Home/Toyota/MR2/Toyota MR2 W30 (1999-2007)/Repair manual/Testing & Diagnostics/DTC P1646: TRANSMISSION CONTROL ECU MALFUNCTION
Contents Wiring diagrams Section: Testing & Diagnostics All sections

DTC P1646: TRANSMISSION CONTROL ECU MALFUNCTION Toyota MR2 W30

Note. DTC applies to models with sequential manual transaxle. Sequential manual transaxle is an electronically controlled manual transaxle in which the clutch is operated and transaxle is shifted hydraulically by moving the shift lever forward or backward. Sequential manual transaxle may be identified by shift lever pattern which consists of "R", "N", "S" and "+" in place of the conventional type shift lever pattern and no clutch pedal is used.

CAUTIONIf 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 - TOYOTA article in GENERAL INFORMATION, or appropriate ENGINE IMMOBILIZER SYSTEMS article in ACCESSORIES & EQUIPMENT.

Circuit Description

The transmission control ECU communicates whether its operation is normal or not to the ECM using this line. When the transmission control ECU is operating normally, it sends a constant pulse signal to the ECM.