FAULT OVERVIEWUnderstand the symptom before replacing parts
A step-by-step troubleshooting guide that checks power, wiring, settings, and the affected component before parts are replaced.
English tutorial overview Complete English infographic with the six diagnostic or repair steps shown below.TOOLSPrepare before testing
- Digital multimeter
- Suitable inspection tool
- Fuse tap
- Correct-rated fuse
- Suitable inspection tools
!Safety noteUse the product label and wiring diagram as the final authority.
COMMON CAUSESCheck these areas first
- Power or voltage mismatch
- Loose, reversed, or damaged connection
- Controller, driver, or component failure
- Incorrect setting or incompatible device
STEP BY STEPDiagnostic procedure
Follow the sequence and change only one condition at a time.
01
Disconnect power and inspect the installation
Check the fuse tap, ACC source, ground point, controller, and branch connectors for looseness or damage.
Step 01: Disconnect power and inspect the installation — Cropped directly from this tutorial’s English main infographic.What to observeRecord the reading or behavior before changing the next variable.
02
Measure supply voltage in each vehicle state
Compare voltage with ignition off, ACC on, cranking, and engine running.
Step 02: Measure supply voltage in each vehicle state — Cropped directly from this tutorial’s English main infographic.What to observeRecord the reading or behavior before changing the next variable.
03
Compare a working branch with the faulty branch
Swap only one branch or controller output at a time to isolate the problem.
Step 03: Compare a working branch with the faulty branch — Cropped directly from this tutorial’s English main infographic.What to observeRecord the reading or behavior before changing the next variable.
04
Inspect door-jamb and moving wiring
Look for pinched, stretched, or broken conductors near hinges and rubber boots.
Step 04: Inspect door-jamb and moving wiring — Cropped directly from this tutorial’s English main infographic.What to observeRecord the reading or behavior before changing the next variable.
05
Check color order, polarity, and connector orientation
Use solid red, green, and blue tests and verify all connectors are inserted in the same direction.
Step 05: Check color order, polarity, and connector orientation — Cropped directly from this tutorial’s English main infographic.What to observeRecord the reading or behavior before changing the next variable.
06
Repair, protect, and retest
Restore insulation, secure the wiring away from airbags and moving parts, then repeat the test.
Step 06: Repair, protect, and retest — Cropped directly from this tutorial’s English main infographic.What to observeRecord the reading or behavior before changing the next variable.
Expected result
The fault is isolated to a power source, connection, setting, controller, driver, or light section.
If the fault remains
Stop if there is overheating, odor, damaged insulation, repeated fuse failure, or exposed mains voltage.
