GM Service Manual Online
For 1990-2009 cars only

Object Number: 393797  Size: MF
ABS Components
Antilock Brake System Schematics
Power Distribution Schematics
Cruise Control Schematics
Exterior Lights Schematics
Handling Electrostatic Discharge Sensitive Parts Notice

Circuit Description

The Stoplamp Switch is a normally open switch. When the brake pedal is depressed the EBCM/EBTCM senses battery voltage. This allows the EBCM/EBTCM to determine the state of the brake lamps. A brake switch circuit open will result in a modified ABS entrance criteria and possibly false settings of excessive wheel speed variation codes (C1225 thru C1228).

Conditions for Setting the DTC

    • The EBCM/EBTCM senses an open circuit condition for 2 seconds or more in the brake switch input circuit.
    • The EBCM/EBTCM senses an open circuit condition for 2 seconds or more in all brake lamps.
    • The EBCM/EBTCM senses an open circuit condition for 2 seconds or more in all brake lamp grounds.

Action Taken When the DTC Sets

    • A malfunction DTC is stored
    • TCS is disabled.
    • Traction Control indicator is turned on.
    • ABS remains functional.

Conditions for Clearing the DTC

    • Condition for DTC is no longer present and scan tool clear DTC function is used.
    • 100 ignition cycles have passed with no DTCs detected.

Diagnostic Aids

    • Possible causes:
       - Stoplamp switch input circuit open.
       - All brake lamps open.
       - Open brake lamp ground.
       - Circuit has a wiring problem, terminal corrosion, or poor connections.
    • 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.
    • If an intermittent malfunction exists refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.

DTC C1295 Brake Lamp Switch Circuit Open

Step

Action

Value(s)

Yes

No

1

Was the Diagnostic System Check performed?

--

Go to Step 2

Go to Diagnostic System Check - ABS

2

Press the brake pedal.

Do all of the brake lights illuminate?

--

Go to Step 3

Go to Exterior Lights System Check in Lighting Systems

3

Inspect both the EBCM/EBTCM and harness connector for the following conditions:

    • Terminal damage
    • Poor terminal contact
    • Terminal corrosion

Are there signs of terminal damage, poor terminal contact, or terminal corrosion?

--

Go to Step 4

Go to Step 5

4

Replace all of the terminals or the connector that exhibits signs of damaged terminals, poor terminal contact, or terminal corrosion.

Is the repair complete?

--

Go to Step 5

--

5

  1. Turn the Ignition switch to the OFF position.
  2. Disconnect the Stoplamp switch connector C1.
  3. Install the J 39700 Universal Pinout Box using J 39700-99 Cable Adapter to the EBCM/EBTCM harness connector only.
  4. Using a DMM, measure the resistance between the Universal Pinout Box terminal C7 and the stoplamp switch connector C1 terminal B.

Is the resistance within the range specified in the value(s) column?

0-2 ohms

Go to Step 7

Go to Step 6

6

Repair open or high resistance in CKT 17 between the stoplamp switch connector C1 and the EBCM/EBTCM. Refer to Wiring Repairs in Wiring Systems.

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

7

Replace the EBCM/EBTCM. Refer to Electronic Brake Control Module/Electronic Brake and Track Control Module Replacement .

Is the replacement complete?

--

Go to Diagnostic System Check - ABS

--