| CAUTION | If Engine Control Module (ECM) replacement is instructed in following test, always ensure ECM electrical connectors and ground circuits are okay. If either are defective, repair and repeat testing to confirm ECM malfunction. If ECM is replaced, ECM must be programmed with proper ignition key code for engine immobilizer system. For programming procedures, see COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION, or appropriate ENGINE IMMOBILIZER SYSTEMS article in ACCESSORIES & EQUIPMENT. |
Circuit Description
Vehicle speed sensor outputs a 4-pulse input signal for every revolution of the drive gear in transmission to the instrument cluster where input signal is converted to a rectangular waveform and then sent to ECM. ECM determines vehicle speed by using input signal. DTC is set if there is no vehicle speed signal to ECM while vehicle is being driven and park/neutral position switch is off. Possible causes are
- Defective vehicle speed sensor.
- Vehicle speed sensor circuit is open or shorted.
- Defective instrument cluster.
- Defective ECM.
Diagnostic Aids
This DTC uses two-trip detection logic. Using Toyota hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.