Circuit Description
This circuit detects an open stoplamp/BTSI switch in the non-ABS mode. The EBTCM looks for a deceleration rate that indicates braking action and requires several repeats of this detection method in order to verify this assumption. In each case, the TCS will not be available since the EBTCM detects no stoplamp/BTSI switch voltage.
Conditions for Setting the DTC
| • | The stoplamp/BTSI switch remains open for 3 deceleration cycles. |
| • | The DTC is set in the current or previous ignition cycle. |
Action Taken When the DTC Sets
| • | A malfunction DTC is stored. |
| • | The TCS is disabled. |
| • | The TRACTION CONTROL indicator is turned ON. |
| • | The ABS remains functional. |
Conditions for Clearing the DTC
| • | The condition for DTC is no longer present and you used scan tool Clear DTCs function. |
| • | The condition for DTC is no longer present and you used the On-Board Clear DTCs function. |
| • | The EBTCM does not detect the DTC in 50 drive cycles. |
Diagnostic Aids
| • | If any wheel speed sensor DTCs are present, diagnose them first. Refer to Diagnostic Trouble Code (DTC) List . |
| • | 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 a poor connection, 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 DTC may be caused by one of the following: |
| - | An open stoplamp/BTSI switch. |
| - | An open rear junction block STOP LP Fuse. |
| - | The stoplamp/BTSI switch is misadjusted. |
| - | Erratic wheel speeds. |
| - | Circuit has a wiring problem, terminal corrosion, or poor connections. |
Test Description
The numbers below refer to step numbers on the diagnostic table.
-
Checks if the stoplamp/BTSI switch and power distribution are functional.
-
Checks for voltage at EBTCM.
-
Checks the stoplamp/BTSI switch.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check? | -- | Go to Step 2 | Go to Diagnostic System Check |
2 | Are any wheel speed sensor DTCs present? | -- | Go to Step 3 | |
Press the brake pedal. Do the brake lights come on? | -- | Go to Step 4 | Go to Step 7 | |
Is the voltage within the specified range? | 10.5-17 V | Go to Step 5 | Go to Step 6 | |
5 | Replace the EBTCM. Refer to Electronic Brake Control Module Replacement . Did you complete the repair? | -- | Go to Diagnostic System Check | -- |
6 | Repair the open in CKT 17. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Diagnostic System Check | -- |
7 | Check the rear junction block STOP LP Fuse. Is the fuse good? | -- | Go to Step 8 | Go to Step 12 |
8 |
Is the voltage within the specified range? | Battery Voltage | Go to Step 10 | Go to Step 9 |
9 | Repair the open in CKT 1640. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Diagnostic System Check | -- |
Connect a fused jumper wire between the stoplamp/BTSI switch harness connector C1 terminals A and B. Do the brake lamps come on? | -- | Go to Step 11 | Go to Step 6 | |
11 | Adjust or repair the stoplamp/BTSI switch as necessary. Refer to Stop Lamp Switch Replacement or Stop Lamp Switch Adjustment in Hydraulic Brakes. Did you complete the repair? | -- | Go to Diagnostic System Check | -- |
12 |
Is the fuse good? | -- | Go to Step 14 | Go to Step 13 |
13 | Repair short to ground in CKT 1640. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Diagnostic System Check | -- |
14 |
Is the fuse good? | -- | Go to Diagnostic System Check | Go to Step 15 |
15 |
Is the fuse good? | -- | Go to Step 5 | Go to Step 16 |
16 | Repair short to ground in CKT 17. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | -- | Go to Diagnostic System Check | -- |
