Battery light will not illuminate on start up

Hello everyone,

Have not posted on here for a while due to the Golfs hibernation…Well,after getting the car up and running again i have noticed that on turning the ignition on i only get the oil warning light that flashes…..no battery light..The car will start ok but at the moment revs a bit high.Wasnt sure if any of you have come up against this before and if im missing something.

Thanks
Sean

I would ask if you have checked the voltage at the battery terminal?

The Battery light is used as the exciter for the alternator.
The Exciter starts the Field coils so the alternator can turn on.  It has a direct feed via the Battery to the Dash and back out the cluster to the Alternator (blue) wire on Bosch alts, and black on Motorola usually.

Without the exciter the alternator usually doesn't turn on at all and you are running out of the charge on the battery.

I would check the Charge of the Battery, and clean the connections, both at the battery and the frame as well as the Positive.

This little lamp if it goes out (burns out or the diode goes, can cause you grief.

Basically the Battery runs through the lamp and a Diode back to the Alternator.

It builds the fields as a tickler or exciter, once the Alternator builds the field it starts charging the battery, and the voltage on the lamps output exceeds the input, and turns off.

Bulbs do burn out, Diodes go bad, as well as the connections to the "Blue or Black" wire to the alternator.

You can test the Bulb at the cluster to eliminate it, or discover that the Bulb is bad with a 9V dc battery.

Lower the Cluster and Place the Negative side of the battery to the Brown wire and Positive on the blue wire into the cluster, and the lamp should glow.

I have seen Voltage Regulators go bad and cause a similar issue which you can also test for by disconnecting the Plug on the Motorola, and or the Blue exciter on Bosch.  If the Lamp then works with Key on, your issue is with the Voltage regulator in the Alternator

If the lamp is still out, then you have a issue with the wires feeding the lamp, and or going to the Alternator or the lamp itself.

I have just put a new battery on the car,but to be honest whilst it was laying up i did remove and clean the alternator.So i will go back and check all my connections.
Thank you for the excellent advice.

Sean

I've had the same before, although wasn't on a MK1. It was the small cable from the alternator - it had baked and gone hard and brittle so there was a break in it.

It's worth checking that cable for continuity if you've got a multimeter.

Massive shout out and thanks Briano1234 your write up of what to do was easy to follow and helped me out in a big way 👌🏻 I was about to splash out for a new alternator till I read it! You saved me some 💷💷 so again thank you

karl9779 said

Massive shout out and thanks Briano1234 your write up of what to do was easy to follow and helped me out in a big way 👌🏻 I was about to splash out for a new alternator till I read it! You saved me some 💷💷 so again thank you

So what was bad or what fixed it?

I found a break in the exciter wire as it entered the engine bay, before reading the post I was just going to try a new alternator on there

Thank you for the conclusion and repair, it helps others….

im resurrecting a few of your old feeds on here Briano1234. It seems like i have several issues with the car as you know. Now im tracing down this alternator / charging/ wire melting issue and also have this battery no light issue…………gonna work through your little write up on here also as part of the diagnostics.  

responded on your original text