Full Electrical System Replacement

[Skifledanabit]

I\'ve always been the kind of guy who has no idea about the electrical system in a car, I\'m ok with the engine and moving parts, I can scrape by on bodywork etc, but the electrical system just baffles me, I\'m the kind of guy that likes anything that confuses me to be new... so, does anyone know what a full electrical re-wiring would cost, where it can be done, would it be worth it (maybe even to upgrade with better wires) and if not the entire system, which bits would be best to concentrate on?
 
Any other responses would be appreciated.

[Prof]

You can get the loom pieces seperately - the ones that are most worth replacing :
 
1) Wiring loom from Main Fuse box via lights and front relays that goes to the switches on the cluster. This is the main lights loom - because it runs in front of the rad, it gets water in it and rots big time. Most of the problems with lights not popping up/down, or coming on dim, or not working are usually down to a fault in this loom
 
2) Engine loom - this one gets oil / fuel fumes / heat and water (dripping in through bonnet) - it goes hard and brittle - and then you get shorts or open circuit. This loom is key as it carries the sensor signals, solenoid drives and injector drive from the ECU - well worth replacing this when you have the engine out ! I will next time.
 
3) Most of the other loom runs go down both sides of the car towards the rear - they usually fair a lot better as they are inside the car, but if you\'ve got rust / water leaking in - then these are worth looking at.
 
4) Door looms - not much to say really - a few buttons, the speakers and so on - could be worth looking at if you\'ve got problems with locks / windows.

[Skifledanabit]

do we have prices on these different looms (and maybe a guide on how to do it...?)

[pdtaylor18]

Just one question....Why??
I have reloomed a cab (my white one) as it was converted from from a S4 to S5. Having looked at the loom in vast detail (the entire loom from boot to engine) the main bits that fall foul of corrosion/damage are:

1. Door loom connectors just inside the upper side footwells
2. Fuse box area can be a bit of a mess if someone has hacked into it for alarms and other add on bits.
3. The biggest culprit is the engine loom but then mostly down to the injector cables and some of the emissions but most people do away with that anyway so you can cut those wires out.
4. Fuel pump cable,not that there has been anything wrong with the ones I have had but more for future proofing and reliability.

The only reason this would be worth doing is to get rid of weight if this is your drift or track car and then you can get rid of a lot of cables. If this is a road car and going to be kept as it is then to be honest just check the connectors,clean and then leave it like that. The engine bay is where you want to look,especially on top of the engine. The Earth points are also worth a check,clean and new bolts etc used. I run a seperate earth for the ECU to ground and also run a seperate earth from engine to ground,even my exhaust is grounded.

[Skifledanabit]

well, it is just for peace of mind tbh, my headlights have been playing up and I\'ve tried looking for the earth but cant find it anywhere near the battery box, the negative cable runs out alongside the live cables and I lose it near the inner arch\'s widest point, runs under and brace for something and cant find it again... if anyone can get a picture of where its supposed to be...?

[pdtaylor18]

There are two earths for that loom, one is just down by the coil pack by the battery, the other is the other side by the fuel pump relay. I will get you a pic later,raining at the mo.
It could also be your headlight connectors as they do get a soaking from water dripping of the bonnet and into the bay,they are also in each of those corners,might be worth seeing what they are like.
If and when you strip the car down you will find that 99.5% of the wiring is infact very good, I would just concentrate and the known troublesome areas,replace connectors if you have to etc.