Section 208 (Diagnosis - 42RE (W/TCM)): Description

WARNING: This page is about a different car, the 1995 Jeep Grand Cherokee. However, it is still accessible from the selected car via links, so may be relevant.

The 42RE transmission uses an electronic system for monitoring governor pressure which is used to control transmission shifting. Electronic control system consists of Transmission Control Module (TCM), governor pressure solenoid, governor pressure sensor, transmission fluid temperature sender, OD (Overdrive) OFF switch, Throttle Position (TP) sensor and output shaft speed sensor. This vehicle is also equipped with a separate Powertrain Control Module (PCM) which controls engine operation and performance.

NOTE: Governor pressure sensor may be referred to as governor pressure transducer. Transmission fluid temperature sensor may be referred to as transmission fluid temperature thermistor. Output shaft speed sensor may also be referred to as transmission shaft speed sensor or shaft speed sensor.

Transmission shifting is controlled by throttle and governor pressure. Governor pressure is generated by electronic components through control of line pressure. Transmission will not upshift into 4th gear under following conditions:

3rd gear upshift is not complete.
OD OFF switch is in OFF position.
Throttle is at 3/4 to WOT position.
Vehicle speed is too low for 3-4 upshift.
Transmission fluid temperature is less than 30°F (-1°C).