For 1990-2009 cars
Steering Controls Components
00v-ves (fig sio)

### Circuit Description

The electronic brake/traction control module (EBTCM), transmits a processed vehicle speed signal (VSS) from terminal 23 to terminal 4 of the power steering control module (PSCM). The PSCM uses the speed signal and the characteristic curve programmed in the microprocessor to determine the electric current variable for the power steering fluid flow control valve actuator.

### Conditions for Setting the DTC

The power steering control module detects that the vehicle speed signal (VSS) is no longer present at terminal 4.

### Action Taken When the DTC Sets

• | Power steering assist will default to partial manual steering.

• | The PSCM will store a DTC 21 in memory.

### Conditions for Clearing the DTC

• | Conditions for the fault are no longer present.

• | Using the scan tool.

### Diagnostic Aids

Check for the following conditions if a history or intermittent DTC is indicated:

• | A poor connection at the PSCM. Inspect the harness connectors for backed out terminals, improper mating, improperly formed or damaged terminals, and poor terminal to wire connections.

• | A damaged wiring harness. Inspect the wiring harness for damage. If the wiring harness appears to be in good condition, observe the display on the DMM while moving the connectors and wiring harnesses related to the circuits. A change in the DMM display during this test will indicate the location of the fault.

• | For additional information, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

### Test Description

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

1. This step checks to see if the speedometer is operating properly.

2. This step checks for the speed signal input into the power steering control module.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Variable Effort Steering Diagnostic System Check? | -- | Go to Step 2 | Go to Diagnostic System Check - Variable Effort Steering
2 | Does the speedometer operate properly? | -- | Go to Step 3 | Go to Speedometer Inop in I/P, Guages and Console
3 |

1. Disconnect the power steering control module connector.
2. Raise the drive wheels.
3. Turn ON the ignition.
4. Use the DMM, on the AC scale, to measure the voltage between the control circuit of the electronic brake/traction control module and the ground circuit of the power steering control module while rotating the LH rear wheel. Refer to Measuring Frequency in Wiring Systems.

Is the measured voltage within the specified value?

Greater than 1 VAC

Go to Step 5

Go to Step 4

4 | Repair the open or the high resistance in the control circuit of the electronic brake/traction control module. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Step 6 | --
5 | Replace the power steering control module. Refer to Power Steering Control Module Replacement . Is the repair complete? | -- | Go to Step 6 | --
6 | Operate the system in order to verify the repair. Did you find and correct the condition? | -- | System OK | Go to Step 2