Pinpoint Test 11: The Brake Warning Indicator Is Always On
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PINPOINT TEST 11: THE BRAKE WARNING INDICATOR IS ALWAYS ON - HYBRID
Normal Operation
The instrument cluster uses 3 basic messaged inputs to control the brake warning indicator. The first 2 are the parking brake warning indicator switch and brake fluid level switch. The third is for the electronic brake distribution (EBD), controlled by the anti-lock brake system (ABS). The parking brake warning indicator switch status is sent from the smart junction box (SJB) over the medium speed controller area network (MS-CAN) communication bus. The brake fluid level switch status is sent from the ABS module over the HS-CAN. The electronic brake distribution message is sent from the ABS module over the HS-CAN communication bus lines. The parking brake warning indicator switch is hardwired to the SJB through signal circuit (GY/L). The brake fluid level switch is hardwired to the SJB through signal circuit (GY/V).If the brake fluid level or parking brake status messages are missing or deemed invalid by the instrument cluster for more than 5 seconds, the instrument cluster sets DTC U0140 and defaults the brake warning indicator on. If the instrument cluster does not receive the ABS status message or the electronic brake distribution (EBD) message from the ABS module or the message is deemed invalid by the instrument cluster for greater than 5 seconds, the instrument cluster sets DTC U0129 and defaults the ABS warning indicator on.DTC B2479 (Park Brake Switch Circuit Short to Ground) - is an on-demand DTC that sets when the SJB detects a short to ground on the parking brake warning indicator switch input, circuit (GY/L) during the module self-test.
DTC C1125 (Brake Fluid Level Sensor Input Circuit Failure) - is a continuous and on-demand DTC that sets in the SJB if the SJB detects a short to ground on the brake fluid level input circuit (GY/V).
NOTE: If DTC U0140 is set in the instrument cluster, other symptoms may also be present such as tire pressure monitoring system (TPMS), instrument panel backlighting, and door ajar indication.
NOTE: Both the ABS warning indicator and the brake warning indicator illuminate if the input to turn on the brake warning indicator is received from the ABS module.
Possible Causes
- Wiring, terminals or connectors
- Parking brake warning indicator switch
- Brake fluid level switch (part of the brake fluid reservoir)
- ABS module
- SJB
- Instrument cluster
Diagnostic Procedure
CAUTION: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
Step 1-Step 5:
Step 6-Step 10:
Step 11:
