Electrickery nightmare

Hi everyone, i am a relative new member to the golf scene but have been mssing with cars since i could chuck a spanner however this mk1 has got me right confused. My problems are three things which i belive may be connected. Firstly the headlights and interior dash lights are flashing/pulsating when driving. Revs seem to make no difference and have tested the battery and is okay and getting a good 13+ volts when running so assume a good supply from the alternator. The only thing i have noticed is it seems okay when idling so i wonder if there is a cable vibrating or not earthing properly when its moving? Also the oil pressure light has statred glowing on and off dimly sometimes, engine has oil and is not noisy. wondering if is related to problem above? Noticed last night the battery light very dimly almost cant see it glowing at night.
My thoughts are earth not good, regulator, alternator, oil pressure switch, or combination of the above. any help???

One ofthe first things that Id check if you have a problem with the dash lights and it's functions, would be the earth strap on the rocker cover.
It should be located onthe rear right stud as you look at the engine. The wire is brown.

Without that connected you will get problems with your MFA display, lights and warning bulbs.

Try that first and report back.

Dan

Okay will do, thought it might be a lead from the engine to the chassis somewhere as it seems to be as the engine rocks that it plays up, will also check the oil switch as per some tips i found on here earlier. cheers for the help

Alternator should give a healthy 14+ volts with lights on . Check with a digi meter .

Yep alternator all good, 14.38 volts or there abouts. Just checked rocker earth, cleaned up and noticed it may have been a bit loose, will see how we go. Any ideas on why the headlights are dimming along with the dash lights??

for your oil pressure light coming on , sometimes this could be a faulty sensor , or it could be loose , or bad earthing , new sensor you can pick up from gsf for 2.58, got one yesterday , hope any of this helps

Anyone got any more ideas on my headlights and dash lights dimming. Noticed tonight the reverse lights are pulsing too. The dash lights seem to be behaving now after i cleaned the earths up. I am suspecting the alternator regulator being duff or maybe even the battery. Any ideas folks

Sorry to contridict people, but an alternator is exactly that, it supplies an alternating voltage, you can't test an alternator with a Digital meter because it gives you an average figure. Its true to say if its giveing you <12v or >15v something wrong, but then you wouldn't be testing it if nothing was wrong.

A flat battery can also give you a low reading to start with, as can a bad alternator, or a bad earth, or bad positive cables, etc etc…

There are ways to properly check it, using an analog meter would give you an indication, but a load bench is the best way, and only true way as an alternator regulator(and it usually is the regulator) can break down under certain loading and temperatures.

From what you've said if you've cleaned up the earths and it seems to be fine, that is what the problem was and you should have no more trouble.

Other things to look at are unusual loads on the alternator such as car amplifiers and extra fog lights.

As for the oil light, as previously mentioned the sensor, or could even be the wiring to the dash and/or earths again.

Hi thanks but i think the dash warning lights glowing and the headlights dimming are seperate issues. Cealing up the rocker cover earth seems to have sorted the dash lights but the headlights are still doing a good impression of a strobe light when running.  

Isn't there a rectifier built into the alternator nowadays.
I had trouble with the dash lights going out along with the rear lights, the fault turned out to be with the plug on the back of the relay/fuse plate. I cleaned them all and pinched the sockets slightly with a long nosed pliers, I've had no trouble since, it might be worth trying the same thing with yours.

cedar said

Isn't there a rectifier built into the alternator nowadays.
I had trouble with the dash lights going out along with the rear lights, the fault turned out to be with the plug on the back of the relay/fuse plate. I cleaned them all and pinched the sockets slightly with a long nosed pliers, I've had no trouble since, it might be worth trying the same thing with yours.

Yes, in a roundabout way thats what I was saying is faulty =)

Reason for me thinking this is because the alternator supplies a varying voltage between 0v and 14v (probably higher in fact depending on revs) alternatly i.e like AC mains (hence the name) and the voltage regulator is what smooths this out and turns it into a DC voltage that the cars needs to run.

If the lights are flickering/dimming or similar it means theres a disruption to this part of the circuit, either the load on the alternator is too great and/or the regulator is not doing its job. The regulator on a car is a very simple one which is why you sometimes get alternator whine on your car stereo.

As with any electrical problem it can also be caused by faulty wiring, including poor earths.

Thanks for all the help, i suspect the alternator then. Will whip it off and take it to the local alternator place for testing. Any ideas what it cost to replace regulator or is it cheaper to get a second hand one of ebay or somit. cheers

I had one done for about ?15, might depend on your alternator.

clean up all the battery, starter and alternator wiring as well, i had similar issue with battery light on dim and it was becuase i forgot to do up the chunky alt wire nut after the engien swap