Normal Operation

The brake warning light is used to indicate low fluid level (base brake system concern) or a parking brake that is not fully released. The instrument cluster is hardwired to the parking brake switch through circuit (GY/L) for parking brake status. The instrument cluster is hardwired to the anti-lock brake system (ABS) module through the electronic brake distribution (EBD) line, circuit (G/V), for brake fluid level concerns. When the parking brake is applied, the instrument cluster receives a ground and turns on the brake warning indicator. When brake fluid is low or the ABS module detects a base brake system concern, the ABS module sends the instrument cluster a signal through the EBD line and the instrument cluster illuminates the brake warning indicator.

DTC C1226 (ABS Warning Lamp Output Circuit Short to Ground) - sets if the instrument cluster detects a short to ground on circuit (G/V) during the instrument cluster initiation and bulb check.

This pinpoint test is intended to diagnose the following:

Wiring, terminals or connectors
Brake fluid level switch
Parking brake switch
ABS module
Instrument cluster
CAUTION:
- Use the correct probe adapters) when making measurements. Failure to use the correct probe adapters) may damage the connector.

BRAKE WARNING INDICATOR PINPOINT TEST 16

PINPOINT TEST 16		THE BRAKE WARNING INDICATOR IS NEVER ON
STEP	INSPECTION		ACTION
1	CARRY OUT THE INSTRUMENT CLUSTER INDICATOR LAMP CONTROL ACTIVE COMMAND USING THE SCAN TOOL Key in ON position. Enter the following diagnostic mode on the scan tool: Instrument Cluster DataLogger Select the instrument cluster brake warning indicator (BRK_LAMP) active command. Command the brake warning indicator on. Observe the brake warning indicator. Does the brake warning indicator illuminate when commanded on?	Yes	Go to next step.
1		No	Go to step 11.
2	RETRIEVE THE RECORDED DTCs FROM BOTH THE CONTINUOUS AND ON-DEMAND INSTRUMENT CLUSTER SELF-TESTS Use the recorded instrument cluster DTCs from the continuous and on-demand self-tests. Are any DTCs present?	Yes	For DTC C1226, go to step 8. For all other instrument cluster DTCs, see INSTRUMENT CLUSTER DIAGNOSTIC TROUBLE CODE (DTC) INDEX .
2		No	If the brake warning indicator does not operate with the parking brake, go to next step. If the brake warning indicator does not operate with low brake fluid level, go to step 6.
3	CHECK THE PARKING BRAKE INPUT Key in OFF position. Disconnect: Parking Brake Switch connector 0918-201. Connect a fused (10A) jumper wire between the parking brake switch 0918-201 pin 1, circuit (GY/L), harness side and the parking brake switch 0918-201 pin 2, circuit (B/L), harness side. Key in ON position. Does the brake warning indicator illuminate?	Yes	INSTALL a new parking brake switch. TEST the system for normal operation.
3		No	REMOVE the jumper wire. Go to next step.
4	CHECK CIRCUIT (B/L) FOR AN OPEN Key in OFF position. Measure the resistance between the parking brake switch 0918-201 pin 2, circuit (B/L), harness side and ground. Is the resistance less than 5 ohms?	Yes	Go to next step.
4		No	REPAIR the circuit. TEST the system for normal operation.
5	CHECK THE CIRCUIT (GY/L) FOR AN OPEN Disconnect: Instrument Cluster connector 0922-101. Measure the resistance between the instrument cluster 0922-101 pin 20, circuit (GY/L), harness side and the parking brake switch 0918-201 pin 1, circuit (GY/L), harness side. Is the resistance less than 5 ohms?	Yes	Go to step 11.
5		No	REPAIR the circuit. TEST the system for normal operation.
6	CHECK THE BRAKE FLUID LEVEL SWITCH INPUT Key in OFF position. Disconnect: Brake Fluid Level Switch connector 0413-106. Key in ON position. Does the brake warning indicator illuminate?	Yes	Go to next step.
6		No	Go to step 10.
7	CHECK CIRCUIT (B/Y) FOR AN OPEN Key in OFF position. Measure the resistance between the brake fluid level switch 0413-106 pin 1, circuit (B/Y), harness side and ground. Is the resistance less than 5 ohms?	Yes	INSTALL a new brake fluid level switch. TEST the system for normal operation.
7		No	REPAIR the circuit. TEST the system for normal operation.
8	CHECK THE ABS MODULE OPERATION Key in OFF position. Disconnect: ABS Module connector 0413-102. Connect: Brake Fluid Level Switch connector 0413-106. Key in ON position. Does the brake warning indicator stay illuminated after prove-out?	Yes	Go to step 10.
8		No	Go to next step.
9	CHECK CIRCUIT (G/V) FOR A SHORT TO GROUND Key in OFF position. Disconnect: Instrument Cluster connector 0922-101. Measure the resistance between the instrument cluster 0922-101 pin 16, circuit (G/V), harness side and ground. Is the resistance greater than 10,000 ohms?	Yes	Go to step 11.
9		No	REPAIR the circuit. TEST the system for normal operation.
10	CHECK FOR CORRECT ABS MODULE OPERATION Disconnect the ABS module connector. Check for: corrosion damaged pins pushed-out pins Connect the ABS module connector and make sure it seats correctly. Operate the system and verify the concern is still present. Is the concern still present?	Yes	INSTALL a new ABS module. See ANTI-LOCK BRAKE SYSTEM (ABS) MODULE . TEST the system for normal operation.
10		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.
11	CHECK FOR CORRECT INSTRUMENT CLUSTER OPERATION Disconnect all the instrument cluster connectors. Check for: corrosion damaged pins pushed-out pins Connect all the instrument cluster connectors and make sure they seat correctly. Operate the system and verify the concern is still present. Is the concern still present?	Yes	INSTALL a new instrument cluster. See INSTRUMENT CLUSTER . CLEAR the DTCs. REPEAT the self-test.
11		No	The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.