Dimly glowing charge light.... alternator kippered?

larrylamb11 · Post by **larrylamb11** » Fri Feb 16, 2007 3:51 pm

I was smoking about in my V8-mobile last night and noticed the charge light very dimly glowing on the dashboard with the headlights on, glowing slightly brighter with the lights on high beam and brighter still the more electrical load you apply - it doesnt glow at all with the engine running and no heavy electrical items on. I have just fitted a new battery as the old one died, the cells under the battery posts went dry (not completely, just had less water in than the others) and now i suspect that i may actually have had a charging problem all along too. It does have a volt-meter and that seems to read pretty much OK, although it creeps lower the more electrical load you apply and hovers perilously close to the bottom of the normal band when loaded - reading the volts off the battery with a meter and no load looks ok around 13.6V..... So i guess the alternator is struggling some way or another, question is does anyone recognise these symptoms as anything particular? field windings or diode pack? or think there may be something else at the root of it?

Post by **Coops** » Fri Feb 16, 2007 4:44 pm

have you checked for an earthing problem???

GreenV8S · Post by **GreenV8S** » Fri Feb 16, 2007 8:19 pm

The way these are usually wired up, the warning light is connected between the switched ignition circuit and the alternator. It comes on if the alternator output is low, but also if the switched ignition circuit is low. The ignition circuit can dip just because of electrical loads on it - heater, sometimes lights etc. This will be more noticeable if you have a poor connection anywhere along the path between between the battery and the switched ignition circuit.

kiwicar · Post by **kiwicar** » Fri Feb 16, 2007 9:30 pm

I know it's an obvious one but is the fanbelt the right tension/ old and knackered/got oil/salt water on it? would be worth a check before you change the alternator.
Mike

mikeinatruck · Post by **mikeinatruck** » Fri Feb 16, 2007 9:35 pm

Does the light illuminate correctly when the ignition is just on? The ignitiion light goes to earth thru the alternator and when its charging it puts a supply back up the wire so it cant go to earth and puts the light out.
Sounds to me like the alternator could be on the way out but I would check the wiring for continuity first.

rob b · Post by **rob b** » Sat Feb 17, 2007 7:34 am

on the way home from buying my V8 beast i noticed that the light was glowing but was very very dim, you could only see it when it was dark. the next day i checked my alternator output and it was 30 volts

it had just had a new battery fitted by the previous owner as well, it probably got fried by the alternator problem, just a thought sounds the same as my problem that.

rob

ChrisJC · Post by **ChrisJC** » Mon Feb 19, 2007 1:24 pm

Whenever I've had the charge light glowing dimly when the headlights are on, it's been the alternator.

Chris.

Wizardof · Post by **Wizardof** » Thu Feb 22, 2007 3:46 pm

I had a very similar problem with my V8 as well. that turned out to be a bad earth. It was a right pain to find, but once fixed the problem stopped. I assumed that as the wiring loom had been pulled about and modified a lot with the fitting of the new engine there would be problems like this...

mgbv8 · Post by **mgbv8** » Thu Feb 22, 2007 8:30 pm

Run a temporary earth wire from the engine to a good chassis earth point to see if it makes a difference. You can buy ready made leads at halfords. I put one form the alternator bracket to a good earth on the inner wing and it solved my problem like this.

larrylamb11 · Post by **larrylamb11** » Mon Mar 19, 2007 8:00 am

Changing the alternator fixed this.