1994 PCED OBDI-A | SECTION 18A: Diesel Diagnosis — 7.3L DI Engine |
E1 DIAGNOSTIC TROUBLE CODE (DTC) 123:
ATTEMPT TO GENERATE DTC 122
DTC 123 indicates the accelerator pedal (AP) sensor signal is greater than the Self-Test maximum value.
Possible causes are:
- Damaged accelerator pedal assembly.
- AP sensor may not be seated properly (tightened down).
- Damaged AP sensor.
- Short to power in harness.
- Damaged powertrain control module (PCM).
- Key off.
- Disconnect AP sensor. Inspect for damaged or pushed-out pins, corrosion, loose wires, etc. Service as necessary.
- Rerun Key On Engine Off Self-Test.
Is DTC 122 present (ignore all other DTCs)?
E2 CHECK VREF CIRCUIT VOLTAGE
- Key off.
- AP sensor disconnected.
- Key on, engine off.
- Measure voltage between VREF circuit and SIG RTN circuit at the AP sensor vehicle harness connector, top terminal to bottom terminal.
Is voltage between 4.5 and 5.5 volts?
| Yes | No |
|---|
| REPLACE Accelerator Pedal and Sensor Assembly. RERUN Scan Tool Diagnostic Test. | Key off. RECONNECT all components. GO to Pinpoint Test Step B1. |
E3 CHECK AP CIRCUIT FOR SHORTS TO POWER
- Key off.
- AP sensor disconnected.
- Disconnect powertrain control module (PCM). Inspect for damaged or pushed-out pins, corrosion, loose wires, etc. Service as necessary.
- Install breakout box, leave PCM disconnected.
- Measure resistance between Test Pin 89 and Test Pins 90 and 55 at the breakout box.
Is each resistance greater than 10,000 ohms?
| Yes | No |
|---|
| REPLACE PCM.REMOVE breakout box. RECONNECT AP sensor. RERUN Scan Tool Diagnostic Test. | SERVICE short circuit. REMOVE breakout box. RECONNECT all components. RERUN Scan Tool Diagnostic Test. |
E4 DIAGNOSTIC TROUBLE CODE (DTC) 122:
ATTEMPT TO GENERATE DTC 123
DTC 122 indicates the accelerator pedal position sensor signal is less than the self-test minimum value.
Possible causes:
- AP sensor may not be seated properly (tightened down).
- Damaged AP sensor.
- Open harness.
- Grounded harness.
- Damaged powertrain control module (PCM).
- Key off.
- Disconnect AP sensor. Inspect for damaged or pushed out pins, corrosion, loose wires, etc. Service as necessary.
- Jumper VREF circuit to AP circuit at AP sensor vehicle harness connector.
- Run Key On Engine Off Self-Test.
Is DTC 123 present (ignore all other DTCs)?
| Yes | No |
|---|
| REPLACE Accelerator Pedal and Sensor Assembly. REMOVE jumper. RERUN Scan Tool Diagnostic Test. | REMOVE jumper. GO to E5. |
E5 CHECK VREF CIRCUIT VOLTAGE
- Key off.
- AP sensor disconnected.
- Key on, engine off.
- Measure voltage between VREF circuit and SIG RTN circuit at the AP sensor vehicle harness connector, top terminal to bottom terminal.
Is voltage between 4.5 and 5.5 volts?
| Yes | No |
|---|
| GO to E6. | Key off. RECONNECT all components. GO to Pinpoint Test Step B1. |
E6 CHECK AP CIRCUIT CONTINUITY
- Key off.
- AP sensor disconnected.
- Disconnect powertrain control module (PCM). Inspect for damaged or pushed-out pins, corrosion, loose wires, etc. Service as necessary.
- Install breakout box, leave PCM disconnected.
- Measure resistance between AP circuit at the AP sensor vehicle harness connector and Test Pin 89 at the breakout box, to the middle terminal.
Is the resistance less than 5 ohms?
| Yes | No |
|---|
| GO to E7. | SERVICE open circuit. REMOVE breakout box. RECONNECT all components. RERUN Scan Tool Diagnostic Test. |
E7 CHECK AP CIRCUIT FOR SHORTS TO GROUND
- Key off.
- AP sensor disconnected.
- Disconnect powertrain control module (PCM). Inspect for damaged or pushed-out pins, corrosion, loose wires, etc. Service as necessary.
- Install breakout box, leave PCM disconnected.
- Measure resistance between Test Pin 89 and Test Pins 51, 76, 77, 91 and 103 at the breakout box.
Is each resistance greater than 10,000 ohms?
| Yes | No |
|---|
| REPLACE PCM. REMOVE breakout box. RECONNECT all components. RERUN Scan Tool Diagnostic Test. | SERVICE short circuit. REMOVE breakout box. RECONNECT all components. RERUN Scan Tool Diagnostic Test. |
E: Introduction