Recurring X-relief circuitry problem

[Roger Blassberg 0]

This seems to happen only in warm weather or when re-starting a hot engine.

 

The X-relief circuits (heater blower, windscreen wipers, ABS, headlights) sometimes, not always, remain isolated once the car has started and remain so for quite a while (many minutes). The problem can be temporarily fixed by switching on headlights and wipers and indicators and headlight flashers all at once for about half a minute.

 

I have changed the x-relief relay.Not a solution.

 

I noticed this problem first when I installed a relayed dipped headlight wiring loom.

 

Any clever auto-electricians out there who can help, please. Have I upset things by changing the resistance of the headlight circuit through the switch as the circuit now only switches the relay rather than the full headlight load? I also disconnected the dim/dip resistor, the yellow plug in front of the battery.

 

All comments greatly appreciated.

 

RB

[Supercharged 2]

You can also unplug the dim-dip at the fusebox end - look at the loom to the headlight switch.

 

Maybe remove / disconnect the uprated loom or headlights to test next time it occurs?

[Roger Blassberg 0]

To resurrect this.

I now have the situation where when switching to main beam or using the headlight flasher, ONLY offside headlight works. Nearside does not illuminate either inner or outer lamp. And the blue main beam warning light does not come on.

 

All fuses are present and correct. I have swapped back to the original headlight switch, having been using one of the "new improved" ones from here. The bulbs themselves are ok. The wiring to the main beam circuit is NOT via a relayed loom but is the original. Looks like a bad main beam wire on one side.

Dipped beam works on both sides.

 

Comments please.

[Henny 0]

I think it may be time to break out the multi-meter and find out what's actually happening on the wires when the switches are in each position at both ends of each wire...

 

To be honest, as soon as I saw X-Relay problems, and that you'd changed the relay, my first thought was "ignition switch"... I know you've been around the forum long enough to know what a PITA they are, and symptoms like those you describe in the first post can be as a result of back-feeding circuits enough to allow stuff to start working until the ignition switch finally allows the X-relay to fire as it should... For the price, I'd be seriously thinking about replacing the ignition switch, so at least you can rule it out of the equation... :)

 

Good luck!

[Supercharged 2]

I think you're right with a bad main beam connection - you can test further but trying each plug individually and also swapping the headlamps from side to side to test.. as Henny says, get the multmeter out and you'll find the issue!

[Roger Blassberg 0]

Thanks Henny and Supercharged. I have looked at the wiring diagrams in Bentley ( up until the wee small hours) and it looks fairly straightforward. Famous last words.

 

The one-on one-off problem is probably either a dodgy feed to the headlight unit, or perhaps the internal wiring in the headlight itself, from the plug/socket to the bulbholder.

 

And yes, time to change the ignition switch in the hope of banishing x-relief misery.

 

Best wishes

 

RB

[Supercharged 2]

I doubt this is anything to do with the X-relief... test each Headlight by swapping side to side then it's a case of just checking for 12V on the headlight plug connectors with the beams on

[Roger Blassberg 0]

Oh !! The embarrassment!!! It turned out to be the Nr. 11 fuse. I had visually inspected it and it LOOKED ok to the Mk.1 eyeball, but on replacing it everything came back to life. It had gone awol within the plastic case of the fuse, not an obvious burn-out rather maybe old age/corrosion.

 

I'll wait to see if this was an intermittent fault giving the X-relief the runaround. So far so good.

 

Moral; always do a proper electrical continuity check on blade fuses - they can be bad even if they look good.

 

Thanks to all who got involved.

 

RB

[Supercharged 2]

Glad you sorted it Roger!

 

Was it a non-original fuse? - had a few or these melting / going bad with age etc

 

If you can get a load of VW ones next time you're at the dealer or scrap yard.

[Henny 0]

Glad you got it sorted... :) It's nice when it's something as simple as that, even if there it does initially make you feel a little embarrassed! ;)

[Sean_Jaymo 0]

I've been bitten by that fault before! I was having trouble getting the radio to come on and was minutes from buying a new one when I con tested the fuse! 5p fuse changed, £200 saved!

[sparks 0]

whats the x relay ive never heard of it and whats its job ????

[Roger Blassberg 0]

X-relief relay cuts out various heavy demand circuits such as headlights, wipers, heater blower, indicators, abs, when cranking the engine to give maximum current to the starter motor. Nr 18 relay, position 4 on the relay/fuse board.

 

For information, I have now deleted the non-standard headlight relay and loom in the hope that this will get rid of the problem originally described. Out of interest I checked the voltage at the headlights with and without the direct feed. 14.24V against 13.87V, representing a 5% reduction in power (proportional to square of voltage). Not sure how actual light energy relates to the power reaching the bulbs, but the Osram Nightbreaker Plus bulbs are certainly much better than the original specification and I'll live with the slight reduction for the time being.

 

Best wishes and thanks for all contributions

 

RB

[Roger Blassberg 0]

One month later and the problem has gone away, so the relayed direct feed was doing something to the load reduction circuitry (home made loom, but, in all modesty, a proper job.....).

 

RB