Circuit Description
The Stoplamp Switch is a normally open switch, when the brake pedal is depressed the EBCM will sense battery voltage. This allows the EBCM to determine the state of the brake lamps.
Conditions for Running the DTC
| • | The ignition switch is ON. |
| • | The DTC can be set after system initialization. |
Conditions for Setting the DTC
| • | EBCM detects battery voltage at all times. |
| • | EBCM never detects battery voltage from feed circuit. |
| • | Both brake lamps are faulty. |
Action Taken When the DTC Sets
If equipped, the following actions occur:
| • | The EBCM disables the ABS/TCS/VSES for the duration of the ignition cycle. |
| • | A malfunction DTC will set. |
| • | The ANTI-LOCK indicator turns ON. |
| • | The TRAC Off indicator turns ON. |
| • | The PCS indicator turns ON. |
| • | The Red BRAKE Warning indicator could turn on. |
Conditions for Clearing the DTC
| • | The condition for the DTC is no longer present and the DTC is cleared with a scan tool. |
| • | The electronic brake control module (EBCM) automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles. |
Diagnostic Aids
| • | 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. |
| • | Thoroughly inspect any circuitry that may be causing the complaint for the following conditions: |
| - | Backed out terminals |
| - | Improper mating |
| - | Broken locks |
| - | Improperly formed or damaged terminals |
| - | Poor terminal-to-wiring connections |
| - | Physical damage to the wiring harness |
| • | The following conditions may cause an intermittent malfunction: |
| - | A poor connection |
| - | Rubbed-through wire insulation |
| - | A broken wire inside the insulation |
| • | If an intermittent malfunction exists refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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This DTC detects an open stoplamp switch signal circuit from the stoplamp side of the splice to the EBCM.
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The EBCM sources 5 volts on the stoplamp switch signal circuit. This small voltage has a ground path through the stoplamp bulbs. This DTC sets if the path to ground is open.
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With the scan tool, Test for the current state of the brake lamp switch parameter.
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Test the stoplamp signal circuit for a short to voltage.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Antilock Brake System Schematics | |||
1 | Did you perform the ABS Diagnostic System Check? | Go to Step 2 | |
2 |
Does the Brake Switch Status parameter display Applied? | Go to Step 4 | Go to Step 3 |
Test the signal circuit of the stoplamp switch for an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 15 | Go to Step 11 | |
Press the brake pedal. Are all of the stoplamps OFF? | Go to Step 5 | Go to Step 7 | |
5 | Test the feed circuit of the stoplamps for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 15 | Go to Step 6 |
6 | Test the ground circuit of the stoplamps for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 15 | Go to Diagnostic Aids |
Does the Brake Switch Status parameter change state? | Go to Diagnostic Aids | Go to Step 8 | |
8 |
Did you find and correct the condition? | Go to Step 15 | Go to Step 9 |
9 |
Does the scan tool display Released? | Go to Step 11 | Go to Step 10 |
Test the stoplamp signal circuit for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 15 | Go to Step 12 | |
11 | Inspect for poor connections at the harness connector of the stoplamp switch. 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 15 | Go to Step 13 |
12 | 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 15 | Go to Step 14 |
13 | Replace the stoplamp switch. Refer to Stop Lamp Switch Replacement in Park Brake. Did you complete the repair? | Go to Step 15 | -- |
14 | Replace the EBCM. Refer to Electronic Brake Control Module Replacement . Did you complete the replacement? | Go to Step 15 | -- |
15 |
Does the DTC reset? | Go to Step 2 | System OK |
