I’ve picked up some gauges for my bus but I’m unsure what cables I need to run to the engine bay also what’s the best route to do so ? Do I run a multi core if so what size and how many would it be worth putting extra in for any further additions or should I run individual cables ? I have oil pressure, oil temp, and volts also what is the relay for and do I still need it many thanks in advance.
I made up a loom for additional gauges from the engine bay to behind the dash and ran it alongside the existing loom. As you only have oil pressure and temperature you’ll only need two cables from the engine. The same cross section cable as you have on the gauges will be fine and you don’t need the relay.
I woulf put in a reasonably heavy multicore cable of some kind. Then if you want rear fog light or something like that you dont have to run another wire just use another core. Trailer wiring would do maybe a bit large diameter. Run it alongside the main wiring harness tube. Use cable ties. Using a heavy cable means it is more robust. Drill a hole beside the main harness and use a grommet into the engine bay. You need to start with two cores for pressure and temperature. The volt metwr feed can come off the ignition switched wiring under the dash being neither the battery voltage nor the voltage on the top of the ignition coil but somewhere in between. Put a fuse in the volt meter connection at the "hot" end or use a fused circuit to feed it. The big wire from the ignition switch doesnt have any fuses so shorting out the voltmeter wire is dodgy. And please make sure you have the matching senders for the oil pressure and temperature gauges. Do not proceed until you have the correct parts as otherwise you will be amongst those who think their temperature gauge is way off.. if you match the gauge and sender it should be within 5 deg C for instance. If not correct its 20 or 30 degrees adrift... The relay looks like something to do with indicators or trailer socket.. according to this http://www.type2.com/library/identifi/bosterm.htm
Volt meter doesn't need to go to engine, just to fused ignition from fuse box. Same ignition feed will supply feed to other gauges, so only need two wires to engine switches/ senders. Relay may be lights on buzzer , if so ignore. If going to the trouble of running wires I would run a couple more.
I did think that running a few extra would be a good idea so will probably do that now @mikedjames has got me on another question how do I know that the gauges and senders are matched ? Do I need new and buy as a pair or just need to be same make or is there some super secret fandangled way to work it out lol.
They look like VDOs from an older Golf or Audi. More recent VDO senders for oil pressure and temp are likely to work, but you could check in the VDO specs which are online somewhere. As above, the voltmeter just connects to a switched +12 from the ignition under the dash. Don't expect it to be particularly accurate, especially if your main feed back to front of the van is getting a bit old. You can adjust the reading through a hole in the side. The "relay" is a slave light dimmer for the gauge illumination, so the main dimmer isn't overloaded. Should be wired to the gauge lights. If you connect the free wire to the existing (red/grey? - terminal 58) cable to the dash lights, the gauge lights should go up and down in brightness with the rest.
I woulfput in a reasonably heavy multicore cable ofsome kind. Then if you want rear fog light or something like that you dont have to run another wire justuseanother core. Trailer wiring would do maybe abit large diameter. Good advice Mike I am considering a rear fog plus a couple of gauges
With hindsight I'd have fitted 7 core trailer cable from the engine compartment to under the dash. It would have saved so much time fitting new cable with each "accessory ".
