SYS.OK|MANUAL.DB● LIVE
HOMESERVICE MANUALSTOYOTA2004CELICA GT, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT VARIANT/TRIMSECTION 5 (ENGINE CONTROLS (2ZZ-GE) - DIAGNOSTICS)CIRCUIT INSPECTIONECM POWER SOURCE CIRCUITINSPECTION PROCEDURE
2004 Toyota Celica GT, Standard

Inspection Procedure

2004 Toyota Celica GT, StandardSECTION Inspection Procedure
WARNING: This page is about a different variant/trim than selected.
  1. Check voltage between terminals +B and E1 of ECM connector. 

    PREPARATION: 

    1. Remove the ECM cover.
    2. Turn the ignition switch ON.

    CHECK: 

    Measure voltage between terminals +B and E1 of the ECM connector.

    Fig 1: Identifying Terminals +B And E1 Of ECM Connector
    G02897952Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: 

    Voltage: 9 to 14V 

    1. OK : Replace ECM (See ENGINE CONTROL MODULE (ECM) in  SFI  ). 
    2. NG : Go to next step. 
  2. Check for open in harness and connector between terminal E1 of ECM and body ground (See  HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE  ). 
    1. NG : Repair or replace harness or connector. 
    2. OK : Go to next step. 
  3. Check voltage between terminals IGSW and E1 of ECM connector. 

    PREPARATION: 

    1. Remove the ECM cover.
    2. Turn the ignition switch ON.

    CHECK: 

    Measure voltage between terminals IGSW and E1 of the ECM connector.

    Fig 2: Identifying Terminals IGSW And E1 Of ECM Connector
    G02897953Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: 

    Voltage: 9 to 14V 

    1. OK : Go to step   5 . 
    2. NG : Go to next step. 
  4. Check ignition switch (See  INSPECTION  ). 
    1. NG : Replace ignition switch. 
    2. OK : Check and repair harness and connector between battery and ignition switch, ignition switch and ECM (See  HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE  ). 
  5. Check voltage between terminals MREL and E1 of ECM connector. 

    PREPARATION: 

    1. Remove the ECM cover.
    2. Turn the ignition switch ON.

    CHECK: 

    Measure voltage between terminals MREL and E1 of the ECM connector.

    Fig 3: Identifying Terminals MREL And E1 Of ECM Connector
    G02897954Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: 

    Voltage: 9 to 14V 

    1. OK : Replace ECM (See ENGINE CONTROL MODULE (ECM) in  SFI  ). 
    2. NG : Go to next step. 
  6. Check EFI fuse. 

    PREPARATION: 

    Remove the EFI fuse from the engine room J/B.

    Fig 4: Removing EFI Fuse From Engine Room J/B
    G02897955Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    CHECK: 

    Check continuity of EFI fuse.

    OK: 

    Continuity 

    1. NG : Check for short in all the harness and components connected to EFI fuse. 
    2. OK : Go to next step. 
  7. Check EFI No. 1 fuse. 

    PREPARATION: 

    Remove IGN fuse from engine room J/B.

    Fig 5: Removing IGN Fuse From Engine Room J/B
    G02897956Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    CHECK: 

    Check continuity of EFI No. 1 fuse.

    OK: 

    Continuity 

    1. NG : Check for short in all the harness and components connected to EFI No. 1 fuse. 
    2. OK : Go to next step. 
  8. Check EFI main relay (Marking: EFI) (See EFI MAIN RELAY in  SFI  ). 
    1. NG : Replace EFI main relay. 
    2. OK : Go to next step. 
  9. Check for open and short in harness and connector between EFI relay and ECM, EFI relay and body ground (See  HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE  ). 
    1. NG : Repair or replace harness or connector. 
    2. OK : Check and replace harness and connector between terminal +B of ECM and battery positive terminal (See  HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE  ). 
RENDER: 1.0x

NO RELATED

Recommended Tools & Savings

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Affiliate disclosure: We may earn a commission at no extra cost to you.

Shop Manual-Ready ToolsFree Quote CheckQuote Shield Pro

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.