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.
12 63 520 Replacing Main Relay
Switch off ignition.
Connect DIS Tester.
Release screws (1).
Remove electronics box cover.
Installation:
Correctly install wiring harness with grommet in electronics box cover (water tightness).
Hook cover (3) into hinges of underside of electronics box (1). Then correctly install upper stop (2) above hinges on underside of electronics box.
Arrangement:
- Main relay of Digital Motor Electronics.
- Engine fuses of Digital Motor Electronics.
Notes On Troubleshooting:
If the starter motor cranks the engine during the starting sequence but the engine fails to fire, then:
- Check engine fuses.
- If fuses are blown, replace them completely with fuse holder.
- Find out why fuses have blown.
Continue troubleshooting as per DIS instructions.
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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.