1994 PCED OBDI-A | SECTION 18A: Diesel Diagnosis — 7.3L DI Engine |
X1 DIAGNOSTIC TROUBLE CODE 546
DTC 546 is set when an open or ground short on the IPR circuit is detected by the PCM.
Check power to IPR regulator.
- Remove IPR harness connector.
- Turn ignition key on.
- Measure voltage at point A in the harness connector.
Is 12v ±1.5 volts present?
| Yes | No |
|---|
| GO to X2. | SERVICE open Circuit 361 (R). RERUN test. |
X2 IPR HARNESS CONTROL CIRCUIT — CONTINUITY
- Install breakout box. Leave the PCM disconnected.
- Measure continuity from PCM Pin 83 to Point B in the IPR regulator harness connector.
Is there continuity?
| Yes | No |
|---|
| GO to X3. | SERVICE open Circuit 552 (Y/R). RERUN test. |
X3 IPR HARNESS CONTROL CIRCUIT — SHORT TO GROUND
- Install breakout box. Leave the PCM disconnected and leave IPR disconnected.
- Measure continuity from PCM Pin 83 to ground.
Is there continuity?
| Yes | No |
|---|
| REPAIR short to ground. | GO to X4. |
X4 CHECK IPR COIL RESISTANCE
- Measure resistance of IPR coil.
Is resistance 8 to 16 ohms?
| Yes | No |
|---|
| REPLACE PCM. | REPLACE IPR. RERUN test. |
X5 DTC: 155 EXCESSIVE INJECTOR CONTROL PRESSURE
DTC 155 indicates excessive injector control pressure was detected during continuous diagnostic monitoring.
Possible causes:
- Intermittent IPR control circuit short to ground.
- Stuck IPR.
- Check for intermittent-IPR control circuit to ground.
- Install breakout box. Leave the PCM disconnected and leave IPR disconnected.
- Measure continuity from PCM Pin 83 to ground.
- Wiggle IPR circuit connectors and wires to attempt to induce short to ground.
Is there continuity?
| Yes | No |
|---|
| REPAIR short to ground. | REPLACE IPR. RETEST. |
X6 DTC 841: ICP STEADY STATE ERROR
DTC 841 indicates ICP pressure above or below desired pressure (continuous mode) or the ICP system could not maintain commanded pressure during KOER.
Possible causes:
- Sticking IPR valve.
- Worn or leaking injectors.
- Injector O-ring leak.
- Worn or leaking high pressure pump.
- If engine rpm is unstable, unplug ICP sensor and monitor rpm.
Does engine rpm remain unstable?
X: Introduction