Ford F150 Pickup. Manual - part 1581

Fig. 362: Identifying TCIL & TCS Circuits & Connector Terminals (Econoline, Excursion, Expedition, 
Navigator & Pickup) 
Courtesy of FORD MOTOR CO. 

Fig. 363: Identifying TCS Circuits & Connector Terminals (Aviator, Explorer, LS & Mountaineer) 
Courtesy of FORD MOTOR CO. 

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline

  

Fig. 364: Identifying TCIL & TCS Circuits & Connector Terminals (All Others) 
Courtesy of FORD MOTOR CO. 

Testing 

1) For KOER Only DTC P1780: Check Transmission Control Switch Function 
DTC P1780 indicates Transmission Control Switch (TCS) was not cycled during KOER self-test. 
Possible causes are: 

z

TCS Not Cycled During Self-Test  

z

Faulty TCS  

z

TCS Circuit Open Or Shorted  

z

Faulty PCM  

Turn ignition switch to ON position. Using scan tool, access TCS PID from PID/DATA MONITOR & 
RECORD menu. Cycle TCS switch, hold switch depressed for 3 seconds, then release switch. Turn 
ignition switch to OFF position. If TCS PID value switched from ON to OFF, then indicated ON when 
switch was depressed, repeat KOER ON-DEMAND SELF-TEST, ensuring to cycle TCS. If TCS PID 
did not indicate as specified, go to step 10) (Windstar), or next step (all others). 

2) Check Voltage To TCS 
 
Turn ignition switch to OFF position. Disconnect PCM connector(s). Inspect connector for loose, 
damaged or corroded terminals. Repair as necessary. Turn ignition switch to ON position. Using a 
DVOM, measure voltage between negative battery terminal and TCS circuit at PCM harness connector 

NOTE:

For additional testing information, see DIAGNOSTIC AIDS.

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline

  

while cycling TCS. See PCM CONNECTOR IDENTIFICATION and Fig. 362-Fig. 364 . If voltage 
does not cycle when TCS is cycled, go to next step. If voltage cycles when TCS is cycled, replace PCM 
and repeat QUICK TEST. 

3) Check TCS Circuit For Short To Ground In Harness 
 
Turn ignition switch to OFF position. Disconnect TCS connector. Inspect connector for loose, damaged 
or corroded terminals. Repair as necessary. Using a DVOM, measure resistance of TCS circuit between 
negative battery terminal and PCM harness connector. If resistance is more than 10 k/ohms, go to next 
step. If resistance is 10 k/ohms or less, repair short to ground in TCS circuit. 

4) Check TCS Circuit For Open In Harness 
 
Using a DVOM, measure resistance of TCS circuit between TCS harness connector and PCM harness 
connector. Also, measure resistance of TCS KEY PWR circuit between TCS harness connector and 
appropriate TCS fuse in junction box. See PCM CONNECTOR IDENTIFICATION and Fig. 362-Fig. 
364 . See WIRING DIAGRAMS for TCS fuse identification. If both resistances are less than 5 ohms, go 
to next step. If either resistance is 5 ohms or more, repair open TCS circuit. 

5) Check TCS Circuit For Short To PWR In Harness 
 
Using a DVOM, measure resistance between TCS and VPWR circuits at PCM harness connector. If 
resistance is more than 10 k/ohms, replace faulty TCS. If resistance is 10 k/ohms or less, repair short to 
VPWR in TCS circuit. 

6) TCIL Always ON With Engine Running (No DTCs): Check TCIL Function 
Turn ignition switch to ON position. Cycle Transmission Control Switch (TCS). If TCIL illuminates and 
then goes off, fault is unable to be duplicated at this time. Go to TEST Z, step 1). If TCIL does not 
illuminate and then go off, go to next step. 

7) Check TCIL Circuit For Short to Ground In Harness 
 
Turn ignition switch to OFF position. Disconnect PCM connector. Inspect connector for loose, damaged 
or corroded terminals. Repair as necessary. Turn ignition switch to ON position. If TCIL turned off with 
PCM disconnected, replace PCM. If TCIL remains illuminated, repair short to ground in TCIL circuit. 
See Fig. 362-Fig. 364 . See WIRING DIAGRAMS. 

8) TCIL Never ON: Check For DTC P1780 
 
Perform KOER ON-DEMAND SELF-TEST. If DTC P1780 is not present, go to next step. If DTC 
P1780 is present, go to step 1). 

NOTE:

Diagnostic procedures beginning with step 6) are performed when 
directed here from WARNING INDICATOR LIGHTS under SYMPTOMS in 
TROUBLE SHOOTING - NO CODES - CNG, FLEX-FUEL & GASOLINE 
article.

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline

  

9) Check Voltage To TCIL 
 
Turn ignition switch to OFF position. Disconnect PCM connector. Inspect connector for loose, damaged 
or corroded terminals. Repair as necessary. Turn ignition switch to ON position. Using a DVOM, 
measure voltage between negative battery terminal and TCIL circuit at PCM harness connector. See 
PCM CONNECTOR IDENTIFICATION and Fig. 362-Fig. 364 . If voltage is more than 2 volts, check 
wiring harness between TCIL and PCM for an open or short circuit. See WIRING DIAGRAMS. If no 
fault exists, replace PCM. If voltage is 2 volts or less, check TCIL bulb and fuse. Repair as necessary. If 
bulb and fuse are okay, repair open in circuit between PCM harness connector and TCIL, or between 
TCIL and power supply. See WIRING DIAGRAMS. 

10) Check VPWR Voltage To Transmission Control Switch 
 
Turn ignition switch to OFF position. Disconnect Transmission Control Switch (TCS) connector. Turn 
ignition switch to ON position. Using a DVOM, measure voltage between chassis ground and VPWR 
circuit at TCS harness connector terminal No. 2 (Red/Yellow wire). If voltage is more than 10 volts, go to 
next step. If voltage is 10 volts or less, repair open in Red/Yellow wire between TCS and central junction 
box. See ANALOG INSTRUMENT PANELS in appropriate SYSTEM WIRING DIAGRAMS article in 
ELECTRICAL. Verify system operation. 

11) Check Transmission Control Switch 
 
Turn ignition switch to OFF position. Using a DVOM, measure resistance between both TCS terminals, 
while pressing and releasing switch. Resistance should be less than 5 ohms with TCS button depressed, 
and more than 10 k/ohms with TCS button released. If resistance is as specified, go to next step. If 
resistance is not as specified, replace TCS. Verify system operation. 

12) Check Light Blue/Yellow Wire For An Open 
 
Ensure ignition switch is turned to OFF position. Disconnect Instrument Cluster Module (ICM) 22-pin 
connector C220c. Using a DVOM, measure resistance of Light Blue/Yellow wire between TCS harness 
connector and ICM harness connector C220c terminal No. 21. See Fig. 365. If resistance is less than 5 
ohms, replace ICM. Verify system operation. If resistance is 5 ohms or more, repair open in Light 
Blue/Yellow wire between TCS and ICM. Verify system operation. 

 

2003 Ford Pickup F150 

2003 ENGINE PERFORMANCE Self-Diagnostics - CNG, Flex-Fuel & Gasoline