Circuit Description
The Electronic Brake Control Module (EBCM) monitors brake pedal position through the stoplamp switch. The stoplamp switch is closed when the brake pedal is pressed and the stop lamp switch opens when the brake pedal is released. When the stoplamp switch is closed, the EBCM receives a voltage signal from the stoplamp switch. The stoplamp switch receives power from the STOP fuse.
Conditions for Setting the DTC
| • | DTC B3449 identifies an open in the stoplamp switch circuit. |
| • | DTC B3449 can be set anytime. |
Action Taken When the DTC Sets
The EBCM stores DTC B3449 turns ON the ABS indicator. If this DTC sets during the ABS stop, ABS will remain functional until the vehicle stops. Otherwise ABS is disabled.
Conditions for Clearing the DTC
The condition for the malfunction is no longer present and command the Clear DTC Information function with a scan tool.
Diagnostic Aids
Inspect the following list of items when diagnosing this part of the Antilock Brake System (ABS):
| • | Open STOP Fuse (possible short to ground in its circuitry) |
| • | Stoplamp switch out of adjustment |
| • | Faulty stoplamp switch (contacts open or closed at the time) |
| • | Open circuit between the stoplamp switch and the EBCM |
| • | Short to voltage between the stoplamp switch and the EBCM |
An intermittent malfunction is most likely caused by following conditions:
| • | A poor connection |
| • | A rubbed through wire insulation |
| • | A wire that is broken inside the insulation |
Inspect the following harness connectors for the following conditions:
| • | Backed-out terminals |
| • | Improper mating |
| • | Broken locks |
| • | Improperly formed or damaged terminals |
| • | Poor terminal to wiring connections or physical damage to the wiring harness before component replacement: |
| - | Junction block electrical connectors |
| - | Stoplamp switch electrical connector |
| - | EBCM electrical connector |
Test Description
The number(s) below refer to the step number(s) on the diagnostic table.
-
This step checks the Stop Lamp Switch status with the switch OFF.
-
This step checks the Stop Lamp Switch status with the switch applied.
-
This step ensures proper adjustment of the Stop Lamp Switch.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform A Diagnostic System Check - ABS? | -- | Go to Step 2 | |
Does the scan tool display Released? | -- | Go to Step 3 | Go to Step 4 | |
Press the brake pedal while observing the Brake Switch parameter. Does the Brake Switch parameter change state? | -- | Go to Diagnostic Aids | Go to Step 4 | |
Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 5 | |
5 |
Does the scan tool display Released? | -- | Go to Step 8 | Go to Step 6 |
6 | Test the Brake Switch circuit for an open or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 7 |
7 | Inspect for poor connections at the harness connector of the EBCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 9 |
8 | Inspect for poor connections at the harness connector of the EBCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 10 |
9 | Replace the Brake Modulator Assembly. Refer to Brake Pressure Modulator Valve Assembly Replacement . Did you complete the replacement? | -- | Go to Step 11 | -- |
10 | Replace the Stop Lamp Switch. Refer to Stop Lamp Switch Replacement . Did you complete the replacement? | -- | Go to Step 11 | -- |
11 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
