Transmission Control Switch (TCS)/Transmission Control Indicator Lamp (TCIL)

1996 PCED OBDI

SECTION 18: Diesel Diagnosis — 7.3L DI Engine

AK: Transmission Control Switch (TCS)/Transmission Control Indicator Lamp (TCIL)

AK: Introduction

AK1 DIAGNOSTIC TROUBLE CODE (DTC) 1780: TCS NOT CYCLED DURING KOER SWITCH TEST

Possible causes:

TCS failure
TCS circuitry
TCS operation omitted during KOER
PCM failure

Key on.
Plug in NGS Tester.
Display NGS Tester PID "CPP."
Cycle TCS.

Does PID show OFF (12v) when TCS is pressed on and ON (0v) when TCS is released?

Yes	No
TCS is OK. CHECK TCIL. GO to AK15.	GO to AK2.

AK2 CHECK "CCP" FOR OFF ONLY

Key on.
Cycle TCS.

Does PID "CCP" show OFF (12v) only?

Yes	No
GO to AK3.	GO to AK5.

AK3 CHECK FOR TCS FAILED CLOSED

Key on, engine off.
Unplug TCS connector.

Does PID "CPP" go to ON (0v)?

Yes	No
REPLACE TCS/TCIL. CONFIRM fix with NGS Tester PID "CPP."	GO to AK4.

AK4 CHECK FOR SHORT TO B+ IN CIRCUIT 224 (T/W)

(TCS connector unplugged)
Key off.
Unplug PCM.
Key on.
Check voltage between TCS connector contact for Circuit 224 (T/W) and chassis ground.

Is B+ present?

Yes	No
SERVICE short to B+ in Circuit 224 (T/W). REASSEMBLE system. CONFIRM fix with NGS Tester PID "CPP."	Short to B+ at Pin 29 in PCM. INSPECT pin connector and pins. SERVICE as necessary. REASSEMBLE system. GO to AK12.

AK5 CHECK FOR PID "CPP" OPEN

Does PID "CPP" read ON (0v) only?

Yes	No
GO to AK6.	Fault may be intermittent. GO to AK13.

AK6 CHECK FUSE

Check fuse 17 (10 amp) — F-Series or fuse 18 (15 amp) — Econoline in IP fuse panel.

Is the fuse blown?

Yes	No
LOOK for short to ground. GO to AK7.	LOOK for open circuit. GO to AK9.

AK7 CHECK CIRCUIT 640 (R/Y) FOR SHORT TO GROUND

(TCS plugged)
Check resistance between TCS connector contact for Circuit 640 (R/Y) and chassis ground.

Is resistance less than 5 ohms?

Yes	No
SERVICE short to ground in Circuit 640 (R/Y). REPLACE fuse. REASSEMBLE system. CONFIRM fix with NGS Tester PID "CPP."	GO to AK8.

AK8 CHECK CIRCUIT 224 (T/W) FOR SHORT TO GROUND

(TCS unplugged)
Key off.
Unplug PCM.
Key on.
Check resistance between TCS connector contact for Circuit 224 (T/W) and chassis ground.

Is resistance less than 5 ohms?

Yes	No
SERVICE short to ground in Circuit 224 (T/W). REASSEMBLE system. CONFIRM fix with NGS Tester PID "CPP."	Short to ground is at PCM Pin 29. INSPECT PCM connector and PCM pins. SERVICE as necessary. REASSEMBLE system. GO to AK12.

AK9 CHECK CIRCUIT 640 (R/Y) FOR OPEN

(TCS unplugged)
Unplug fuse 17 (10 amp) — F-Series or fuse 18 (15 amp) — Econoline in IP fuse panel.
Key on, engine off.
Check voltage between Circuit 640 connector contact at TCS connector and fuse contact on Circuit 640 (R/Y) side.

Is resistance less than 5 ohms?

Yes	No
Circuit 640 (R/Y) is OK. GO to AK10.	SERVICE open in Circuit 640 (R/Y). REASSEMBLE system. CONFIRM fix with NGS Tester PID "CPP."

AK10 CHECK TCS FOR OPEN

(TCS unplugged)
Key on.
Jumper between TCS connector contacts for Circuits 640 (R/Y) and 224 (T/W).
Check NGS Tester PID "CPP."

Does PID read OFF (12v)?

Yes	No
REPLACE TCS/TCIL. REASSEMBLE system. CONFIRM fix with NGS Tester PID "CPP."	GO to AK11.

AK11 CHECK CIRCUIT 224 (T/W) FOR OPEN

(TCS unplugged)
Key off.
Unplug PCM.
Inspect 104 pin connector and repair as required.
Attach 104 pin breakout box.
Leave PCM disconnected.
Key on.
Check voltage between Test Pin 29 and connector contact for Circuit 224 (T/W).

Is resistance less than 5 ohms?

