Is it safe to cut or solder wires in a modern car?

[Hercule Holmes]

I'd like to fit a reversing sensor or reversing camera kit to a 2010 Volvo estate car, but watching a couple of "how to" videos on YouTube I see that the kits require wiring to the reversing light. The sensor kit is simpler, but the kits come with a T connector, which some commenters say are terrible and should never be used, and instead the job should be done properly by soldering and shrink-wrapping the joint.

I am aware that soldered joints can break and should be done using a "western union" (twist-together) joint, but one guy who claims to have been doing wiring for 25 years is saying that if I cut the wire, the car could need a new wiring loom. Is there an FAQ somewhere about this? I can solder very well, but I do not know enough about cars to take the risk of doing something stupid.

[Oldandslow]

Um. I've wired in a few things. Never needed a new loom. He may mean you need to disconnect the battery or you might damage something and ensure you don't accidentally short it to ground. Could be a warranty concern. Actually just read his posts, not sure why Mercedes are specifically allergic to solder but he seems very worked up about it.

The quick snap type (Scotch lock) connectors are a bit iffy, especially where they might get wet. I've bodged a few radios with them for convenience under dash boards but for anything engine bay/exterior I crimp or solder. No Mercedes though.

Edited by Oldandslow on Friday 17th May 11:17

[PositronicRay]

I'd use crimp connectors, shrink fit waterproof ones are available for vulnerable areas.

[finishing touch]

Have a look at where you would replace the reversing light bulb and you may find that there are additional spade connector points on the light unit board.
They are for use when fitting a tow bar.

Tow bar wires on my Passat Estate.

HTH
Paul G

Edited by finishing touch on Friday 17th May 12:27

[E-bmw]

As above look for a better place in case one exists but, in answer to your question, yes it is fine.

[Dave.]

Just don't cut into any old wire without checking what it is, where it does to and what juice it's carrying, as you don't want to be cutting into any canbus wires.

[Hercule Holmes]

Thankyou for the wiring tips. I can't see why anything would go wrong (I shall take care to identify any CAN bus wires) but better to be safe than sorry.

[Sheepshanks]

I can only guess the concern is about shock, vibration, corrosion etc which can happen with solder joints but that's more something that would be of concern in a military etc application.

[GreenV8S]

There are pros and cons to soldering versus crimping, but they are both infinitely preferable to those nasty insulation displacement splice connectors.

[RLK500]

I just repaired the rear parking sensor wiring on my (2009) Mondeo. I re-soldered the broken wires, it was a bit fiddly as not exactly lots of free wire to play with, but soldered fine and they now work perfectly again. No subsequent issues at all.

[Krikkit]

I prefer to crimp wiring because it's easier to perform in awkward spots, it's also easier to trace out later.