Chart C-8B Torque Converter Fluid Temp Switch Check

Chart C-8B.:

Torque Converter Fluid Temperature Switch Circuit.:

CIRCUIT DESCRIPTION
The torque converter fluid temperature switch, is a normally open temperature sensitive switch which sends a signal to the Powertrain Control Module (PCM) to begin action to cool the torque converter. At 164°C (327°F) the switch will close and the signal to the PCM will change to zero volts. The PCM will then command a 4-3 down shift and apply the Torque Converter Clutch (TCC) in second and third gears. This switch is a single lead switch which grounds through the transmission fluid cooler pipes.

CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.

1. This step verifies the electrical integrity of the wiring and PCM input.

DIAGNOSTIC AIDS
To verify that the TCC temperature switch closes at 164°C (327°F). It will be necessary to use a surface thermometer and a heat gun. Remove TCC temperature switch before testing.

If the TCC temperature switch and external wiring checks okay, verify circuit ground integrity through the trans fluid cooler pipes.