I'm looking to fit a 12V socket to our car which was rebuilt to 420R spec around 2014/15 and apparently had a new 420R wiring loom and fuse box suitable for the existing Stack dash setup fitted.
The wiring diagram in Figure 215 in the Master Caterham 2015 Assembly Guide (420 main harness with Stack dash) appears to show wiring provision for a 12V power supply in the rear boot area, with wire designations B14 and PG53 powered from fuse O (10A), the bottom fuse on the board, connected to wires PG53 and N52. I assume PG is Purple/Green but don't know what colour N is?
I can't find the 12V power cable/connector in the boot of our car. Also, the fuse box layout in our car appears to match the fuse layouts listed in the 2023 Caterham owners handbook for the 420 with the 12V power supply fuse in position J rather than O. Our car has an aftermarket 15A fuse fitted in lieu of the 10A fuse listed in the owners handbook in position J. This fuse is connected to one brown and one purple wire.
Can anyone advise where I might find the 12V power supply wiring and connector? I assume I should be looking for a cable tail with one brown and one purple wire and a two pin connector. Also, is there another 420 wiring diagram available with the fuse panel layout matching that in the 2023 owners handbook?
Assume you wish to fit to the fuse block cover on the passenger bulkhead. Do you want it permanently live or switched?
I wanted mine permanent, therefore, wired direct to battery with an inline fuse.
Colours: N = Brown. Because too many colours begin with B! The full set of abbreviations.
"Standard" functions: Caterham usually adhere to the "standard" British colours for functions.
Finding them: some Sevens seem to have them installed, others don't. If you do find some spare wiring in the boot check that it is the accessory power feed and not the high-level brake light feed. The colours will distinguish them, then you can confirm this with a meter.
Installing a socket:
• Do you want it switched with the ignition or always on (as above)?
• Check the fusing as above. (I'll see if I can identify your layout tomorrow.)
• It used to be easy... fit a cigar lighter socket. But do you also want one or more USB sockets? And a digital voltmeter? If fitting USB sockets in order to charge devices I strongly recommend finding some that will give the maximum 2.1 A.
Thanks for the replies, very helpful.
I'm happy with a plain old cigar lighter socket and would prefer it to be switched live so finding the 12V power supply (if it has one) would be ideal. The car has a battery isolator switch but I can't work out from wiring diagram whether the 12V power supply is switched purely by the isolator or via the ignition switch?
Do you want the socket near the dash or in the boot?
And do you have a multimeter?
PS: Most people who use the socket to leave a charger plugged in have it permanently connected to the battery, not switched with the ignition.
I fitted this to the fuse box cover, taking the supply from the existing permanent supply serving the cigarette lighter. It has an inbuilt switch (the left hand button) so can be isolated to avoid draining the battery, although I have to leave it turned on when connecting my Ctek via the 12V port.
Also, I located the rear 12V supply cable tied under the tunnel cover, behind the handbrake and just forward of the Diff. You'll probably have to take off the cover to gain access.
See my journey to a Seven life at cat310s.wordpress.com
The one in the boot I found was under the tunnel cover about 600mm behind the gearstick tie wrapped to the chassis. 2009 SV.
Scotland North AR
Jonathan, I'd prefer it under the dash and yes I do have a multimeter. I'm only intending to use it to power a tyre inflater and charging phones and I'm happy connecting my conditioner directly to the battery.
David and Nigel, thanks for the tip on location of the 12V power cable, I'll check it out. The original owner apparently installed the 420 loom and fuse box when he rebuilt the car and replaced the 2.3 Cosworth motor and sequential box from his original kit build in 2004 with a new 2.0 Duratec and Caterham 6 speed box. So it's not an original factory spec 420 and therefore an ongoing process of working out what's actually what with the car.
Although it apparently has a 420 fuse/relay box and the fuse designations mostly match the 420 info in the 2023 Owners handbook on the Caterham website, it doesn't have the cover that factory 420s have to mount the socket/s on. But I only need a single socket (nice as the Amazon kit looks!) so I'm sure I can find somewhere else to mount it.
Just to update this thread, following a closer look, it turns out fuse J in our car feeds power to a purple/red wire. This is the wire colour shown in the wiring diagram for Ford Sigma variant cars for the 12V power socket. The original owner told me he fitted a new 420 loom when he rebuilt the car so I don't know why it doesn't have the purple/green wire that the 420 apparently has for the 12V power supply .
I also found the 12V socket supply cable and male T connector tie-wrapped to the nearside wiper drive above the fuse panel so it should be easy to connect up the 12V power socket once I get a female T connector for it.
I did lift the tunnel cover in search of the 12V socket cable but found there was a horizontally mounted aluminium plate riveted to the chassis rails from just behind the handbrake all the way back to the rear bulkhead. Not sure if this is standard?