| 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. On models equipped with engine immobilizer, 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 is located near rear of transaxle. Vehicle speed sensor outputs a 4-pulse input signal for every revolution of the drive gear in transaxle to the instrument cluster where input signal is converted to a rectangular waveform and then sent to the to ECM. DTC is set if there is no vehicle speed signal to ECM while vehicle is being driven. Possible causes are
- Vehicle speed circuit is open or shorted between instrument cluster and ECM.
- Defective instrument cluster.
- Defective vehicle speed sensor.
- Defective ECM.
Diagnostic Aids
Using Toyota hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.