Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSTOYOTA2004MATRIX XR, FWD, STANDARDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 203 (POWER SEATS)SYSTEM TESTSTEST NO. 11: MEMORY FUNCTION DOES NOT OPERATE
2004 Toyota Matrix XR, FWD, Standard
Test No. 11: Memory Function Does Not Operate
2004 Toyota Matrix XR, FWD, StandardSECTION Test No. 11: Memory Function Does Not Operate
WARNING: This page is about a different car, the 2002 Toyota Avalon. However, it is still accessible from the selected car via links, so may be relevant.
- Turn ignition off. Remove power seat ECU with connectors still attached. See Figure. Using a DVOM, backprobe harness side of power seat ECU 25-pin electrical harness connector P21 with negative DVOM lead on terminal No. 19 (Brown wire) and positive DVOM lead on specified terminals of ECU 25-pin electrical harness connector P21. See Figure. See DRIVING POSITION MEMORY SWITCH CIRCUIT TESTING CONNECTIONS table. Battery voltage should exist when ignition is off. No voltage should exist when ignition is on. If circuits test as specified, go to step 4. If circuits do not test as specified, go to next step.
- Check driving position memory switch. See DRIVING POSITION MEMORY SWITCH under COMPONENT TESTS. If driving position memory switch is okay, go to next step.
- Disconnect 25-pin electrical harness connector P21 from power seat ECU. Disconnect 4-pin electrical harness connector from driving position memory switch. Using an ohmmeter, check for opens and shorts in wiring harnesses and electrical connectors between power seat ECU and driving position memory switch. See MEMORY SYSTEMS in SYSTEM WIRING DIAGRAMS article. If wires, wiring harness and connectors are okay, go to step 6. If wires, wiring harness and connectors are not okay, repair and/or replace as required. After repairs have been made, perform confirmation test. See CONFIRMATION TEST .
- Turn ignition off. Remove power seat ECU with connectors still attached. See Figure. Using a DVOM, backprobe harness side of power seat ECU 25-pin electrical harness connector P21 with negative DVOM lead on good body ground point and positive DVOM lead on power seat ECU 25-pin electrical harness connector P21 terminal No. 13 (Red/Black wire). With ignition off, no voltage should exist. With ignition on, battery voltage should exist. If voltage is as specified, go to step 6. If voltage is not as specified, go to next step.
- Check GAUGE NO. 1 (10-amp) fuse located in driver side junction block. See Figure. If fuse is okay, go to next step. If fuse is not okay, replace fuse and repair circuit as required. If fuse is okay, check wiring harness and connectors between power seat ECU and battery and repair as necessary. See MEMORY SYSTEMS in SYSTEM WIRING DIAGRAMS article. After repairs have been made, perform confirmation test. See CONFIRMATION TEST .
- Check power seat ECU ground circuits. If ground circuit resistance is greater than one ohm, repair or replace ground circuit. If ground circuit is okay, substitute original power seat ECU with a known-good unit and recheck manual switch operation of power seat system. If manual switch operation of power seat system operates properly, original power seat ECU was defective. If manual switch operation of power seat system still does not operate properly, perform power seat ECU pin voltage check. See PIN VOLTAGE TESTS . Check wiring harness and electrical connectors for an intermittent problem. Repair wiring harnesses or connectors as necessary. If voltage values, harnesses and connectors are okay, replace power seat ECU. After repairs have been made, perform confirmation test. See CONFIRMATION TEST .
DRIVING POSITION MEMORY SWITCH CIRCUIT TESTING CONNECTIONS
| Positive DVOM Lead At Terminal No. (Wire Color) (1) | Negative DVOM Lead At Terminal No. (Wire Color) (1) | ||
|---|---|---|---|
| 9 (Green/Yellow) | 19 (Brown) | ||
| 20 (Yellow) | 19 (Brown) | ||
| 21 (Green/Red) | 19 (Brown) | ||
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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.