FREE REPAIR MANUALS & LABOR GUIDES 1982-2013 Vehicles
Courtesy of Operation CHARM: Car repair manuals for everyone.
Home >> Ford >> 2009 >> Mustang V6-4.0L >> Repair and Diagnosis >> Brakes and Traction Control >> Antilock Brakes / Traction Control Systems >> Testing and Inspection >> Pinpoint Tests >> Pinpoint Test E: DTC C1446 - Brake Switch Circuit Failure

Pinpoint Test E: DTC C1446 - Brake Switch Circuit Failure




Anti-Lock Control

Pinpoint Tests

Pinpoint Test E: DTC C1446 - Brake Switch Circuit Failure

Refer to Wiring Diagram Set 42, Vehicle Dynamic Systems for schematic and connector information. Diagrams By Number

Normal Operation

The normally-closed Brake Pedal Position (BPP) switch (also known as the speed control deactivation switch) receives fused battery voltage from Bussed Electrical Center (BEC) fuse 47 (15A) along circuit 391 (RD/YE) when the ignition key is turned to the RUN position. This voltage is sent through the BPP switch to the ABS module and the PCM along circuit 535 (LB/RD). When the brake pedal is applied, the BPP opens and the voltage signal is no longer referenced by the ABS module and PCM.

When the fluid level in the brake master cylinder reservoir reaches a predetermined level, the brake fluid level switch closes and voltage is sent to the Smart Junction Box (SJB). The SJB then sends a message to the ABS module along the High Speed Controller Area Network (HS-CAN) bus network.

- DTC C1446 Brake Switch Circuit Failure - If during normal operation the ABS module determines that the BPP information is invalid when compared to other inputs (brake pressure transducer and wheel speed sensors) or if the brake pedal message is missing completely, DTC C1446 will be set. Also, a low brake fluid level in the master cylinder reservoir or an open, short to ground or short to voltage in the brake fluid level switch that the SJB interprets as a low fluid condition will cause DTC C1446 to be set.

This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- BPP switch
- ABS module



PINPOINT TEST E: DTC C1446 - BRAKE SWITCH CIRCUIT FAILURE

NOTICE: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use standard multi-meter probes.

-------------------------------------------------
E1 MONITOR THE RED BRAKE WARNING INDICATOR


- Ignition ON.
- Observe the red brake warning indicator while turning the ignition switch from OFF to RUN.
- Does the indicator illuminate for a brief period and then extinguish?

Yes
GO to E2.

No
REFER to Instrument Panel, Gauges and Warning Indicators to diagnose the red brake warning indicator.

-------------------------------------------------
E2 CHECK THE ABS MODULE AND THE SJB FOR COMMUNICATION DTCs


- Connect the scan tool.
- Enter the following diagnostic mode on the scan tool: Self Test ABS Module.
- Retrieve and record any ABS module communication DTCs.
- Enter the following diagnostic mode on the scan tool: Self Test SJB.
- Retrieve and record any SJB communication DTCs.
- Are any communication DTCs present in the ABS module and/or the SJB?

Yes
For ABS module communication DTCs, REFER to the ABS Module DTC Chart. ABS Module DTC Chart

For SJB communication DTCs, REFER to the Master DTC Chart in Body Control Systems. Diagnostic Trouble Code Descriptions

No
GO to E3.

-------------------------------------------------
E3 CHECK FOR BPP SWITCH VOLTAGE TO THE ABS MODULE


- Ignition OFF.
- Disconnect: ABS Module C135.
- Ignition ON.
- While pressing and releasing the brake pedal, measure the voltage between ABS module C135-6, circuit 535 (LB/RD), harness side and ground.




- Is the voltage greater than 10 volts with the pedal released and 0 volt with the pedal pressed?

Yes
GO to E12.

No
GO to E4.

-------------------------------------------------
E4 ISOLATE THE BPP SWITCH


- Ignition OFF.
- Disconnect: BPP Switch C278 (also known as the speed control deactivator switch).
- While pressing and releasing the brake pedal, measure the resistance between BPP switch connector C278 pin-1, component side, and BPP switch C278 pin-2, component side.
- Is the resistance greater than 10,000 ohms with the pedal pressed and less than 5 ohms with the brake pedal released?

