For 1990-2009 cars
Steering Controls Components
Steering Assist Schematics

### Circuit Description

When the EBCM commands the ABS enable relay ON, the ABS supplies battery voltage to the EVO actuator terminal A . The EBCM terminal 18 provides the ground for the EVO actuator through the actuator terminal B. The EBCM controls the amount of current supplied to the EVO actuator based on input from the following components:

• | The ABS wheel speed sensors.

• | The steering wheel speed sensor.

### Conditions for Setting the DTC

• | DTC C1273 can be set before ABS initialization or above 16 km/h (10 mph).

• | The EBCM detects the EVO actuator control circuit at ground before initialization.

• | The EVO actuator senses that the current is less than half the command current when the vehicle is above 16 km/h (10 mph).

### Action Taken When the DTC Sets

• | A malfunction DTC is stored.

• | The ABS/VES is disabled.

• | The ABS indicator lamp is turned ON.

• | The power steering returns to full assist.

### Conditions for Clearing the DTC

• | All ABS DTCs have been diagnosed and corrected.

• | DTC C1273 setting conditions no longer exist.

• | The ignition key is turned to OFF.

Clearing VES DTCs automatically clears ABS DTCs resulting in a loss of DTC history data. Refer to Diagnostic Aids.

### Diagnostic Aids

The EVO actuator is malfunctioning. Use the enhanced diagnostic function of the scan tool in order to verify the frequency of a malfunction. Refer to Enhanced Diagnostics in ABS/ETS.

An open or short to ground exists in any of the EVO actuator circuit wires. When diagnosing for an intermittent short or an open, massage the wiring harness while watching the test equipment for changes. An intermittent malfunction is most likely caused by one of the following conditions:

• | A wire in poor connection.

• | A wire that has rubbed through the insulation.

• | A wire that is broken inside the insulation.

• | A backed out terminal.

• | An improper mating.

• | A broken lock.

• | An improperly formed or damaged terminal.

• | A poor terminal to wiring connection.

• | A sign of physical damage to the wiring harness.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the ABS Diagnostic System Check? | -- | Go to Step 2 | Go to Diagnostic System Check
2 |

1. Turn the ignition switch to RUN.
2. Use the scan tool in order to select the following functions:

• | MISC TESTS

• | VES MANUAL CONTROL

• | Command EVO actuator ON

Is the feedback current greater than the specified value?

100 mA

Go to Step 14

Go to Step 3

3 |

1. Turn the ignition switch to OFF.
2. Disconnect the EBCM harness connector.
3. Disconnect the EVO actuator connector.
4. Use J 39200 in order to measure the resistance between the EVO actuator harness connector terminal B and the EBCM harness connector terminal 18.

Is the resistance within the specified range?

0-2 ohms

Go to Step 4

Go to Step 10

4 | Use J 39200 in order to measure the resistance between the EBCM harness connector terminal 18 and ground. Is the resistance within the specified range? | OL (Infinite) | Go to Step 5 | Go to Step 11
5 | Use J 39200 in order to measure the resistance between the EVO actuator harness connector terminal A and the EBCM harness connector terminal C. Is the resistance within the specified range? | 0-2 ohms | Go to Step 6 | Go to Step 12
6 | Use J 39200 in order to measure the resistance between the EBCM harness connector terminal C and ground. Is the resistance within the specified range? | OL (Infinite) | Go to Step 7 | Go to Step 13
7 |

1. Reconnect the EVO actuator connector.
2. Use J 39200 in order to measure the resistance between the EBCM harness connector terminal 18 and ground.

Is the resistance within the specified range?

OL

(Infinite)

Go to Step 8

Go to Step 15

8 | Use J 39200 in order to measure the resistance between the EBCM harness connector terminal 18 and C. Is the resistance within the specified range? | 7-19 ohms | Go to Step 9 | Go to Step 15
9 |

1. Inspect the EBCM harness connector and the EVO actuator harness connector for poor terminal contact or corrosion. Refer to Electrical Diagnosis, Checking Terminal Contact Cell 4. Replace any terminals with poor terminal contact or corrosion.
2. Inspect CKT 1295 for damage. A damaged CKT may result in a short to ground or an open with all connectors connected. Repair any damage.
3. Reconnect all connectors.
4. Turn the ignition switch to RUN.

Is DTC C1273 set as a current DTC?

--

Go to Step 16

Go to Step 14

10 | Repair the open or high resistance in CKT 1295. Did you complete the repair? | -- | Go to Diagnostic System Check | --
11 | Repair the short to ground in CKT 1295. Did you complete the repair? | -- | Go to Diagnostic System Check | --
12 | Repair the open or high resistance in CKT 1633 or CKT 855. Did you complete the repair? | -- | Go to Diagnostic System Check | --
13 | Repair the short to ground in CKT 1633 or in CKT 855. Did you complete the repair? | -- | Go to Diagnostic System Check | --
14 | Is the malfunction intermittent? | -- | Go to the Diagnostic Aids for this DTC | --
15 | Replace the EVO actuator. Refer to Variable Effort Steering Actuator Replacement . Did you complete the repair? | -- | Go to Diagnostic System Check | --
16 | Replace the EBCM. Refer to Electronic Brake Control Module Replacement in Antilock Brake System. Did you complete the repair? | -- | Go to Diagnostic System Check | --