Forum » Professional Motorsport Wiring Harness Construction » Back Pinning and Fault Diagnosis

Back Pinning and Fault Diagnosis

Professional Motorsport Wiring Harness Construction

Discussion and questions related to the course Professional Motorsport Wiring Harness Construction

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My original intention was to build a quality harness for the entirety of my rally car. I wired it from scratch when I built the car but the quality is very questionable! Having watched some of the pro wiring course I think I may have tried to bite off more than I can chew/afford.

Anyway, my question is this. Once a motorsport wiring harness is built with lovely heat shrink, sealing and booting how do you go about back pinning components or connectors when fault finding? I assume it is a case of pulling boots off which then ruins all the hard work. I realise that the idea of a quality pro harness is that it will not have issues but components fail and gremlins often appear.

I did not buy the clubman course but some of the pictures relating to that course weem to show that connectors are not booted hence back pinning is possible. Am I right? This obviously then leaves the issue of strain on the wires.

It’s the same issue I had earlier. I was thinking of making kind of adapter To fit it between the connectors I want to diagnose I know it’s not the best idea.

If you need to cut a boot off, you cut the boot off, and put a new one on when you're done.

Generally debugging is done with software in the ECU / Logger. If you need to look at a signal often, you might make an break-out adapter as suggested above.

If you're building a one-off motorsports harness -- don't put boots on a connector until you've verified everything connected through it is functional. That's the point you might be back-pinning a connector.

Strain Releif on wires is taken care of in installation (wire ties upstream of a connector). Motorsport wiring is often installed / removed many times, so we like to build the strain relief into the harness.

Using a breakout box is probably the best option. Also, if you are using common connectors in your harnesses (DTM series, Deutsch AS, etc...) you can use the same box for various system, so it can be a good investment.

OK, that all makes sense