Circuit Description
The body control module (BCM) applies a ground through the brake sensor reference low circuit to the brake pedal position (BPP) sensor. The BCM supplies a 5-volt reference through the brake sensor reference voltage circuit to the brake position sensor. When the brake pedal is being applied, the BPP sensor then sends a variable voltage signal through the brake sensor signal circuit to the BCM.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC C0870 Device Voltage Reference Output Circuit
Conditions for Running the DTC
The battery voltage must be between 9-16 volts.
Conditions for Setting the DTC
C0870 03
A short to ground or an open in the BPP sensor voltage reference circuit is present.
C0870 07
A short battery positive voltage in the BPP sensor voltage reference circuit is present.
Action Taken When the DTC Sets
The stop lamps will not function correctly.
Conditions for Clearing the DTC
| • | The DTC will clear on current status after the condition for setting the fault is corrected. |
| • | A history DTC will clear after 100 consecutive ignition cycles without a fault present. |
| • | A history or current DTC can be cleared using a scan tool. |
Diagnostic Aids
Perform a visual inspection for loose or poor connections at all related components. Refer to Testing for Intermittent Conditions and Poor Connections .
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Exterior Lights Schematics Connector End View Reference: Master Electrical Component List | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
2 |
Does the scan tool display a change in the voltage? | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 3 |
3 | Is DTC C0870 03 present? | Go to Step 6 | Go to Step 4 |
4 |
Does the test light illuminate? | Go to Step 5 | Go to Step 10 |
5 | Test for a short to battery positive voltage in the brake sensor voltage reference circuit. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 12 | Go to Step 7 |
6 | Test for a short to ground or an open on the brake sensor reference voltage circuit. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 12 | Go to Step 7 |
7 | Inspect for a high resistance or a poor connection at the harness connector of the brake position sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 12 | Go to Step 8 |
8 |
Important: After replacing the brake pedal sensor, perform the calibration procedure. Refer to Brake Pedal Position Sensor Calibration . Replace the brake pedal position (BPP) sensor. Refer to Brake Pedal Position Sensor Replacement . Did you complete the replacement? | Go to Step 9 | -- |
9 |
Does DTC C0870 reset? | Go to Step 10 | Go to Step 12 |
10 | Inspect for a high resistance or a poor connection at the harness connector of the BCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 12 | Go to Step 11 |
11 | Replace the BCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 12 | -- |
12 |
Does the DTC reset? | Go to Step 2 | System OK |
