Purpose Module (Police And Taxi Interface Module-PTIM) has detected the Brake Lamp Switch Sense circuit below a calibrated value.





1.CHECK FOR ANY OF THE FOLLOWING ACTIVE DTCS

With the scan tool, read all active DTCs from all modules.

NOTE: Check for FCM configuration, CAN B or C hardware electrical, VIN Missing/Mismatch, battery or ignition related DTCs.

Does the scan tool display any active DTCs to the conditions listed above?

Yes

- Diagnose and repair the DTC.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

No

- Go To 2.

Diagnostic Test

2.CHECK FOR ACTIVE DTC

With the scan tool, read the active DTCs.

Erase the DTCs.

Turn the ignition off, wait 10 seconds, then turn the ignition on.

With the scan tool, read the active DTC's.

Does the scan tool display this DTC as active?

Yes

- Go To 3.

No

- If the DTC is stored, check for an intermittent condition. Visually inspect the related wiring harness connectors. Look for broken, bent, pushed out, or corroded terminals, and repair any obvious problems.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

3.CHECK THE (W520) BRAKE LAMP SWITCH SENSE CIRCUIT FOR A SHORT TO GROUND





Turn the ignition off.

Disconnect the Multi-Purpose Module (Police And Taxi Interface Module-PTIM) C2 harness connector.

Measure the resistance of the (W520) Brake Lamp Switch Sense circuit between ground and the Multi-Purpose Module (Police And Taxi Interface Module-PTIM) C2 harness connector.

Is the resistance below 5.0 ohms?

Yes

- Go To 4.

No

- Go To5.

4. ISOLATE THE SHORT TO GROUND�IN THE (W520) BRAKE LAMP SWITCH SENSE CIRCUIT





Turn the ignition off.

Disconnect the Multi-Purpose Module (Police And Taxi Interface Module-PTIM) 24 way harness connector (aftermarket light/siren controller side).

Measure the resistance of the (W520) Brake Lamp Switch Sense circuit between ground and the Multi-Purpose Module (Police And Taxi Interface Module-PTIM) C2 harness connector.

Is the resistance below 5.0 ohms?

Yes

- Repair the (W520) Brake Lamp Switch Sense circuit for a short to ground.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

No

- Refer to electrical diagnostics for the aftermarket light/siren controller, and repair or replace the aftermarket light/siren controller.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

5.CHECK THE MULTI-PURPOSE MODULE (POLICE AND TAXI INTERFACE MODULE-PTIM)

Turn the ignition off.

Disconnect all Multi-Purpose Module (Police And Taxi Interface Module-PTIM) and aftermarket light/siren controller harness connectors.

Check for damaged or corroded pins, pinched wires, or damaged connectors, and repair any obvious problems.

Connect all Multi-Purpose Module (Police And Taxi Interface Module-PTIM) and aftermarket light/siren controller harness connectors.

Turn the ignition on.

With the scan tool monitor active codes as you work through the following step.

Wiggle the wiring harness and connectors of the Multi-Purpose Module (Police And Taxi Interface Module-PTIM) and aftermarket light/siren controller.

If only stored codes return continue the test until the problem area has been isolated, and repair any obvious problems.

Is DTC C1088 - BRAKE LAMP SWITCH OUTPUT CIRCUIT LOW still displayed?

Yes

- Replace the Multi-Purpose Module (Police And Taxi Interface Module-PTIM).
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test

No

- Repair is complete. The problem may have been caused by a loose or corroded terminal.
- Perform BODY VERIFICATION TEST - VER 1. Body Verification Test