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Home >> Toyota >> 2003 >> Matrix Base, FWD, Automatic >> Repair and Diagnosis >> External Pages >> Different car >> Section 15 (Engine Control System Self-Diagnostics) >> Diagnostic Tests >> DTC P1637: ESTP Signal Malfunction >> Diagnosis & Repair
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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.
  1. Remove glove box for access to ECM with electrical connectors still installed on ECM. See Figure. Start engine and allow engine to idle. Using voltmeter, check voltage between body ground and terminal No. 16 (Red/Yellow wire) at ECM electrical connector E9. See Figure. This is the ESTP terminal on ECM. Voltage should be 9-14 volts. Shut engine off. If voltage is not within specification, go to next step. If voltage is within specification, replace ECM.
  2. Check for open and short in Red/Yellow wire and electrical connectors between terminal No. 16 at ECM electrical connector E9 and terminal No. 8 at HV ECU electrical connector H14. This is the ESTP terminal 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.
  3. 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.
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