1994 PCED OBDI-A | SECTION 18A: Diesel Diagnosis — 7.3L DI Engine |
U1 DIAGNOSTIC TROUBLE CODE (DTC) 983
Diagnostic Trouble Code (DTC) 983 is set when the PCM cannot retrieve diagnostic information from the IDM via the EF circuit.
Possible causes:
- Open/ground short in EF circuit.
- Unpowered or damaged IDM.
- Unpowered or damaged PCM.
- Open IDM ground signal.
- Perform key on, engine off self-test again.
Is DTC 983 present?
| Yes | No |
|---|
| Only DTC 983 present. GO to U3. If DTC 955 and 956 are also present with DTC 983 GO to U7. If DTC 988 is also present with DTC 983 GO to V1. If DTC 955 is also present with DTC 983 GO to V1. If DTC 956 is also present with DTC 983 GO to T1. If DTC 549 is also present with DTC 983 GO to W1. | GO to U2. |
U2 MONITOR EF CIRCUIT UNDER SIMULATED ROAD SHOCK
- Enter Continuous Monitor Diagnostic Test Mode (DTM).
- Wiggle Circuit 818 (GY/W). Refer to schematic.
Is a fault indicated?
WARNING: RED-STRIPED WIRES CARRY 115V DC. SEVERE ELECTRICAL SHOCK MAY BE RECEIVED. DO NOT PIERCE.
CAUTION: Do not pierce engine electrical wires or damage to the harness may occur.
| Yes | No |
|---|
| SERVICE intermittent connection in Circuit 818 (GY/W). RERUN Scan Tool Diagnostic Test. | Unable to repeat concern. RETURN to symptom flow chart and continue. |
U3 CHECK CIRCUIT 818 (GY/W) FOR OPEN
- Key off.
- 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.
- Disconnect the injector driver module (IDM).
- Measure resistance between Pin 48 on breakout box and Circuit 818 (GY/W) at the IDM harness connector Pin Number 4.
Is resistance less than 5 ohms?
| Yes | No |
|---|
| GO to U4. | SERVICE open in Circuit 818 (GY/W). RERUN Scan Tool Diagnostic Test. |
U4 CHECK CIRCUIT 818 (GY/W) FOR SHORT
- Key off.
- Measure resistance between Pin 48 on the breakout box and chassis ground.
Is resistance greater than 10,000 ohms?
| Yes | No |
|---|
| GO to U5. | SERVICE ground short in Circuit 818 (GY/W). RERUN Scan Tool Diagnostic Test. |
U5 SIGNAL GROUND TEST
- Check signal ground.
- Install breakout box. Leave the PCM disconnected.
- Remove the IDM connector.
- Measure the resistance between the PCM Pin 91 to the IDM Pin 2.
Is there continuity?
| Yes | No |
|---|
| GO to U6. | REPAIR the signal ground circuit. |
U6 SUBSTITUTE PCM, RERUN QUICK TEST
- Key off.
- Reconnect IDM.
- Substitute known good PCM and reconnect.
- Enter key on, engine off self-test.
Is DTC 983 present?
| Yes | No |
|---|
| REPLACE IDM. RERUN Scan Tool Diagnostic Test. | REINSTALL old PCM. RERUN Scan Tool Diagnostic Test. |
U7 CHECK MAXI-FUSE NUMBER 8 FOR OPEN
- Key off.
- Check maxi-fuse No. 8.
Is fuse OK?
| Yes | No |
|---|
| GO to U8. | REPLACE fuse. GO to U3. |
U8 IDM POWER TEST
- Disconnect the IDM harness from the IDM.
- Turn key to the on position.
- Check for battery positive voltage at pin 14.
Is battery voltage present?
U9 IDM GROUND TEST
- Turn key to the off position.
- Check the IDM ground circuit by measuring the resistance from Pin 26 to the battery ground.
Is there continuity?
| Yes | No |
|---|
| REPLACE IDM. | REPAIR the ground circuit. |
U: Introduction