Yes	No
Circuit 224 (T/W) is OK. OPEN is at PCM Pin 29. INSPECT PCM connector and pins and REPAIR as required. REASSEMBLE system. GO to AK12.	SERVICE open in Circuit 224 (T/W). REASSEMBLE system. CONFIRM fix with NGS Tester PID "CPP."

AK12 CONFIRM PCM FAULT

Key on, engine off.
Check NGS Tester PID "CPP."

Does PID switch between ON and OFF?

Yes	No
SYSTEM is OK.	REPLACE PCM. CONFIRM fix with NGS Tester PID "CPP." RUN Self Test.

AK13 CHECKS FOR INTERMITTENT OPEN OR SHORT

(TCS unplugged)
Key on, engine off.
Jumper between TCS connector contacts for Circuits 640 (R/Y) and 224 (T/W).
Confirm that NGS Tester PID "CPP" shows OFF (12v).
Wiggle connectors and wires while watching "CPP" on NGS Tester.

Does PID switch between OFF and ON?

Yes	No
SERVICE circuitry at point of intermittent. REASSEMBLE system. CONFIRM fix with NGS Tester PID "CPP."	GO to AK14.

AK14 CHECK FOR INTERMITTENT SHORT TO B+

(TCS unplugged)
Key on, engine off.
Remove fuse 17 (10 amp) — F-Series or fuse 18 (15 amp) — Econoline in IP fuse panel.
Jumper between TCS connector contacts for Circuits 640 (R/Y) and 224 (T/W).
Confirm that NGS Tester PID "CPP" shows ON (0v).
Wiggle connector and wires while watching "CPP" on NGS Tester.

Does PID switch between ON and OFF?

Yes	No
SERVICE circuitry at point of intermittent contact with B+ source. INSTALL fuse. REASSEMBLE system. CONFIRM fix with NGS Tester PID "CPP." RUN Self Test.	Intermittent not detected. REASSEMBLE system. CONFIRM fix with NGS Tester PID "CPP." RUN Self Test.

AK15 DIAGNOSTIC TROUBLE CODE (DTC) 1779: CHECK TCIL

DTC 1779: TCIL circuit malfunction.
Key on, engine off.
Cycle TCS several times.

Does TCIL toggle on and off?

Yes	No
System is OK.	GO to AK16.

AK16 CHECK CIRCUIT 911 (W/LG) FOR SHORT TO B+

Unplug TCS connector.
Key on, engine off.
Measure voltage between connector contact for 911 (W/LG) and chassis ground.

Is B+ present?

Yes	No
GO to AK17.	GO to AK18.

AK17 CHECK PCM FOR SHORT TO B+

(TCS unplugged)
Unplug PCM.
Measure voltage between connector contact for 911 (W/LG) and chassis ground.

Is B+ present?

Yes	No
SERVICE Circuit 911 (W/LG) for short to B+. REASSEMBLE system. CONFIRM proper TCIL operation.	Short to B+ is at PCM Pin 79. INSPECT connector and pins. SERVICE as necessary. GO to AK21.

AK18 CHECK FOR FAULT TCS/TCIL

Unplug TCS connector.
Key on, engine off.
Measure voltage between connector contact for 911 (W/LG) and chassis ground.
Run KOEO Output State Self Test.

Does voltage toggle between B+ and 0v?

Yes	No
REPLACE TCS/TCIL. REASSEMBLE system. CONFIRM proper TCIL operation.	GO to AK19.

AK19 CHECK CIRCUIT 911 (W/LG) FOR SHORT TO GROUND

(TCS unplugged)
Key off.
Unplug PCM.
Key on.
Check resistance between TCS connector contact for Circuit 911 (W/LG) and chassis ground.

Is resistance greater than 10,000 ohms?

Yes	No
GO to AK20.	SERVICE short to ground in Circuit 911 (W/LG). REASSEMBLE system. CONFIRM proper TCIL operation.

AK20 CHECK CIRCUIT 911 (W/LG) FOR OPEN

(TCS unplugged)
Key off.
Unplug PCM.
Inspect 104 pin connector and repair as required.
Attach 104 pin breakout box.
Leave PCM disconnected.
Key on.
Check voltage between Test Pin 79 and connector contact for Circuit 911 (W/LG).

Is resistance less than 5 ohms?

Yes	No
Circuit 911 (W/LG) is OK. Open is at PCM Pin 79. INSPECT PCM connector and pins and REPAIR as required. REASSEMBLE system. GO to AK21.	SERVICE open in Circuit 911 (W/LG). REASSEMBLE system. CONFIRM proper TCIL operation.

AK21 CONFIRM PCM FAULT

Key on.
Cycle TCS several times.

Does TCIL toggle on and off?

Yes	No
SYSTEM is OK.	REPLACE PCM. CONFIRM proper TCIL operation. RERUN Self Tests.