Troubleshooting a Wiring Harness That is Not Getting Power on a 2019 VW Golf  

Question:

Expert Reply:

This does happen sometimes when installing wiring harnesses and is usually caused by one of three things. You will need to use a circuit tester, like the # PTW2993, to figure out which will be the cause.

First, and the easiest, will be to check the fuse in line from the battery to the ModuLite box. These are occasionally bad out of the box and will not allow any power to get where it needs to go. If it is indeed bad, replace it and test your 4 Flat. You should be good to go, but if you still are not getting power, move on to the next step.

Second, you will need to test the long black wire directly before it was spliced to the black wire on the ModuLite box. If you are not getting power, you will need to replace the battery wire with # 118151. If you are getting power, test the short black wire going into the ModuLite box directly after it was spliced to the longer wire. If you are not getting power, odds are you will just need to cut the splice off and use a butt connector like the # DW05745-5 to get a more solid connection.

Once all that is tested and you confirm there is power going into the ModuLite box, test all the wires to see if they are working. If you still are not getting anything, check to make sure your ground has a good solid connection to bare metal. It is always best to have this as its own location and not stacked with other ground sources.

If this is all good, you will need to replace the harness, unfortunately.

expert reply by: Lazer S

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