42 2-4 Solenoid Circuit

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THEORY OF OPERATION:
Four solenoids are used to control the friction elements (clutches). The continuity of the solenoids circuits are periodically tested. Each solenoid is turned on or off depending on it's current state. An inductive spike should be detected by the TCM during this test. If no spike is detected, the circuit is tested again to verify the failure. In addition to the periodic testing, the solenoid circuits are tested if a speed ratio or pressure switch error occurs. In this case, one failure will result in the code being set.

LIMP-IN:
YES

WHEN MONITORED/SET CONDITIONS:
Ignition key is turned from "off" position to "run" position and/or ignition key is turned from "crank" position to "run" position, then every 10 seconds thereafter, or when a speed ratio or pressure switch error fault is detected.

All four solenoids are tested for continuity continuously during vehicle operation. For solenoids that are currently energized, power is momentarily interrupted, then reenergized. For solenoids that are not currently energized the solenoid is momentarily energized then, deenergized. Under both situations, if an inductive spike is not sensed by the Transmission Control Module (TCM) during the continuity check, it is retested again. If it fails the test four times (three times for 89-93 model year), the appropriate code is set.

TRANSMISSION EFFECTS:
89-95 model year + 96 model year V-1 calibration - Transmission goes into neutral if code is set above 45 MPH, limp-in mode when vehicle speed is below 45 MPH.

96 model year V-2 calibration (default desensitization) and 97 model year - Transmission goes into neutral if code is set above 22 MPH, limp-in mode when vehicle speed is below 22 MPH.

POSSIBLE CAUSES:
- Open or shorted solenoid circuit(s) between TCM and solenoid pack.
- Open ground circuit.
- TCM connector problem.
- 8 way connector problem
- Defective solenoid pack.
- Defective TCM.