Yes
GO to E5.

No
INSTALL a new BPP switch. CLEAR the DTC. REPEAT the self-test.

-------------------------------------------------
E5 CHECK CIRCUIT 535 (LB/RD) FOR AN OPEN


- Ignition OFF.
- Disconnect: PCM C175b.
- Measure the resistance between ABS module C135-6, circuit 535 (LB/RD), harness side and BPP switch C278-1, circuit 535 (LB/RD), harness side.




- Is the resistance less than 5 ohms?

Yes
GO to E6.

No
REPAIR circuit 535 (LB/RD). CLEAR the DTC. REPEAT the self-test.

-------------------------------------------------
E6 CHECK CIRCUIT 535 (LB/RD) FOR A SHORT TO GROUND


- Measure the resistance between ABS module C135-6, circuit 535 (LB/RD), harness side and ground.




- Is the resistance greater than 10,000 ohms?

Yes
GO to E7.

No
REPAIR circuit 535 (LB/RD). CLEAR the DTC. REPEAT the self-test.

-------------------------------------------------
E7 CHECK CIRCUIT 535 (LB/RD) FOR A SHORT TO VOLTAGE


- Ignition ON.
- Measure the voltage between ABS module C135-6, circuit 535 (LB/RD), harness side and ground.




- Is any voltage present?

Yes
REPAIR circuit 535 (LB/RD). CLEAR the DTC. REPEAT the self-test.

No
GO to E8.

-------------------------------------------------
E8 CHECK THE PCM FOR A SHORT TO GROUND


- Ignition OFF.
- Connect: PCM C175b.
- Measure the resistance between ABS module C135-6, circuit 535 (LB/RD), harness side and ground.




- Is the resistance greater than 10,000 ohms?

Yes
GO to E9.

No
INSTALL a new PCM. CLEAR the DTC. REPEAT the self-test.

-------------------------------------------------
E9 CHECK THE PCM FOR A SHORT TO VOLTAGE


- Ignition ON.
- Measure the voltage between ABS module C135-6, circuit 535 (LB/RD), harness side and ground.




- Is any voltage present?

Yes
INSTALL a new PCM. CLEAR the DTC. REPEAT the self-test.

No
GO to E10.

-------------------------------------------------
E10 CHECK CIRCUIT 391 (RD/YE) FOR AN OPEN


- Ignition OFF.
- Disconnect: BEC C1035a.
- Measure the resistance between BPP switch C278-2, circuit 391 (RD/YE), harness side and BEC C1035a-C2, circuit 391 (RD/YE), harness side.




- Is the resistance less than 5 ohms?

Yes
GO to E11.

No
VERIFY BEC fuse 47 (15A) is OK. If OK, REPAIR circuit 391 (RD/YE). CLEAR the DTC. REPEAT the self-test.

-------------------------------------------------
E11 CHECK CIRCUIT 391 (RD/YE) FOR A SHORT TO GROUND


- Measure the resistance between BPP switch C278-2, circuit 391 (RD/YE), harness side and ground.




- Is the resistance greater than 10,000 ohms?

Yes
INSTALL a new BPP switch. CLEAR the DTCs.
REPEAT the self-test.

No
REPAIR circuit 391 (RD/YE). CLEAR the DTC. REPEAT the self-test.

-------------------------------------------------
E12 CHECK FOR CORRECT ABS MODULE OPERATION


- Ignition OFF.
- Disconnect: ABS Module C135.
- Check the ABS module connector for:
- corrosion.
- pushed-out pins.
- spread terminals.
- Connect: ABS Module C135.
- Make sure the ABS module connector seats correctly, then operate the system and verify if the concern is still present.
- Is the concern still present?

Yes
INSTALL a new ABS module. REFER to Anti-Lock Brake System (ABS) Module Service and Repair. CLEAR the DTCs. REPEAT the self-test.

No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test with the brake pedal not applied.

-------------------------------------------------
pro multis Credits:Operation CHARM About Operation CHARM