A Volkswagen Touareg 2004 year with 3.2L V6 engine, with 180 thousand KM, owner said the airbag (SRS) light on.
I connect X431 to read the trouble code, and the fault code is 00592, it show that the right seat belt switch has fault. And the driver said, he used to repair and change the passenger seat belt, but the fault stays. Based on the current fault and the previous diagnostic history, I doubt there are 3 possible reasons:
- Launch X431 is not professional VW diagnostic tool; maybe it had an incorrect diagnosis.
- the new seat belt has poor quality;
- the seat belt harness or airbag control unit has fault.
Firstly, judge whether X431 had a fault diagnosis: to unplug the passenger seat belt switch plug and airbag ignition plug, X431 displays the fault is corresponding to the unplugged plug, it means X431 is right. Next is to check the new seat belt, I apply the way that measure the resistance of seat belt switch, the resistance value is infinity when seat belt switch is unplugged, and 0Ω when seat belt switch is plugged, by this way, I know how the new seat belt works, the measuring result indicates the new safe bel has no quality problem. Then I also use the same way to measure the original seat belt, the resistance value is 400Ω when seat belt switch is unplugged, and 300Ω when seat belt switch is plugged, the comparison result tell me the original seat belt switch and the new one have different working principle, although the new seat belt switch quality is not poor, it isn’t compatible with the original car. I go on carefully check the new and original seat belt Part Number, I find the new seat belt Part Number is 716857 778 E, and the original one is 716 857778 B. Then what cause the original seat belt has fault and couldn’t be cleared? To confirm whether seat belt switch resistance value is 400Ω and 300Ω, I measure driver s seat belt switch resistance value, the result is the resistance value is 400Ω when driver s seat belt switch is unplugged, and 99Ω when plugged. This means passenger seat belt switch working resistance is abnormal which cause the trouble code, I guess the possible reason is the contacts in the switch has poor contacting and lead to abnormal resistance value.
Solution: I changed the same model seat belt and the fault is troubleshot.