Fuel pump kill switch

[coopman]

Apologies for starting a new thread for a topic that's been discussed a bunch of times before, but I'm struggling with this one - either because I'm blind, or a moron. I've just installed a Rightclick remote locking unit, so thought I'd put in a kill switch whilst I have easy access under the dash. I'm following Brian's instructions:

Take an E30 panel switch, such as a demister one, connect one wire from it to the green/purple wire to the fuel pump where it goes down past LH front speaker (tee into it, not cut it) and connect the other wire to the main earthing stud behind the gearbox. You can also arrange for the internal lamp in the switch to light when the ignition is on as a reminder, but it may just alert a potential thief as well.
Fit the switch in one of the spare locations in the dash.
Leave the switch turned on when you park the car.

The problem is that I can only find one green/purple wire in the area around the LH speaker, and it's taped up with the speaker wires and capped?? From what I read, the fuel pump wire on E30s is always green/purple - but could it be a different colour for any reason? Is there any other way of identifying the correct wire other than checking the source? Does anyone have any pictures?

As a bonus stupid question, when you tee-into a wire what's the best way to insulate the connection - heat shrink?

[rix313]

When you say it's capped... is it a DIY cap? I assume you have looked for the other end of said capped wire? Is it possible someone else has attempted this and lashed some wiring in? With 30 year old cars there'll always have been someone with a bright idea and no skill attempting something and making a pigs ear of it.

[biffer]

When i did this mod i found two purple/green wires in that area- the wrong one was the same thickness as those around it, but the fuel-pump wire was noticeably fatter than its neighbours, and was buried in the vertical loom that runs next to the speaker

[Brianmoooore]

Second green/purple you found is probably an unlock request wire from the central locking. Should be a thinner wire than the fuel pump feed.
To tee into the wire and insulate with heat shrink you'll have to cut the original wire to get the sleeving on, then solder all three ends together. In this case, where the joint is to be buried in a loom, it's better to just strip off 10mm of insulation on the original wire, wrap the end of the new wire around it, solder, insulate with PVC electrical tape, then rewrap the whole section of the loom with loom tape. The PVC tape won't be able to come loose when wrapped into the loom.

[coopman]

Thanks guys, I'll have a closer look. And thanks Brian, I thought electrical tape was a bit of a bodge, but it makes sense here.

[coopman]

Found it, job done. It was a case of blindness.