For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### DTC Descriptors

DTC P1396: Wheel Speed Sensor Circuit w/o ABS
DTC P1397: Wheel Speed Sensor Circuit w/ABS

### Circuit/System Description

The engine control module (ECM) determines engine misfire by detecting variations in crankshaft speed. Crankshaft speed variations can also occur when a vehicle is operating over a rough road. The wheel speed sensor produces an alternating current (AC) voltage that increases with wheel speed. The ECM receives a rough road signal from an electronic brake control module (EBCM), if equipped with the ABS. The ABS can determine if the vehicle is on a rough road surface based on the signal from each wheel speed sensor. On vehicles with Non-ABS, a rough road signal is sent from a wheel speed sensor located at the left front wheel to the ECM. The ECM can determine if the vehicle is on a rough road surface based on the signal from the wheel speed sensor. When the ECM detects a rough road condition, misfire diagnostics will be disabled.

### Conditions for Running the DTC

• | DTCs P0106, P0107, P0108, P0115, P0116, P0117, P0118, P0122, P0123, P0125, P0128, P0201, P0202, P0203, P0204, P0217, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0300, P0351, P0352, P0402, P0404, P0405, P0406, P042E and P0488 are not set.

• | The engine run time is greater than 10 seconds.

• | The engine coolant temperature (ECT) is greater than or equal to 60°C (140°F).

• | The ignition voltage is between 11-16 volts.

• | The DTCs run continuously once the above condition is met.

### Conditions for Setting the DTC

#### P1396

The ECM detects an invalid rough road signal from the wheel speed sensor.

#### P1397

The ECM detects an invalid rough road signal from the EBCM.

### Action Taken When the DTC Sets

DTC P1396 and P1397 are type C DTCs

### Conditions for Clearing the DTC

DTC P1396 and P1397 are type C DTCs

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

1. Engine running, observe the DTC information with a scan tool. DTCs P1396 or P1397 should not set.
2. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

### Circuit/System Testing

Important: If the ABS lamp is illuminated, the ABS system must be diagnosed prior to using this diagnostic procedure. Refer to Diagnostic System Check - Vehicle.

1. Ignition OFF, disconnect the harness connector at the wheel speed sensor or the EBCM, if equipped with ABS.
2. Ignition OFF, test for less than 5 ohms between the low reference circuit and ground.

⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

• | Wheel Speed Sensor LF low reference circuit terminal B

• | Wheel Speed Sensor LR low reference circuit terminal B

• | Wheel Speed Sensor RF low reference circuit terminal A

• | Wheel Speed Sensor RR low reference circuit terminal A

3. Ignition ON, test for 4.8-5.2 volts on the signal circuit.

• | Wheel Speed Sensor LF signal circuit terminal A

• | Wheel Speed Sensor LR signal circuit terminal A

• | Wheel Speed Sensor RF signal circuit terminal B

• | Wheel Speed Sensor RR signal circuit terminal B

⇒ | If less than the specified range, test the signal circuit for a short to ground or an open. If the circuit tests normal, replace the ECM.

⇒ | If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.

4. If all circuits test normal, test or replace the wheel speed sensor or EBCM, if equipped with ABS.

### Component Testing

Important: This procedure is for a vehicle without ABS. If the wheel speed sensor harness is damaged in any way, DO NOT repair the harness.

1. Ignition OFF, disconnect the harness connector at the wheel speed sensor.

Notice: Support the lower control arms in the normal horizontal position in order to avoid damage to the drive axles. Do not operate the vehicle in gear with the wheels hanging down at full travel.

2. Raise and support the drive wheels.
3. Engine idling, place the transmission into 2nd gear or drive for an automatic.
4. Test for 70 mV AC between the rough road signal terminal and low reference terminal.

⇒ | If less than the specified range, replace the wheel speed sensor.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for engine control module or electronic brake control module replacement, setup, and programming