For 1990-2009 cars

### Circuit Description

The Stoplamp Switch is a normally open switch, when the brake pedal is depressed, the EBCM senses battery voltage. This allows the EBCM to determine the state of the brake lamp circuit.

### Conditions for Setting the DTC

• | EBCM detects battery voltage at all times.

• | EBCM never detects battery voltage from the stoplamp switch input circuit.

• | Both brake lamps are faulty.

### Action Taken When the DTC Sets

• | DTC C0161 is set.

• | ABS and TCS remains active.

### Conditions for Clearing the DTC

• | The condition responsible for setting the DTC no longer exists and the scan tool Clear DTCs function is used.

• | 100 ignition cycles pass with no DTC(s) detected.

### Diagnostic Aids

• | It is very important that a thorough inspection of the wiring and connectors be performed. Failure to carefully and fully inspect wiring and connectors may result in misdiagnosis, causing part replacement with reappearance of the malfunction.

• | Thoroughly inspect any circuitry that may be causing the complaint for the following conditions:

- | Backed out terminals

- | Improper mating

- | Broken locks

- | Improperly formed or damaged terminals

- | Poor terminal-to-wiring connections

- | Physical damage to the wiring harness

• | The following conditions may cause an intermittent malfunction:

- | A poor connection

- | Rubbed-through wire insulation

- | A broken wire inside the insulation

• | If an intermittent malfunction exists refer to Intermittents and Poor Connections in Wiring Systems for further diagnosis.

### Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. This step checks for voltage at the EBTCM.

2. This step checks the Stoplamp switch.

#### DTC C0161 ABS/TCS Brake Switch Circuit Malfunction

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
SCHEMATIC REFERENCE:

#### Electronic Traction Control Switch, ABS Indicator, and Stop Lamp Switch

1 | Was the Diagnostic System Check performed? | -- | Go to Step 2 | Go to Diagnostic System Check - ABS
2 | Observe the rear brake lamps. Are the brake lamps off? | -- | Go to Step 4 | Go to Step 3
3 | Disconnect the Stoplamp Switch connector. Are the brake lamps on? | -- | Go to Step 18 | Go to Step 12
4 | Press the brake pedal. Do the brake lights come on? | -- | Go to Step 5 | Go to Step 8
5 |

1. Turn the ignition switch to the OFF position.
2. Disconnect the EBCM connector C1.
3. Install the Universal Pinout Box using the J 39700-280 cable adapter to the EBCM harness connector only.
4. Using the DMM, measure the voltage at the Universal Pinout Box terminal 14 while an assistant presses the brake pedal.

Is the voltage within specifications?

Battery voltage

Go to Step 6

Go to Step 7

6 | Replace the EBCM. Refer to Electronic Brake and Traction Control Module Replacement . Is the replacement complete? | -- | Go to Diagnostic System Check - ABS | --
7 | Repair the open or high resistance in the stoplamp switch input circuit. Refer to Wiring Repairs in Wiring Systems. Is the circuit repair complete? | -- | Go to A Diagnostic System Check - ABS | --
8 | Check the HAZARD FUSE 12 in the Fuse Block. Is the fuse OK? | -- | Go to Step 9 | Go to Step 13
9 |

1. Disconnect the Stoplamp Switch connector.
2. Using the DMM, measure the voltage at the Stoplamp Switch harness connector terminal 1.

Is the voltage within specifications?

Battery voltage

Go to Step 11

Go to Step 10

10 | Repair the open in the stoplamp CKT between the stoplamp switch and the HAZARD FUSE 12. Refer to Wiring Repairs in Wiring Systems. Is the circuit repair complete? | -- | Go to Diagnostic System Check - ABS | --
11 | Connect a fused jumper wire between the Stoplamp Switch harness connector terminals 1 and 2. Do the brake lamps come on? | -- | Go to Step 12 | Go to Step 7
12 | Adjust or replace the Stoplamp Switch as necessary. Refer to the appropriate procedure.

• | Stop Lamp Switch Replacement in Hydraulic Brakes for replacement.

• | Stop Lamp Switch Adjustment in Hydraulic Brakes for adjustment.

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

13 |

1. Replace the HAZARD FUSE 12. (Do not press the brake pedal.)
2. Check the fuse.

Is the fuse OK?

--

Go to Step 15

Go to Step 14

14 | Repair the short to ground in the stoplamp circuit between the stoplamp switch and the HAZARD FUSE 12. Refer to Wiring Repairs in Wiring Systems. Is the circuit repair complete? | -- | Go to Diagnostic System Check - ABS | --
15 |

1. Press the brake pedal.
2. Check the HAZARD FUSE 12.

Is the fuse OK?

--

Go to Diagnostic System Check - ABS

Go to Step 16

16 |

1. Turn the ignition switch to the OFF position.
2. Disconnect the EBCM.
3. Replace the fuse.
4. Depress the brake pedal.
5. Check the HAZARD FUSE 12.

Is the fuse OK?

--

Go to Step 6

Go to Step 17

17 | Repair the short to ground in the stoplamp switch input circuit. Refer to Wiring Repairs in Wiring Systems. Is the circuit repair complete? | -- | Go to Diagnostic System Check - ABS | --
18 | Repair the stoplamp switch circuit for a short to voltage. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Diagnostic System Check - ABS | --