1994 PCED OBDI-A | SECTION 18A: Diesel Diagnosis — 7.3L DI Engine |
Q1 DIAGNOSTIC TROUBLE CODE (DTC) 863
Diagnostic Trouble Code (DTC) 863 is set when the PCM detects a fault in the parking brake applied switch circuit.
Possible causes:
- Ground short in circuit.
- Battery short in circuit.
- Parking brake applied switch worn or damaged.
- Perform Key On/Engine Running (KOER) Self-Test.
Is KOER DTC 863 still present?
| Yes | No |
|---|
| GO to Q2. | SERVICE other DTCs as necessary. If none, testing complete. |
Q2 RABS LIGHT ON
Is the rear anti-lock brake system (RABS) warning light on?
| Yes | No |
|---|
| REPAIR rear anti-lock brake system according to Section 06-09 of the F-Series Body/Chassis Service Manual. | GO to Q3. |
Q3 BRAKE WARNING LIGHT PRESENT
Does the brake warning light stay on?
| Yes | No |
|---|
| GO to Section 06-00 of the F-Series Body/Chassis Service Manual for diagnostic service. | GO to Q4. |
Q4 CHECK PARKING BRAKE SWITCH OPERATION (BRAKE APPLIED)
- Disconnect PCM. Check for damaged or pushed-out pins. Service as necessary.
- Connect breakout box. Leave PCM disconnected.
- Key on, engine off.
- Apply parking brake.
- Measure voltage between Test Pin 4 and chassis ground.
Is voltage less than 1 volt?
Q5 CHECK PARKING BRAKE SWITCH OPERATION (BRAKE RELEASED)
- Key on, engine off.
- Release parking brake.
- Measure voltage between Test Pin 4 and chassis ground.
Is B+ present?
| Yes | No |
|---|
| PBA circuit checks OK. RETURN to symptom flow charts. | GO to Q6. |
Q6 CHECK CIRCUIT 977 (P/W) FOR SHORT
- Key off.
- Disconnect parking brake switch.
- Measure resistance between Test Pin 4 and chassis ground.
Is resistance greater than 10,000 ohms?
| Yes | No |
|---|
| REPLACE PBA switch. RERUN Scan Tool Diagnostic Test. | SERVICE ground short in Circuit 977 (P/W). RERUN Scan Tool Diagnostic Test. |
Q7 CHECK CIRCUIT 977 (P/W) FOR BATTERY SHORT
- Key off.
- Disconnect parking brake switch.
- Measure voltage between Test Pin 4 on the breakout box and chassis ground.
Is voltage less than 1 volt?
| Yes | No |
|---|
| GO to Q8. | SERVICE battery short in Circuit 977 (P/W). RERUN Scan Tool Diagnostic Test. |
Q8 CHECK CIRCUIT 977 (P/W) FOR OPEN
- Measure resistance between Pin 4 on the breakout box and Circuit 977 (P/W) at the PBA switch connector.
Is resistance less than 5 ohms?
| Yes | No |
|---|
| REPLACE PBA switch. RERUN Scan Tool Diagnostic Test. | SERVICE open in Circuit 977 (P/W). RERUN Scan Tool Diagnostic Test. |
Q: Introduction