How to fix Ford Trucks No Torque Converter Clutch Application When Less Than 30 Percent Throttle?
Q: How to fix Ford Trucks No Torque Converter Clutch Application When Less Than 30 Percent Throttle?
A: We suggest you follow these steps to troubleshoot:
Common symptoms:
Some Ford Motor Company Trucks, 1996 and later, may exhibit a no Torque Converter
Clutch application at less than 30 percent throttle. No Trouble Codes present.
Common Cause:
Two possibilities:
1.One cause for this condition may be that one or more of the vehicle brake light bulbs,
including the High Mount brake light may be burned out, or have a damaged filament . When this condition is present, the PCM will detect an open in the brake lamp
circuit, and due to a pull-up resistor in the PCM, will output voltage from PCM terminal 92 to
the brake on-off switch. As a result, the Torque Converter Clutch will not be
applied at less than 30 percent throttle.
2.With some aftermarket LED lamp assemblies. The
main advantages of switching to LED lamp assemblies is that there are no fragile filaments to
burn out or break, which means that the LED lamp assemblies may possibly last for the entire
life of the vehicle, and LED lamps consume much less energy than the stock incandescent
bulbs. Due to the low power consumption, the PCM may view this reduced current draw as
being a burned out bulb, resulting in a no Torque Converter Clutch apply at less than 30
percent throttle.
Correction:
1.Prior to any part replacement or modifications, it would be recommended to check for a 5 to 8
volt DC signal coming out of the PCM at terminal 92 using a volt meter set to read DC
voltage. Voltage may also be checked at the Light Green wire located at the back of the Brake
On-Off Switch. This test will
help to confirm that a circuit fault has been detected by the PCM.
Normal operation will be 0 volts DC, brake off, and 12 volts DC, brake on.
Replace any burned out brake lamp bulbs, including the High Mount brake lamp bulb. It is also important to note, that a bad ground for the rear lamp assembly,
has also been known to cause the identical symptom.
2.Bulb assemblies, it may be necessary to install a 6 ohm- 50 watt Load Resistor across the
brake light power wire to simulate the load of the regular stock incandescent bulb . Note: One resistor is required for use on each LED bulb assembly.
The 6 ohm, 50 watt Load Resistors may be available from the suppliers of the LED bulb
assemblies.