DTC C0495 EVO Tracking Error. Chevrolet Astro

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 1998 🢒 Astro - 4WD 🢒 Steering 🢒 Variable Effort Steering 🢒 DTC C0495 EVO Tracking Error

DTC C0498

Steering Controls Components
Steering Assist Schematics
Handling ESD Sensitive Parts Notice

The electronic variable orifice (EVO)/Passlock™ module supplies a 0-850 milliamperes percentage duty cycle current to the steering assist control solenoid. The current extends or retracts the actuator valve inside the solenoid. The extension or retraction will regulate an orifice on the power steering pump. The regulated orifice will cause the fluid flow output to modulate. The fluid flow output will increase or decrease in steering wheel effort. Supplying a 0 milliampere to the steering valve control solenoid will fully retrace the valve. This provides the maximum fluid flow and power steering assist. Suppling 850 milliamperes to the steering assist control solenoid extends the valve. The extended valve will decrease the fluid flow and minimize the power steering assist. The EVO/Passlock™ module constantly adjusts the current flow to the steering assist control solenoid based on the vehicle speed and the steering wheel position. The adjusting current flow provides vehicle speed related power steering assist.

Conditions for Setting the DTC

There is an open, or a short to ground, or a short to voltage in the following circuits while the EVO/Passlock™ module is pulsing the current to the steering assist control solenoid:

•	CKT 1294 (WHT)

•	CKT 1295 (BRN)

The following conditions are necessary for setting the DTC:

The voltage is below 0 volts.
The voltage is at the battery voltage.
The conditions must be met for 1 second or longer.

Action Taken When the DTC Sets

The EVO/Passlock™ module will not send any current to the steering assist control solenoid. This will cause the solenoid valve to retract. The retracting valve will provide the maximum fluid flow and full power steering assist at all time.

Conditions for Clearing the MIL/DTC

•	A history DTC will clear after 100 consecutive ignition cycles occur without a fault.

•	Use a scan tool in order to clear the history and the current DTC(s).

Diagnostic Aids

Perform the following code tests first if DTC C0498, DTC C0499, DTC C0502 or DTC C0503 are present:

•	The following conditions may cause an intermittent problem:

•	A poor connection.

•	A break in the wire insulation that exposes the internal wire.

•	A wire that is broken on the inside of the insulation.

•	Thoroughly check the EVO/Passlock™ module and the vehicle control module (VCM) for the following conditions:

•	Backed out terminals

•	Broken locks

•	Improperly formed terminals

•	Damaged terminals

•	Weak terminal retaining tension

•	Proper routing

•	The solenoid valve may be stuck. The stuck valve provides uncalculated power steering assist.

Refer to Power Steering System Test in Power Steering System.

Test Description

The number(s) below refer to the step number(s) on the diagnostic table.

This step ensures that you perform the Diagnostic System Check.

This step check for a short to voltage in CKT 1294 (WHT) or CKT 1295 (BRN) with the EVO/Passlock™ module disconnected.

This step checks for the commanded and the actual duty cycle.

This step check the steering assist control solenoid harness for a short to voltage with the solenoid disconnected on CKT 1294 (WHT) and CKT 1295 (BRN).

This step checks the steering assist control solenoid harness for a short to ground. This steps check for an open with the solenoid disconnected on CKT 1294 (WHT) and CKT 1295 (BRN).

If voltage is indicated, there is a short to voltage on CKT 1294 (WHT) or CKT 1295 (BRN).

If the voltage is 0, there is a short to ground on CKT 1294 (WHT) or CKT 1295 (BRN).

Step

Action

Value(s)

Yes

Did you perform the Diagnostic System Check?

Go to Step 2

Go to the Diagnostic System Check

Turn the ignition switch to the OFF position.
Connect the scan tool.
Turn the ignition switch to the ON position.
Select the CHASSIS MENU, ELECTRONIC VARIABLE ORIFICE (EVO).
Check for the following DTCs:

•

DTC C0498

•	Refer to DTC C0498 Steering Assist Control Actuator Feed Circuit Low .

•

DTC C0499

•	Refer to DTC C0499 Steering Assist Control Solenoid Feed Circuit High .

•

DTC C0502

•

DTC C0503

•	Refer to DTC C0503 Steering Assist Control Solenoid Return Circuit Low .

Did you find any DTC(s)?

Go to Diagnostic Trouble Code (DTC) List

Go to Step 3

Set the parking brake.
Block the drive wheels.
Start the vehicle.
Select the CHASSIS MENU, ELECTRONIC VARIABLE ORIFICE, SPECIAL FUNCTIONS.
Command the solenoid to the following ranges:

•

25%

•

50%

•

75%

•

100%

Monitor the commanded state of the solenoid.

Are the values equal?

Go to the Diagnostic System Check

Go to Step 4

Turn the ignition switch to the OFF position.
Disconnect the 16-way EVO/Passlock™ module connector.
Disconnect the steering assist control solenoid connector.
Turn the ignition switch to the ON position.
Use a J 39200 digital multimeter (DMM) in order to measure the voltage from terminal A3 to ground.
Use a J 39200 DMM in order to measure the voltage from terminal A1 to ground.

Is there voltage present?

Go to Step 5

Go to Step 6

Repair the short to voltage in CKT 1294 (WHT) or CKT 1295 (BRN) between the EVO/Passlock™ module and the steering assist control solenoid.

Is the repair complete?

Go to the Diagnostic System Check

Go to Step 6

Ensure that the EVO/Passlock™ module and the steering assist control solenoid remain disconnected.
Use a J 39200 DMM in order to measure for continuity from terminal A1 to ground.
Use the J 39200 DMM in order to measure for continuity from terminal A1 to ground.

Is any voltage present?

Go to Step 7

Go to Step 8

Repair the short to ground in CKT 1294 (WHT) or CKT 1295 (BRN) between the EVO/Passlock™ module and the steering assist control solenoid.

Is the repair complete?

Go to Step 9

The problem is intermittent.

Refer to Intermittents and Poor Connections Diagnosis in Wiring Repair.

Did you perform the intermittent diagnosis?