I know the fuses are behind the glove box, but where are the relays, specifically the fuel pump relay?

 

I'm thinking of adding a kill-switch to the car and this is an ideal location to tap into (like this vid: https://www.youtube.com/watch?v=XUhXLsrZiE0).  My last car was stolen in March and a couple lads were spotted on my CCTV at 2:30am the night before last poking around the front of my house, so I'm fearing they might be after the VRS (despite choosing it as hopefully less desirable to steal than my last car...)

 

I've found a few fuse diagrams and some relay info for the mk2 Octavia, but I've not seen anything for the mk3.  The closest I can see from the fuse diagram in the manual is a fuse in the engine bay fuse-box, but I'm ideally trying to avoid running a wire through the firewall.

 

Cheers for any help/ideas

Edited 9 July, 20196 yr by DereksDontRun

Engine code is required in order to make any useful inroads into wiring diagrams. If you can tell me that, I can have  a look.

erm, which engine code?  it's a 66 plate 2.0 VRS petrol 230 (pre fl), I think that's CHHA?

There isn't a relay as such for the fuel pump, there's a 'fuel pump control unit, J538'. Appears to be cabin located, probably adjacent to the tank. Interrupting either the feed - red/blue wire, or earth - brown wire, with a switch might accomplish what you want. Will probably log all manner of errors if you try to start the car without flipping your switch though.

May even cause problems anyway, as the car may try to establish fuel pressure in the engine bay when the driver's door is opened, before you even get to the switch?

 

Not sure this is the best approach to security, if I'm honest.

Edited 9 July, 20196 yr by Wino

cheers for the reply.

 

hmm..  Good point about the fuel pump potentially priming before even getting the key into the ignition...  If that's the case, then presumbaly switching it on after getting into the car wouldn't help, as the ecu has already tried (and failed) the pump and is left sat there.  Would have to lock and unlock the car again???

 

If it's a fuel pump control unit by the fuel tank, then surely there's a fuse to isolate it?

 

I recently helped build a Westfield, where the fuel pump primed on the 1st click of the ignition, so thought it would be the same here - but, I understand there's no guarantees at all.  I guess I can use multimeter on the wiring and find out, if I can get to it?!?

 

Yeah, I'm fully expecting some error codes if the car is attempted to be started without the switch being toggled, but I can't see a way around that.

 

Would running a switch in line with the ignition fuse be a better idea then?

 

 

Fuse 10 in the engine bay fuse box, I think, feeds J538.

The pump probably will try to prime again when ignition is switched on, so it may not be a problem?

 

There is a relay that switches the power feed to the ignition coils for start/stop purposes (I think). So called 'Ignition off relay' J240, in engine bay e-box thing. Interrupting feed/earth or either of the coil wires could be done, but would require wiring through to cabin.