DTC 66: Adjuster Assembly Control: Notes

Power and ground are supplied to adjuster assembly which controls engine torque during TCS operation. During TCS operation, if EBTCM delivers current greater than 16 amps to adjuster assembly for longer than 3 seconds without adjuster assembly reaching desired position, DTC 66 will be set. SERVICE ASR indicator light will illuminate and TCS will be disabled. ABS remains functional. For system schematic, see Figure.

Fig 1: DTC 66 Diagnostic Flow Chart

Courtesy of GENERAL MOTORS CORP.

1. Checks for DTC 65 conditions, which can affect DTC 66.
2. Checks for mechanical binding of adjuster assembly, attached cables and related components. Binding would cause excessive load on adjuster assembly.
3. Because DTC 66 will only set during TCS operation, vehicle is raised to force TCS operation by allowing rear wheels to spin while front wheels remain still. To ensure parameters are met when checking for DTC 66 to reset, throttle opening must be greater than 15 percent, but less than 50 percent for system to attempt TCS control for more than 3 seconds.