GM Service Manual Online
For 1990-2009 cars only

Object Number: 595423  Size: MF

Circuit Description

The electrically erasable programmable read only memory (EEPROM) stores the electronic variable orifice (EVO)/Passlock™ module calibrations. The EVO/Passlock™ module performs internal tests on the EEPROM. The EVO/Passlock™ module indicates if any calibration faults (checksum errors) are current.

Conditions for Setting the DTC

A code sets when the EVO/Passlock™ module detects an internal calibration fault (checksum error).

Action Taken When The DTC Sets

The EVO/Passlock™ module will not send any current to the power steering solenoid actuator. This will cause the retraction of the power steering solenoid actuator valve, providing maximum fluid flow and full power steering assist at all times.

Conditions for Clearing the DTC

After the ignition is cycled, the properly programmed EVO/Passlock™ module indicates no internal calibration faults (checksum errors).

Diagnostic Aids

The EEPROM is not removable from the EVO/Passlock™ module. Replace the module, if service is required. Refer to Electronic Variable Orifice (EVO)/Passlock™ Module Replacement.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step makes sure that the Variable Effort Steering System Check is completed.

  2. This step checks if the EVO/Passlock™ module was previously replaced.

Step

Action

Value(s)

Yes

No

1

Was the Variable Effort Steering System Check performed?

--

Go to Step 2

Go to Variable Effort Steering System Check

2

  1. Cycle the ignition to the OFF position.
  2. Then turn the ignition to the ON position.

  3. Clear the DTCs

Is DTC C0559 set?

--

Go to Step 3

Go to Variable Effort Steering System Check

3

Replace the EVO/Passlock™ module. Refer to Theft Deterrent Module Replacement in Theft Deterrent.

Is the repair complete?

--

Go to Variable Effort Steering System Check

--