Electrical Issues

[LawrieS]

Recently my S has started showing some signs of an electrical fault, I have no idea whatsoever regarding auto electronics so any help would be greatly appreciated.

My fan hasn't worked since I put everything together last winter, I think I can cope with diagnosing that one however, since I've had it the volt metre always sat in the middle (perfectly horizontal) once alternator had kicked in but now it sits slightly lower and falls when for instance the indicators are used or the headlights turned on.

Not really sure where to start? It doesn't drop or raise for turning the heater fan on or off, does that indicate a problem purely with the lighting circuit? Any other tests I could do?

I have an ammetre but no idea what to do with it

Thanks in advance.

Lawrie

[phillpot]

that dash mounted voltmeter is more trouble than it's worth (imho), ignore it.


Is your Ammeter a Multimeter, can it read volts DC?


If yes that's good if no go buy one.


Clip it, hold it, wedge it, somehow connect it across the battery terminals and set on the 20v dc range.


Engine off, read voltage.. around 12 volts?

Start engine and rev a little to get alternator charging (charge light out)... around 13-14 volts?

Switch some heavy loads on, headlights, heater fan, wipers etc.... still up at 13 volts+ ?

If yes, all is well, stick some black tape over the gauge and set about fixing the fan

[AMDBSTony]

LawrieS said:

Recently my S has started showing some signs of an electrical fault, I have no idea whatsoever regarding auto electronics so any help would be greatly appreciated.

My fan hasn't worked since I put everything together last winter, I think I can cope with diagnosing that one however, since I've had it the volt metre always sat in the middle (perfectly horizontal) once alternator had kicked in but now it sits slightly lower and falls when for instance the indicators are used or the headlights turned on.

Not really sure where to start? It doesn't drop or raise for turning the heater fan on or off, does that indicate a problem purely with the lighting circuit? Any other tests I could do?

I have an ammetre but no idea what to do with it

Thanks in advance.

Lawrie

Mine did something similar to this but in my case the voltmeter dropped when anything was switched on.

Basically the issue was due to the alarm being fitted and everything running through that circuit. There was 50A running through 2 cables and also heat was being generated through connections that were not designed to take such high current. Was lucky car didnt set on fire!

Cure was to basically rewire via relays to accomodate the more modern light and other electricals. Point of note was that for my car the EFi system was also being compromised due to fluctuating voltages.

All sorted now but cost quite a bit as had the injectors ultrasonically cleaned as well. Went whole hog and had new air mass meter fit with a new chip and then car was remapped on rolling road by Mark Adams.

Glad I went to such efforts in the end