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.
DTC C1521 Motor Relay: Wiring Diagram
Vehicle dynamics control system < Ref. to appropriate wiring diagram in SYSTEM WIRING DIAGRAM article. >
| Step | Check | Yes | No |
|---|---|---|---|
1 CHECK VDCCM & H/U INPUT VOLTAGE.
|
Is the voltage 10 - 15 V? | Go to step 2 . | Repair the VDCCM & H/U power supply circuit. |
| 2 CHECK VDCCM & H/U INPUT VOLTAGE. Calculate the voltage difference measured in step 1.
|
Is the voltage difference between A and B 2 V or more? | Repair the power supply circuit. | Go to step 3 . |
| 3 CHECK INSTALLATION OF VDCCM & H/U GROUND. | Is the VDCCM & H/U ground terminal installation bolt installed correctly? | Go to step 4 . | Install the VDCCM & H/U ground terminal installation bolt correctly. |
4 CHECK VDCCM & H/U GROUND CIRCUIT (CHECK FOR OPEN CIRCUIT).
|
Is the resistance less than 10 Ω? | Go to step 5 . | Repair the VDCCM & H/U ground harness. |
| 5 CHECK VDCCM & H/U MOTOR RELAY. Measure the resistance between VDCCM & H/U terminals. Terminals No. 33 - No. 46: |
Is the resistance 1 MΩ or more? | Go to step 6 . | Replace the VDCCM & H/U. < Ref. to VDC CONTROL MODULE AND HYDRAULIC CONTROL UNIT (VDCCM & H/U) . > |
| 6 CHECK POOR CONTACT OF CONNECTORS. Turn the ignition switch to OFF. |
Is there poor contact of connector between generator, battery and VDCCM & H/U? | Repair the connector. | Go to step 7 . |
7 CHECK VDCCM & H/U.
|
Is the same DTC displayed? | Replace the VDCCM & H/U. < Ref. to VDC CONTROL MODULE AND HYDRAULIC CONTROL UNIT (VDCCM & H/U) . > | Go to step 8 . |
| 8 CHECK DETECTION OF OTHER DTCS FOR VDC. < Ref. to READ DIAGNOSTIC TROUBLE CODE (DTC) . > |
Is any other DTC displayed? | Perform the diagnosis according to DTC. < Ref. to LIST OF DIAGNOSTIC TROUBLE CODE (DTC) . > | Currently, it is normal. There may have been a poor contact in the harness and connector or a temporarily noise interference.
NOTE:
Though the ABS warning light, and the VDC warning light & VDC indicator light may remain lit at this point, this is normal. Drive the vehicle at 40 km/h (25 MPH) or more in order to turn off the ABS warning light, and the VDC warning light & VDC indicator light. Be sure to drive the vehicle and check that the warning light goes off.
|
NO RELATED
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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.