Don't cut the wrong harness when replacing glow plug harness!


Well-known member
Feb 20, 2011
14 Q5
My glow plug harness was missing a few insulators so I started to replace it tonight. I found the harness plug conveniently located next to the battery. Or so I thought. I cut off the connector and old harness, put everything back together and started the car. I immediately got a battery light and eventually fault codes for glow plugs, all four of them. After I thought about what I've done and some research on the board, I found the correct harness and repaired the one I cut. I wanted to post this in case someone else does the same thing. Here's what I've learned;
1. The Germans should stick to mechanical design and stay away from electronics. The Japanese would never have the same two connectors in a car, much less in the same general area. Google "poka-yoke" and you'll see what I mean.
2. I should stick to mechanical repairs, not electrical
3. Always search the board first before even making the seemingly easiest repairs!


Certified Volkswagen Nut
Jul 10, 2006
spiral arm, milky way (aka central NC)
Tacoma 4x4 converted to TDI
point 3. agree completely!! if you started with that the first two would have been moot points ;).... glad you got it sorted though and no permanent damage done ... as for germans using the same connectors in various places throughout the harness i kinda like it as it gives more options when looking for repair connectors :)