Dashboard - Part 1 - Wiring Loom

Here is another note from Phil, who has been working on the wiring for the Pop for us....really appreciated Phil!

I am sure you will agree when you read this, Phil is the right man for the job! Anyway over to you Phil.

Notwithstanding the other jobs, part of the pre-Beach Hop tidy up plan for the Pop was to fit or replace:

·      instruments

·      electric radiator fan

·      LED tail lights

·      stereo

·       keyless (starter button) operation

Colin was intending to just splice into the existing loom, but experience has taught me that, when it comes to messing with bird’s nests of wiring like the Pop currently has, it rapidly gets to the point where it is actually quicker and easier to start again and produce an all new loom. 

See what I mean!

Furthermore it is safer as you can ensure all the wiring is of suitable gauge for the current draw, and is fused and routed correctly.

Given how fastidious Colin is with his cars, I also knew he wouldn’t really be happy with the way the current (OK, bad pun...) wiring is all exposed/hanging out under the dash.

Colin has enough on his plate as it is with the steering and other pre- Beach Hop  tidy up work, and I wanted to help. I figured the wiring is something I can (and want to) do to contribute.

The majority of the wiring I have done is EFI engine swaps, and despite losing count I reckon I have done over 50 of them. I have also wired about 10 vehicles from scratch, including Lotus 7 replicas, race and rally cars plus competition 4WDs, although I haven’t done a full car loom for a few years. As it pans out the timing is actually pretty good as I have got 3-4 car looms to do over the next year or so, and there are a lot of similarities (although all the other vehicles run EFI) with the loom I am doing for the Pop.

I prefer to wire a car by making a bespoke wiring loom – I find the generic aftermarket wiring kits just don’t suit the vehicles I tend to end up wiring, and hence would need a lot of modification and additional circuits to meet the needs. I also do not think they are all that cheap.

I am also integrating a 5-star car alarm that not only automatically immobilises the start and run circuits, but also controls the central locking that is likely to be fitted later. It makes far more sense to build the alarm into the wiring loom from the outset, as it also dictates the design of some of the circuits. 

The alarm is even more critical in this case as the car will not have a keyed ignition switch, and potentially once the central locking is fitted the car won’t have a key at all – which means that having some provision to get around a flat battery when the doors are still locked might be required!

Like most of the vehicles I have wired space in the Pop is at a premium, with my aim being to have the alarm brain, fuses and relays packed as closely together as possible. So far I have used 7 relays and 11 fuses (with at least another 6 fuses required, and probably a couple more relays too) so my aims of taking up not much more space than a piece of A5 paper are looking doomed. I still expect it to have a total footprint smaller than A4.

Given I am located in Wellington I am making the loom up with sufficiently long wiring ‘tails’ to enable the loom to be tailored to fit the car when I am up in Auckland in a week’s time. I have considered the range of circuits required and tried to make allowance for all the custom touches the wiring will need, like the ability in the future to fit say electric windows, bigger alternator, Lexus V8... (not that I am biased).

The first circuits I tackled were the ‘run’ and ‘start’ circuits, which are fairly complicated as not only do they need to incorporate the alarm immobiliser wiring, but I also had to figure out a way to have the starter button only work when the ignition is turned on. I also need to have the accessories and things like wipers drop out when the starter motor is engaged (to reduce current draw). 

The lack of a normal key switch actually complicates things quite a bit, as the alarm automatically immobilises the run circuit 30 seconds after the engine is turned off, and last thing I want to have happen is the stereo not be able to be used because the alarm has cut accessory power too. I was also mindful that to make the car more secure I needed to make sure the alarm was immobilising the actual main power feeds, not just the small current trigger circuits – and to achieve all this without using half a dozen relays in the process.

It took me 6 iterations to get the drawing right for this part of the circuit, and I found the design changed one last time as I actually started to wire it up. 

I next did the hazard lights, horn and turn signals circuit. This is also relatively complicated as the factory hazard light switch isn’t being used, plus a special LED compatible flasher unit is required so the lights don’t flash too quickly given the lower overall current draw.

The challenge here is ensuring the hazard system works whether the car is turned on or not, but that the indicators will not work if the car is turned off. This was achieved via a relay and a cunning circuit. The alarm also flashes the turn signals when it is armed/disarmed, so that circuit had to be added in too.

The headlights, wiper/washer and remaining circuits like engine, alternator and instruments are much more standard and will be best tackled when I am in Auckland.

Until then, here is what the ready to go loom looks like so far.

And here are a few of my scratchings so you can see just what is involved in sorting through it all.

Phil