| CAUTION | If ECM replacement is instructed in following testing, always ensure ECM harness connector and ground circuit are okay. If either are suspect, 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 - LEXUS article in GENERAL INFORMATION. |
Circuit Description
When engine is being cranked, battery positive voltage is applied to terminal STA of ECM. DTC is set when vehicle speed is at greater than 12 MPH, engine speed is greater than 1,000 RPM, STA signal is on, battery voltage is 10.5 volts or more and all conditions continue for more than 20 seconds. Possible causes are
- Short in park/neutral position switch assembly circuit.
- Faulty park/neutral position switch assembly.
- Faulty ignition switch.
- Faulty ECM.
Diagnostic Aids
Read freeze frame data using hand-held tester or OBD-II scan tool, as freeze frame data records engine conditions when a malfunction is detected. When troubleshooting, it is useful to determine whether vehicle was running or stopped, engine was warmed up or not, air-fuel ratio was lean or rich, etc. at time of malfunction.