1.6 Gti Alternator/ignition Lamp Troubles

[Guest Jamese30]

I have recently bought a 1990 1.6 GTI.

 

The battery has always sounded a bit low on charge when starting but hte car always seemed to fire up ok. The other weekend I drove about 200 miles, and noticed that when I came off the motorway and rolled up to some traffic lights, having gone into neutral and let the revs drop the Ignition & oil pressure, oil temp lights flashed on before the revs picked up again - Is this normal??????

 

After the return journey, with headlamps on etc. the battery was flat, and had a small leak form one cell so I replaced it with a new battery. I did an alternator check and the car returned 14.4V on idle. Two 30 mile journeys later and one evening while driving all the headlights and interior lights went dim and very quickly the car ran to a stop.

 

I got towed home and on the drive jump started it and did an alternator check - 11.6V so time for anew alternator.

 

I have now fitted the new unit and I am reading 13.6V on idle with no accessories running and 12.6V with all lamps/etc on - so all seemed ok.

 

However, on a trip last night, I noticed that again after driving 20 miles with the lights on as I rolled up to traffic lights i neutral, foot off the throttle again the ignition lights momentarily flashed on. By reving the engine and thne letting the revs drop the ignition lights would flash on again before the car reutrned to idle speed. - Has anyone else experienced this?????

 

An alternator check last night revealed 13.6V on idle and 12.6V idle with all accessories on.- are these noraml readings???

 

Any help would be much appreciated.

 

Thanks,

 

James

[jackherer 543]

Those voltages are a bit low, time to check the gearbox earth strap and the battery terminals etc. Does the battery light come on when you turn the ignition on then go off when you start the engine?

[Guest Jamese30]

Those voltages are a bit low, time to check the gearbox earth strap and the battery terminals etc. Does the battery light come on when you turn the ignition on then go off when you start the engine?

 

Hi jackherer,

The battery light doesn't come on with the ignition on. It has only come on once and that was when the battery was failing, and that wasjust a flicker.

 

The battery terminals are ok, I have cleaned them up and voltage across them is good.

 

WWould the gearbox earth strap cause this? Where does this connect to?

[jackherer 543]

The battery light is controlled by a small wire that connects to the alternator via a spade connector. If this isn't connected it can stop the alternator from charging (although usually they start charging without it when they hit about 3000 rpm).

 

If this wire is connected to the alternator check the spade connector isn't corroded then follow the wire to the brown multiplug and check the condition of that. You can test it by grounding the spade connector which should make the battery light come on.

[Guest Jamese30]

The battery light is controlled by a small wire that connects to the alternator via a spade connector. If this isn't connected it can stop the alternator from charging (although usually they start charging without it when they hit about 3000 rpm).

 

If this wire is connected to the alternator check the spade connector isn't corroded then follow the wire to the brown multiplug and check the condition of that. You can test it by grounding the spade connector which should make the battery light come on.

 

I refitted that spade connector to the new alternator so should be ok but will check it.

 

Sorry for sounding stupid but just to be clear for me, is the battery light on the dashboard the actual symbol of a battery as opposed to the "STOP" light??

 

Should the battery symbol light come on when I turn the ignition on?

Edited March 17, 2008 by Jamese30

[welshpug 1,657]

yes, and should go off when you start the engine, unless there's a charging fault.

[Guest Jamese30]

Sorry - reference my post earlier. Checked the car last night and the battery symbol does illuminate when the ignition is switched on and then goes off immediately afterwards so it is working fine.

 

I did a voltage check with the engine cold last night:-

 

14.4V without anything on

13.6V with heated rear window, main beam, hazards, fog and wipers on.

 

After turning the engine off I then removed the earthing spade connector and did a voltage check and got a reading of 12.0V across the battery because the alternator was then not working.

 

I also checked the earth strap to the gearbox and all seemed secure and ok. I checkedthe earth straps as well and they were ok.

 

So, I guess my only two questions are: -

 

1) Does anyone ever see their ignition lights flicker on momentarily as they roll up to traffic lights/stand still in neutral after coming off the throttle? When I do this on my car the revs drop momentarily below idle (this is when the lightas come on), and once they pick up the lights go off. It sounds like it might be a normal warning as at those revs the alternator will not be powered enough to charge the battery.

 

2) Does anyone see the "charging" voltage across their battery change between hot (14.4V) or cold (13.6V)? Are the alternators clever enough to reduce charge into the battery when it is in a fully charged state.

 

Thanks again for your help so far,

 

James