1994 PCED OBDI-A | SECTION 18A: Diesel Diagnosis — 7.3L DI Engine |
H1 DTC 147: EXCESSIVE BACK PRESSURE
DTC 147 indicates excessive exhaust back pressure was detected during continuous diagnostic monitoring.
Possible causes:
- Plugged sensor source
- Stuck butterfly
- Restricted exhaust
- Clear codes.
- Start engine and let idle for 2 minutes. The vehicle may need to be driven to load the engine.
- Shut off engine.
- Pull continuous DTCs.
Is DTC 147 present?
| Yes | No |
|---|
| CHECK for plugged sensor source, stuck butterfly or restricted exhaust. SERVICE as required. RERUN Quick Test. | SERVICE other DTCs as necessary. If none, testing complete. |
H2 DTC 145: EBP CIRCUIT LOW INPUT
DTC 145 indicates exhaust back pressure out of range low was detected during KOEO self-test or during continuous diagnostic monitoring.
Possible cause:
- Open EBP sensor circuit
- Biased sensor/PCM
- Short to SIGN RTN or PWR GND on EBP sensor circuit
- Key off.
- Disconnect EBP sensor.
- Disconnect PCM and check for damaged pins, etc.
- Connect breakout box. Leave PCM disconnected.
- Measure resistance between EBP circuit on sensor harness connector Pin C and Pin 30 on breakout box.
Is there continuity?
| Yes | No |
|---|
| GO to H3. | SERVICE open in circuit 553 (PL/LB). RERUN Scan Tool Diagnostic Test. |
H3 CHECK CIRCUIT 553 (PL/LB) FOR SHORT
- Disconnect EBP sensor.
- Disconnect PCM and check for damaged pins, etc.
- Connect breakout box. Leave PCM disconnected.
- Measure resistance between Pin 30 and Pins 91/51/76/77 and 103 on breakout box.
Is resistance greater than 10,000 ohms?
| Yes | No |
|---|
| GO to H4. | SERVICE short circuit in Circuit 553 (PL/LB). RERUN Scan Tool Diagnostic Test. |
H4 CHECK FOR SHORT ON PIN 30
- Disconnect EBP sensor.
- Connect breakout box and PCM.
- Measure resistance between Pins 30 and Pins 91/51/76/77 and 103.
Is resistance greater than 10,000 ohms?
| Yes | No |
|---|
| REPLACE EBP sensor. RERUN Scan Tool Diagnostic Test. | REPLACE PCM. REMOVE breakout box. RECONNECT EBP sensor. RERUN Scan Tool Diagnostic Test. |
H5 DTC 146: EBP CIRCUIT HIGH INPUT
DTC 146 indicates exhaust back pressure out of range high during KOEO self-test or during continuous diagnostic monitoring.
Possible causes:
- Biased sensor/PCM
- EBP circuit shorted to VREF
- Key off.
- Disconnect EBP sensor.
- Disconnect PCM and check for damaged pins, etc.
- Connect breakout box. Leave PCM disconnected.
- Measure resistance between Pin 30 and Pin 90.
Is resistance greater than 10,000 ohms?
| Yes | No |
|---|
| GO to H6. | SERVICE short circuit. RERUN Scan Tool Diagnostic Test. |
H6 CHECK FOR SHORT ON PIN 30
- Disconnect EBP sensor.
- Connect breakout box and PCM.
- Measure resistance between Pin 30 and Pin 90.
Is resistance greater than 10,000 ohms?
| Yes | No |
|---|
| REPLACE EBP sensor. RERUN Scan Tool Diagnostic Test. | REPLACE PCM. REMOVE breakout box. RECONNECT EBP sensor. |
H: Introduction