Cylinder Identification (CID)

1994 PCED OBDI-A

SECTION 18A: Diesel Diagnosis — 7.3L DI Engine

V: Cylinder Identification (CID)

V: Introduction

V1 DIAGNOSTIC TROUBLE CODES (DTCs) 955, 915, 916, 983, 988

These DTCs indicate that the PCM has detected a concern on the CID line.

Possible causes:

Damaged IDM.
Open or grounded circuit.

Is DTC 983 retrieved alone?

Yes	No
GO to U1.	If DTC 955 retrieved with 983, GO to V2. If DTC 915 retrieved continuous code, GO to V15. If DTC 916 retrieved continuous code, GO to V15. If DTC 988 retrieved alone, REPLACE IDM. If DTC 955 retrieved alone, GO to V2.

V2 CYLINDER IDENTIFICATION LINE TEST

Diagnostic trouble codes 955 or DTC 983 and 955 retrieved together indicates there is a short high, short low or open on the CI line.

Connect breakout box between harness and PCM.
Key on, engine off.
Measure voltage between Pin 96 and ground.

Is 0.6 ± 0.1 volt present?

Yes	No
GO to V3.	GO to V4.

V3 PERFORM AN OUTPUT STATE CHECK

With a Super STAR II tester connected follow the output state test procedure as described in Scan Tool Diagnostic Procedures Test Step 3.1.
Connect volt ohmmeter between Pin 96 and ground.

Does volt ohmmeter toggle between 0.6 ± 0.1 volt and battery voltage?

Yes	No
GO to V15.	REPLACE PCM. GO to V13.

V4 CHECK VOLTAGE ON 817 Y/LB

Check voltage on Pin 96.
Key on, engine off.
Measure voltage between Pin 96 and ground.

Is less than 0.5 volt present?

Yes	No
GO to V6.	GO to V5.

V5 CHECK BATTERY VOLTAGE ON PIN 96

Key on, engine off.
Measure voltage between Pin 96 and ground.

Is battery voltage present?

Yes	No
GO to V7.	GO to V6.

V6 CIRCUIT 817 CONTINUITY CHECK

To check continuity on Circuit 817 disconnect PCM from breakout box.
Disconnect IDM from harness.
Key off.
Check continuity between Pin 96 and Pin 16 on IDM.

Is there continuity?

Yes	No
GO to V9.	REPAIR open in Circuit 817 (Y/LB). RERUN circuit test.

V7 CHECK CID CIRCUIT FOR SHORT TO BATTERY VOLTAGE

Key on, engine off.
Check from Pin 96 and from IDM Pin 16 to ground.

Is battery voltage present?

Yes	No
REPAIR short to battery voltage. RETEST system.	GO to V8.

V8 HARNESS INSPECTION

Inspect harness at PCM Pin number 96.

Is there any damage or corrosion?

Yes	No
REPAIR damage to connector. RERUN test.	REPLACE PCM. GO to V13.

V9 CHECK CID CIRCUIT FOR SHORT TO GROUND

Key off.
Check from Pin 96 and from IDM Pin 16 to ground.

Is resistance less than 1000 ohms?

Yes	No
REPAIR ground short in Circuit 817 (Y/LB). RETEST system.	GO to V10.

V10 CIRCUIT INSPECTION TEST

Inspect harness and IDM connector at Pin 16 for damaged or corroded pins.

Is there any damage or corrosion?

Yes	No
REPAIR damage to connector. RERUN test.	GO to V11.

V11 RERUN KOEO TEST WITH NEW IDM MODULE

Install new IDM.
Remove breakout box and reconnect harness to PCM.
Perform KOEO test.

Does system display pass code?

Yes	No
System OK.	GO to V12.

V12 RETEST ORIGINAL IDM

Reinstall the original IDM.
Perform KOEO test.

Does system function properly?

Yes	No
Carefully RECHECK IDM pins and harness connector for corrosion or damage. REPAIR or REPLACE as necessary.	Original IDM damaged. REPLACE IDM.

V13 RUN KOEO TEST WITH NEW PCM

Install new PCM.
Perform KOEO test.

Does system function properly?

Yes	No
GO to V14.	Carefully RECHECK PCM harness and connector pins for open or short condition. REPAIR as necessary.

V14 RETEST ORIGINAL PCM

Install original PCM.
Perform KOEO test.

Does system function properly?

Yes	No
Carefully CHECK PCM pins and connector for corrosion or damage. REPAIR as necessary.	PCM damaged. REPLACE PCM.

V15 INTERMITTENT SHORT OR OPEN ON CID CIRCUIT

Clear all DTC codes.
Key on, engine running at idle.
Grasp the harness with an insulated tool.

WARNING: THERE ARE 115 VOLTS PRESENT ON THE CID CIRCUIT AND PERSONAL INJURY MAY RESULT IF PROPER PROCEDURES ARE NOT FOLLOWED.

Shake the harness.

Does the engine stall or stumble?

Yes	No
CORRECT intermittent short or open on faulty circuit.	RUN KOEO test. GO to V16.

V16 CHECK FOR PRESENCE OF CODES 915 OR 916

Perform KOEO test.

Is DTC 915 or 916 retrieved?

Yes	No
Carefully INSPECT harness and connector pins at PCM and IDM for corrosion or damage. REPAIR as necessary.	System tests OK.