DTC C1291 Open Brake Lamp Switch Contacts During Deceleration. Pontiac Trans Sport Ext. 1998

For 1990-2009 cars only

Makes 🢒 Pontiac 🢒 1998 🢒 Trans Sport Ext. 🢒 Brakes 🢒 Antilock Brake System 🢒 DTC C1291 Open Brake Lamp Switch Contacts During Deceleration

ABS Components
Antilock Brake System Schematics
Power Distribution Schematics
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Exterior Lights Schematics

Circuit Description

DTC C1291 detects an open brake switch in the non-ABS mode. The EBCM/EBTCM looks for deceleration rates that may indicate braking action. The EBCM/EBTCM verifies braking action by repeating the method for finding deceleration rates that indicate braking action several times. In each case, the ABS will not be available because the EBCM/EBTCM does not see the brake switch input.

Conditions for Setting the DTC

DTC C1291 can set if three deceleration cycles within the specified rate occur during the current ignition cycle with the brake switch off.

Action Taken When the DTC Sets

•	A malfunction DTC stores.

•	The ABS/TCS disables.

•	The amber ABS/TCS warning indicators turns on.

Conditions for Clearing the DTC

•	The condition responsible for setting the DTC no longer exists and the Scan Tool Clear DTC function is used.

•	100 drive cycles pass with no DTC detected.

Diagnostic Aids

Use the enhanced diagnostic function of the Scan Tool in order to measure the frequency of the malfunction. Refer to the Scan Tool manual Scan Tool Diagnostics for the procedure. Use the Data List of the Scan Tool verify proper brake switch operation. The Data List should display the brake switch as the brake is applied within 25 mm (1.0 in) of brake pedal travel.

Thoroughly inspect any circuitry that may cause the intermittent complaint for the following conditions:

•	Rubbed-through wire insulation

•	A broken wire inside the insulation

•	Backed out terminals

•	Improper mating

•	Broken locks

•	Improperly formed or damaged terminals

•	Poor terminal-to-wiring connections

•	Physical damage to the wiring harness

Important: Zero the J 39200 test leads before making any resistance measurements.

DTC C1291 Open Brake Lamp Sw Contacts During Decel

Step

Action

Value(s)

Yes

Was the Diagnostic System Check performed?

Go to Step 2

Go to Diagnostic System Check

Turn the ignition switch to the RUN position, engine OFF.
Install a Scan Tool .
Use the Scan Tool in order to inspect for DTCs.

Is DTC C1295 set as either a current and/or history DTC?

Go to DTC C1295 Brake Lamp Switch Circuit Open

Go to Step 3

Select Data List on the Scan Tool
Select Brake Switch Position on the Scan Tool
Apply light pressure to the brake pedal while monitoring the position of the brake switch on the Scan Tool

Does the Scan Tool indicate that the brake switch is on within 25 mm (1.0 in) of brake pedal travel?

Go to Step 23

Go to Step 4

Apply firm pressure to the brake pedal.
Observe the rear brake lamps.

Are the rear brake lamps on?

Go to Step 5

Go to Step 8

Turn the ignition switch to the OFF position.
Disconnect the 24-way EBCM/EBTCM connector C1.
Turn the ignition switch to the RUN position, engine OFF.
Apply firm pressure to the brake pedal.
Use the J 39200 in order to measure the voltage between the 24-way EBCM/EBTCM harness connector C1 terminal B9 and ground.

Is the voltage equal to or greater than the specified voltage?

10.0V

Go to Step 6

Go to Step 15

Inspect the 24-way EBCM/EBTCM connector C1 and the 24-way EBCM/EBTCM harness connector C1 for the following conditions:

•	Terminal damage

•	Poor terminal contact

•	Terminal corrosion

Is there poor terminal contact, terminal corrosion, or damaged terminals?

Go to Step 16

Go to Step 7

Reconnect the 24-way EBCM/EBTCM connector C1.
Test drive the vehicle and perform a brake stop from 32 km/h (20 mph) engaging the ABS.
Use the Scan Tool in order to inspect for DTCs.

Does DTC C1291 set as a current DTC?

Go to Step 22

Go to Step 23

Use the J 39200 in order to measure the voltage between the stoplamp switch harness connector C1 terminal A and ground.

Is the voltage equal to or greater than the specified voltage?

10.0V

Go to Step 9

Go to Step 11

Apply firm pressure to the brake pedal.
Use the J 39200 in order to measure the voltage between the stoplamp switch harness connector C1 terminal B and ground.

Is the voltage equal to or greater than the specified voltage?

10.0V

Go to Step 15

Go to Step 10

Inspect for proper adjustment of the stoplamp switch.

Is the stoplamp switch adjusted correctly?

Go to Step 17

Go to Step 18

Remove and inspect the fuse block STOPLAMP Fuse (15A).

Is the fuse OK?

Go to Step 12

Go to Step 13

Disconnect the stoplamp switch connector C1.
Use a J 39200 in order to measure the resistance between the stoplamp switch harness connector C1 terminal A and the fuse block terminal C6.

Is the resistance within the specified range?

0.0-2.0ohms

Go to Step 14

Go to Step 20

Disconnect the 24-way EBCM/EBTCM connector C1.
Use the J 39200 in order to measure the resistance between the 24-way EBCM/EBTCM connector C1 terminal B9 and ground.

Is continuity to ground present during this test?

Go to Step 19

Go to Step 21

Use the J 39200 in order to measure the voltage between the fuse block terminal C5 and ground.

Is the voltage equal to or greater than the specified voltage?

10V

Go to Step 23

Go to Power Distribution

Repair the open in CKT 17.

Is the repair complete?

Go to Diagnostic System Check

Replace all the terminal or the connectors that exhibit the following conditions: