The expansion spring brakes (ESB) are used on both front and rear actuator motor assemblies. The spring expands to provide friction to prevent the modulator piston from being back-driven by hydraulic pressure. This condition will disable rear base brakes and turn On the antilock and brake telltale lamp.

Code 42 sets if:

Rear ESB does not hold motor.

Code 86 will also set.

This code can only set during initialization 13 km/h (8 mph).

This code can be set after an ABS stop if this channel did not get into ABS.

The ESB is an internal component of the ABS motor pack and can not be serviced separately. If it is determined to be faulty, the motor pack must be replaced.

Use Scan tool to perform ABS motor tension release special test before removing motor pack.

When the ignition is cycled On, the ABS module verifies motors are in home position.

The ABS system will initialize (run motors down then up) when the vehicle is driven at least 13 km/h (8 mph) after start-up.

When attempting to diagnose an intermittent problem, use the Scan tool to review supplemental diagnostic information. The supplemental data can be used to duplicate a problem.