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.
Relay Control System: System Description
IPDM E/R activates the internal control circuit to perform the relay ON-OFF control according to the input signals from various sensors and the request signals received from control units via CAN communication.
| Control relay | Input/output | Transmit unit | Control part | Reference page |
|---|---|---|---|---|
| Front fog lamp relay (if equipped) | Front fog lamp request signal | BCM (CAN) | Front fog lamps (if equipped) | FRONT FOG LAMP CIRCUIT CHECK |
|
|
BCM (CAN) |
|
HEADLAMP: SYSTEM DESCRIPTION HEADLAMP (LO) CIRCUIT CHECK |
| Tail lamp relay | Position light request signal | BCM (CAN) |
|
PARKING LAMP CIRCUIT CHECK |
|
Front wiper request signal | BCM (CAN) | Front wiper motor | WIPER AND WASHER SYSTEM SYMPTOMS: SYMPTOM TABLE |
| Rear window defogger relay | Rear window defogger request signal | BCM (CAN) | Rear window defogger | REAR WINDOW DEFOGGER SYSTEM: SYSTEM DESCRIPTION |
| A/C relay | A/C request signal |
|
A/C compressor | MAGNET CLUTCH CIRCUIT CHECK |
| Starter relay | Ignition switch START signal | TCM | Starter motor | STARTING SYSTEM: SYMPTOM TABLE |
| Cooling fan relays | Cooling fan request signal | ECM (CAN) | Cooling fan relay | COOLING FAN CONTROL: DESCRIPTION |
| Heated mirror relay | Heated mirror request signal | BCM (CAN) | Door mirrors | REAR WINDOW DEFOGGER SYSTEM: SYSTEM DESCRIPTION |
| ECM relay | ECM relay control signal | ECM (CAN) | ECM relay | ENGINE CONTROL SYSTEM: SYSTEM DIAGRAM (QR25DE) or ENGINE CONTROL SYSTEM: SYSTEM DIAGRAM (VQ40DE) |
| Throttle control motor relay | Throttle control motor control signal | ECM (CAN) | Throttle control motor relay | MULTIPORT FUEL INJECTION SYSTEM: SYSTEM DESCRIPTION (QR25DE) or MULTIPORT FUEL INJECTION SYSTEM: SYSTEM DESCRIPTION (VQ40DE) |
| Fuel pump relay | Fuel pump request signal | ECM (CAN) | Fuel pump | FUEL PUMP CIRCUIT CHECK |
| Ignition relay | Ignition switch ON signal | Ignition switch | Ignition relay | IGNITION SIGNAL CIRCUIT CHECK |
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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.
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