1996 PCED OBDI | SECTION 18: Diesel Diagnosis — 7.3L DI Engine |
M1 DIAGNOSTIC TROUBLE CODE (DTC) 0475: CHECK FOR GROUND IN CIRCUIT 574 (BK/PK). DTC 0475 INDICATES THAT A CIRCUIT FAILURE HAS OCCURRED IN THE EBP CONTROL SOLENOID CIRCUIT
- Possible causes:
- Shorted to power
- Open/grounded circuit
- Damaged solenoid
- Damaged PCM
- Disconnect EPR harness.
- Key off.
- Measure resistance from Pin A to ground.
Is the resistance less than 5 ohms?
Yes | No |
GO to M2. | SERVICE open in Circuit 574 (BK/PK). RERUN Scan Tool Diagnostic Test. |
M2 CHECK EPR COIL
- Measure resistance across EPR coil contacts A and B.
Is the coil resistance between 2.5 ohms and 12 ohms?
Yes | No |
GO to M3. | REPLACE regulator. RERUN Scan Tool Diagnostic Test. |
M3 CHECK FOR SHORT TO POWER IN CIRCUIT 318 (GY/R).
- Disconnect PCM. Inspect terminals for damage or corrosion, service as required.
- Measure voltage from Pin B to ground.
Is B+ present?
Yes | No |
SERVICE short to power in Circuit 318 (GY/R). RERUN Scan Tool Diagnostic Test. | GO to M4. |
M4 CHECK CIRCUIT 318 (GY/R) FOR SHORT TO GROUND
- Disconnect PCM.
- EPR disconnected.
- Measure resistance from Pin B to ground.
Is the resistance greater than 10,000 ohms?
Yes | No |
GO to M5. | SERVICE short to ground in Circuit 318 (GY/R). RERUN Scan Tool Diagnostic Test. |
M5 PERFORM OUTPUT STATE CHECK
- Disconnect EPR.
- Attach NGS Tester.
- Key on, engine off.
- Measure voltage between EBP connector harness side pin B and chassis ground.
- Run KOEO Output State Test on NGS Tester.
Does voltage toggle between 12v and 0v?
Yes | No |
REASSEMBLE system. RERUN standard KOEO and KOER tests. If codes still present, REPLACE PCM. | GO to M6. |
M6 CHECK FOR OPEN IN CIRCUIT 318 (GY/R)
- PCM disconnected.
- EPR disconnected.
- Install breakout box.
- Measure resistance from Pin B to Test Pin 42.
Is resistance less than 5 ohms?
Yes | No |
REASSEMBLE system. RERUN standard KOEO and KOER tests. If codes still present, REPLACE PCM. | SERVICE open in Circuit 318 (GY/R). RERUN Scan Tool Diagnostic Test. |
M7 KOER DIAGNOSTIC TROUBLE CODE (DTC) 0476
- DTC 0476 indicates an exhaust back pressure control valve performance malfunction was detected during KOER On-Demand Self Test.
- Possible causes:
- Stuck or damaged butterfly
- Misadjusted or damaged linkage
- Restricted exhaust
- Exhaust leaks
- Faulty PCM
- EPR valve
- EBP sensor
- If KOEO EBP faults are present, repair them before continuing.
- Visually inspect butterfly tang (refer to the exhaust back pressure regulator tang position illustration in the Performance Diagnostic Procedures section Step 13 for tang orientation).
Is tang in the open position?
Yes | No |
GO to M8. | REPAIR condition causing valve to be stuck closed. |
M8 EXHAUST RESTRICTION CHECK
- NGS Tester installed.
- Select EBP PID from the PID/DATA monitor menu on NGS Tester.
- Engine running.
- Accelerate engine to WOT and hold for 30 seconds.
Is EBP below 28 psi?
Yes | No |
GO to M9. | REPAIR restricted exhaust condition. CLEAR DTC and RETEST. |
M9 EBP SENSOR CHECK
- NGS Tester installed.
- Select EBP PID from the PID/DATA monitor menu on NGS Tester.
- Engine running.
- Record EBP valve.
- Accelerate engine several times.
Does EBP increase at least 4 psi with acceleration?
Yes | No |
M10. | REPLACE EBP sensor. RETEST system. |
M10 INSPECT FOR EXHAUST LEAKS
- Inspect turbo pipe, crossover pipes and exhaust manifolds for leaks.
Are exhaust leaks present?
Yes | No |
REPAIR exhaust leak. CLEAR DTCs and RETEST. | GO to M11. |
M11 EBP CHECK DURING KOER
- Key off.
- Disconnect EBP sensor connector.
- Inspect for damaged or pushed out pins, loose wires or corrosion. Service as necessary.
- Install ICP/EBP Adapter Cable D94T-50-A or equivalent between EBP sensor and vehicle harness.
- Measure voltage between signal circuit and signal ground on ICP/EBP Adapter Cable D94T-50-A or equivalent.
- Perform KOER On-Demand Self Test.
Does voltage increase 2.0v ± .5 and then decrease as the test ends?
Yes | No |
REPLACE PCM. CLEAR DTCs and RETEST. | GO to M12. |
M12 EPR VISUAL INSPECTION
- Observe EPR valve linkage while performing KOER On-Demand Self Test.
Does the linkage move during the test?
Yes | No |
CHECK EPR linkage adjustment. REFER to Section 03-04E of the Powertrain, Drivetrain Service Manual for adjustment procedure. RETEST system. | REPLACE EPR valve. CLEAR DTCs and RETEST. |