1994 PCED OBDI-A | SECTION 18A: Diesel Diagnosis — 7.3L DI Engine |
P1 DIAGNOSTIC TROUBLE CODE (DTC) 864
Diagnostic Trouble Code (DTC) 864 is set when the PCM detects a fault in the brake pressure applied switch circuit.
Possible causes:
- Open circuit.
- Operator does not apply more than 10 lbs pressure to brake pedal.
- Battery short in circuit.
- Open fuse.
- BPA switch worn or damaged.
- Perform Key On/Engine Running (KOER) Self-Test.
Is KOER DTC 864 still present?
| Yes | No |
|---|
| GO to P2. | SERVICE other DTCs as necessary. If none, testing complete. |
P2 CHECK FUSE FOR OPEN
- Check fuse F-5 15A in power network box.
Is fuse OK?
| Yes | No |
|---|
| GO to P3. | REPLACE fuse. RERUN Scan Tool Diagnostic Test. |
P3 CHECK CIRCUIT 298 FOR OPEN
- Key on, engine off.
- Measure voltage on Circuit 298 (P/O) at brake pressure switch.
Is B+ present?
| Yes | No |
|---|
| GO to P4. | SERVICE Circuit 298 (P/O) as necessary. RERUN Scan Tool Diagnostic Test. |
P4 MEASURE VOLTAGE ON BPA CIRCUIT
- Disconnect PCM. Check for damage or pushed-out pins. Service as necessary.
- Connect breakout box, reconnect PCM.
- Key on, engine off.
- Measure voltage between Test Pin 31 on the breakout box and chassis ground.
Is B+ present?
| Yes | No |
|---|
| GO to P5. | SERVICE open in Circuit 307 (BK/Y). |
P5 CHECK BPA SWITCH OPERATION
- Key on, engine off.
- Depress brake pedal firmly.
- Measure voltage between Test Pin 31 on the breakout box and chassis ground.
Is voltage less than 1 volt?
| Yes | No |
|---|
| BPA circuit tests OK. RETURN to symptom flow charts. | GO to P6. |
P6 CHECK FOR BATTERY SHORT ON BPA CIRCUIT
- Key off.
- Disconnect BPA switch.
- Key on, engine off.
- Measure voltage on Test Pin 31 on the breakout box.
Is B+ present?
| Yes | No |
|---|
| SERVICE battery short on Circuit 307 (BK/Y). RERUN Scan Tool Diagnostic Test. | BPA switch shorted. REPLACE switch. RERUN Scan Tool Diagnostic Test. |
P: Introduction