DTC C1294 Brake Lamp Switch Circuit Always Active. Oldsmobile Eighty Eight 1999

For 1990-2009 cars only

Makes 🢒 Oldsmobile 🢒 1999 🢒 Eighty Eight 🢒 Brakes 🢒 Antilock Brake System 🢒 DTC C1294 Brake Lamp Switch Circuit Always Active

ABS Components
Cell 44: PWR, GND, and Stoplamp/BTSI Switch
Handling ESD Sensitive Parts Notice
Cell 10: MISC LGT, COOL FNS, C/LTR/RDO/CLSTR/MISC, IGN SW, RR DEFOG/PWRSEAT, ABS SOL, and ABS MOT Fuses
Cell 10: BRK/HZRD LPS, FOG LPS, CTSY LP/PWR MIR, and PARKLPS/INT LPS Fuses

Circuit Description

This DTC occurs when the internal self-checking safety logic has determined that the stoplamp/BTSI switch is continuously on. The TCS cannot be activated when the stoplamp/BTSI switch is on.

Conditions for Setting the DTC

The DTC sets if the following occur:

•	The vehicle speed is greater than 40 km/h (25 mph).

•	The brake was never off during 2 consecutive drive cycles.

Action Taken When the DTC Sets

•	A malfunction DTC is stored.

•	The TCS is disabled.

•	The TRACTION OFF indicator is turned ON.

•	The ABS remains functional.

Conditions for Clearing the DTC

•	The condition for the DTC is no longer present and you used the scan tool Clear DTC function.

•	The EBCM/EBTCM does not detect the DTC in 50 drive cycles.

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.

•	An intermittent malfunction can be caused by poor connections, broken insulation, or a wire that is broken inside the insulation.

•	If an intermittent malfunction exists, refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.

•	This condition may be cause by the following:

-	A short to voltage in the stoplamp/BTSI switch circuit.

-	A misadjusted or shorted stoplamp/BTSI switch.

-	A pedal that is binding.

Test Description

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

This step inspects for a short to voltage.

Step

Action

Value(s)

Yes

Did you perform the ABS Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - ABS

Observe the rear brake lamps.

Are the rear brake lamps off?

Go to Step 4

Go to Step 3

Disconnect the stoplamp/BTSI switch connector.

Are the brake lamps on?

Go to Step 6

Go to Step 7

Disconnect the EBCM/EBTCM harness connector.
Install the J 39700 universal pinout box using the J 39700-25 cable adapter to the EBCM/EBTCM harness connector only.
Use the J 39200 DMM in order to measure the voltage between the J 39700 terminal 3 and ground.

Is the voltage more than the specified value?

1 V

Go to Step 6

Go to Step 5

Turn OFF the ignition.
Inspect CKT 17 and the EBCM/EBTCM harness connector for damage which may result in a short to voltage with all connectors connected.
Reconnect all connectors.
Drive the vehicle for 3 drive cycles. A drive cycle consists of the following procedures:

•	Start the engine.

•	Drive above 40 km/h (25 mph) and back to 0 km/h (0 mph).

•	Turn OFF the ignition.

Was DTC C1294 set in the last three drive cycles?

Go to Step 8

Go to Diagnostic System Check - ABS

Repair the short to voltage in CKT 17 (WHT) or CKT 20 (LT BLU). Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Diagnostic System Check - ABS

Adjust or replace the stoplamp/BTSI switch as needed. Refer to Stop Lamp Switch Adjustment or Stop Lamp Switch Replacement in Hydraulic Brakes.

Did you complete the repair?

Go to Diagnostic System Check - ABS

Replace the EBTCM. Refer to Electronic Brake Control Module Replacement .

Did you complete the repair?

Go to Diagnostic System Check - ABS