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 Descriptor

DTC P150A: Transmission Output Speed Signal Circuit
DTC P150B: Transmission Output Speed Sensor Circuit Intermittent

### Circuit/System Description

The vehicle speed sensor (VSS), also called the output shaft speed sensor (OSS) creates an AC voltage as the rotor teeth pass through the magnetic field of the sensor. The transmission control module (TCM) converts the AC voltage into a vehicle speed signal, which is used to determine shift timing and torque converter clutch (TCC) scheduling. The TCM also provides a replicated transmission output speed signal (RTOSS) to the engine control module (ECM).

### Conditions for Running the DTC

#### P150A

• | The TCM indicates the transmission output speed signal is valid.

• | Transmission output speed is 1,200 RPM or greater.

#### P150B

• | Transmission output speed is greater than 300 RPM for 2 seconds.

• | Transmission output speed has changed less then 500 RPM for 2 seconds.

### Conditions for Setting the DTC

#### P150A

The replicated output speed is 60 RPM or less for 4.5 seconds.

#### P150B

The change in replicated output speed is 350 RPM or greater for 3.25 seconds.

### Conditions for Clearing the DTC

#### P150A

• | P150A is a Type B DTC.

• | The replicated output speed is 150 RPM or greater for at least 3 seconds.

#### P150B

• | P150B is a Type B DTC.

• | Transmission output speed is 150 RPM or greater for at least 2 seconds.

• | The change in transmission output speed is 150 RPM or less for at least 3 seconds.

### Diagnostic Aids

• | A defective transmission output speed sensor (OSS) can cause inaccurate speed reading, creating faulty replicated output speed signal. Also, inspect the OSS for cracks, loose mounting, or damage.

• | If the speed sensor passes testing, refer to Testing for Intermittent Conditions and Poor Connections .

### Reference Information

#### Schematic Reference

Automatic Transmission Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Description and Operation

Transmission General Information

#### 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

Transmission Control Module Scan Tool Information

### Circuit/System Verification

If there are any other engine or transmission related DTCs set, diagnose those DTCs first. With a scan tool, observe the transmission output shaft speed sensor parameter for appropriate output RPM. Then in the engine controls data list, look for a functioning signal from the TCM.

### Circuit/System Testing

1. Ignition OFF, disconnect the ECM connector (X3).
2. Ignition ON, measure the voltage on the harness of the ECM connector (X3-66) for 5 V.

⇒ | If you have 5 V, test or replace the ECM.

⇒ | If the value is other than 5 V, test harness for:

• | Short to Voltage

• | Short to Ground

• | Open

3. If no trouble found, replace the TCM.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for ECM replacement, setup, and programming.