Diagnosis & Repair
WARNING: This page is about a different car, the 2002 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.
- Remove glove box for access to ECM with electrical connectors still installed on ECM. See Figure. Connect negative lead of oscilloscope to terminal No. 18 (Brown wire) and positive lead to terminal No. 19 (Yellow wire) at ECM electrical connector E9. See Figure. This is the HTE - and HTE+ terminals on ECM.
- Turn ignition on and note voltage waveform pattern on oscilloscope. Ensure voltage waveform pattern is as shown in illustration. See Fig 1. If voltage waveform pattern is not as shown, turn ignition off. Go to next step. If voltage waveform pattern is as shown, turn ignition off. Replace ECM.
- Check for open and short in Brown and Yellow wires and electrical connectors between terminals No. 18 and No. 19 at ECM electrical connector E9 and terminals No. 19 and No. 29 at HV ECU electrical connector H14. This is the HTE - and HTE+ terminals on ECM. For HV ECU electrical terminal identification, see Figure. HV ECU is located below carpet on floor panel, just below passenger's side of instrument panel. See Figure.
- If wiring harness or electrical connector is defective, repair as necessary. If wiring harness and electrical connectors are okay, replace HV ECU. If HV ECU is replaced, the HV ECU must be reprogrammed for the engine immobilizer system. Engine immobilizer system may also be referred to as Hybrid Vehicle (HV) immobilizer system. For programming procedures, see HYBRID VEHICLE ELECTRONIC CONTROL UNIT PROGRAMMING under PROGRAMMING.