Annoying Electrical Problem - Lights/Fans/Gauges

[debaron]

Hi all,

Got a funny electrical problem - maybe someone can point me in the right direction as I'm not good with all that stuff!

When i've got my lights on the water temp gauge reads high by 5 degs or so.

If I turn them off, water temp drops immediately by 5 degs.

Also the instrument backlights flicker in brightness

Also the heater fan speed (on full) varies between quite fast and really fast

Also when I rev the engine with the headlights on they get brighter!

Checked the earth point under the centre console - all looks fine and shiny with no corrosion.


What to do next? Is it worth checking other earths?


Cheers


Ryan

[Mark_S_24]

I'm no Auto electrician but perhaps the output from the alternator isn't being regulated properly.
I had flickery lights, and an alternator that sometimes decided, I'm not charging today!
Got it changed and boom bap it was all good again.
Might be worth getting yours tested. but earths would have been where I'd have looked first too.

mark

[TVR keith]

I'd have a look at the earth point under the radiator.
My problem was that with the headlights on the fans wouldn't kick in.
Apparently it's not necessary to do so but I removed the rad to get at it, and having done so found that the wires are really short so don't know how you would clean it all up with rad in place.
Anyway, all is fine now

[SantaPod]

yep, sounds like an earthing issue.....

[spend]

Fans+lights at front chassis ground, otter+temp gauge via engine ground, heater blower at front chassis ground. I don't see any correlation with grounds and OP's symptoms, whereas the first reply regarding alt regulation seems more plausible in view of the report?

[debaron]

had a look at the battery today - was trying to put a voltmeter across it to measure voltage out from alternator and noticed a lot of white powder around the positive terminal!

Going to get it cleaned up as I think this could well be the issue.

Figuring that if the battery has poor connection to the rest of the electronics - then the system will be pulling all its power from the alternator.....is that about right?

Edited by debaron on Tuesday 25th January 14:55

[nawarne]

TVR keith said:

I'd have a look at the earth point under the radiator.
My problem was that with the headlights on the fans wouldn't kick in.
Apparently it's not necessary to do so but I removed the rad to get at it, and having done so found that the wires are really short so don't know how you would clean it all up with rad in place.
Anyway, all is fine now

^^^^^What he said.
Almost certain :-), that it's this earth point that is giving the symptoms you describe.

You could extend the 'bunched' earth wires with a single heavy black wire to the chassis bolt, having cleaned everything up first. Assemble with silicone grease to prevent further oxidisation.
Nick

[Nosh]

debaron said:

When i've got my lights on the water temp gauge reads high by 5 degs or so.

If I turn them off, water temp drops immediately by 5 degs.

Temp changes with lights on / off - I had this.

Have checked all earths (including 'nipping up' the nice 'shiny' ones in the transmission tunnel) and the problem has gone. HOWEVER - I say 'all earths', but I haven't done the radiator one yet....

Hope this helps
Nosh

Edited by Nosh on Tuesday 25th January 18:47

Edited by Nosh on Tuesday 25th January 18:48

Edited by Nosh on Tuesday 25th January 18:49

[debaron]

Thanks guys - will take a look and post back with results.
Had the rad out before - not too tricky a job. I find that tabasco sauce bottles ideal size for blocking up the hoses so the coolant stays in the block!

Hoping it's just a manky battery though.

cheers


Ryan