Pinpoint Test B : Transmission Control Switch (TCS) Does Not Operate Properly

WARNING: This page is about a different car, the 2019 Ford F-550 Super Duty, 2019 Ford F-450 Super Duty, 2019 Ford F-350 Super Duty, and 2019 Ford F-250 Super Duty. However, it is still accessible from the selected car via links, so may be relevant.

Refer to Transmission Controls - Torqshift 6 for schematic and connector information.

Normal Operation and Fault Conditions

The TCS is a momentary contact switch located on the end of the selector lever. Pressing the TCS will engage or disengage the Tow/Haul function of the transmission, which delays upshifts to reduce the frequency of transmission shifting and provides engine braking to slow the vehicle and assist the driver in controlling the vehicle when descending a hill. When Tow/Haul is engaged, the Tow/Haul icon illuminates on the IPC. Each time the ignition switch is cycled, the PCM disengages the Tow/Haul operation regardless of the switch position the last time the engine was running.

DTC Fault Trigger Conditions

DTC	Description	Fault Trigger Condition
PCM P1780:00	Transmission Control Switch (O/D Cancel) Circuit Out Of Self Test Range: No Sub Type Information	This DTC can only set during the KOER on-demand self-test, and indicates the TCS circuit tested out of range.
TCM P1780:00	Transmission Control Switch (O/D Cancel) Circuit Out Of Self Test Range: No Sub Type Information	This DTC can only set during the KOER on-demand self-test, and indicates the TCS circuit tested out of range.

Possible Sources

Connectors damaged or pushed-out terminals, corrosion, loose wires and missing or damaged seals
BCM fuse 19 (7.5A)
TCS
PCM
TCM

B1 RETRIEVE AND RECORD ALL DIAGNOSTIC TROUBLE CODES (DTCS)

Using a diagnostic scan tool, carry out the KOEO and KOER PCM (gasoline engine vehicles) or TCM (diesel engine vehicles) self-test.

Is DTC P1780 present?

Yes

GO to B2

No	The TCS circuit is operating properly at this time. If the Tow/Haul lamp does not illuminate, REFER to: Information Center - Instrumentation, Message Center And Warning Chimes .

B2 CHECK THE TCS (TRANSMISSION CONTROL SWITCH) POWER CIRCUIT FOR VOLTAGE

Ignition OFF.

Disconnect Tow/Haul Switch C2399.

Inspect for damaged or pushed-out terminals.

Ignition ON.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C2399-1	Courtesy of FORD MOTOR COMPANY	Ground

Is the voltage greater than 11 volts?

Yes

GO to B3

No	CHECK the BCM fuse 19 (7.5A). If the fuse is OK, REFER to OEM Wiring Diagrams to diagnose and repair the open circuit. If the fuse is not OK, REFER to OEM Wiring Diagrams to diagnose and repair the short to ground.

B3 CHECK THE TOW/HAUL SWITCH INPUT CIRCUIT FOR AN OPEN

Disconnect PCM C175B (for vehicles equipped with a gasoline engine).

Disconnect TCM C1750 (for vehicles equipped with a diesel engine).

Inspect for damaged or pushed-out terminals.

For vehicles equipped with a gasoline engine, measure:

Positive Lead	Measurement / Action	Negative Lead
C2399-2	Courtesy of FORD MOTOR COMPANY	C175B-93

For vehicles equipped with a diesel engine, measure:

Positive Lead	Measurement / Action	Negative Lead
C2399-2	Courtesy of FORD MOTOR COMPANY	C1750-19

Is the resistance less than 3 ohms?

Yes

GO to B4

No	REPAIR the circuit.

B4 CHECK THE TOW/HAUL SWITCH

Measure:

Positive Lead	Measurement / Action	Negative Lead
Courtesy of FORD MOTOR COMPANY Tow/Haul switch component side, pin 1	Courtesy of FORD MOTOR COMPANY	Courtesy of FORD MOTOR COMPANY Tow haul switch component side, pin 2

Is the resistance less than 3 ohms with the switch pressed, and greater than 10, 000 ohms with the switch released?

Yes

GO to B5

No	INSTALL a new selector lever, REFER to: Selector Lever .

B5 CHECK THE PCM OR TCM

Connect BCM C2280B.

Connect Tow/Haul Switch C2399.

Ignition ON.

For vehicles equipped with a gasoline engine, measure:

Positive Lead	Measurement / Action	Negative Lead
C175B-93	Courtesy of FORD MOTOR COMPANY	Ground

For vehicles equipped with a diesel engine, measure:

Positive Lead	Measurement / Action	Negative Lead
C1750-19	Courtesy of FORD MOTOR COMPANY	Ground

Is the voltage greater than 11 volts with the switch pressed, and less than 5 volts with the switch released?

Yes

For vehicles equipped with a gasoline engine, Refer to PCM Guided Routine . After installing a new PCM, CARRY OUT the transmission strategy download. REFER to: Transmission Strategy Download . For vehicles equipped with a diesel engine, INSTALL a new TCM. REFER to: Transmission Control Module (TCM) . CARRY OUT the transmission strategy download. REFER to: Transmission Strategy Download .

No	REPAIR the circuit.