Mark Brook

Dear All,

My fan belt/alternator light is coming on frequently. Belts are good condition and within tolerance, and there is no noticeable drain from the battery while the warning light is illuminated. It's pulling the following;-

Headlights on 13.70/80
Headlights off 13.93/95

I think these are all ok and within the limits. The battery is 6 months old, and the alternator has been rebuilt once, about five years ago.

Where do I look next to hunt the cause please???

Cheers,

Mark, 90C2.

Rocket Rob

For the fan belt light - Look at your fan belt tension sensor. Its a wheel to the left side of the belts. With the engine off, try to move it, is it touching the belt? Can you move the wheel? I've seen the bearing for these wear out and it turns the light on. I ended up replacing mine with a new unit. Some folks here have found the source of the bearing and repaired it.

For the alternator light - Do you have a digital volt meter? I would check your battery voltage with the engine off and with the engine on. The voltage off should be 12.5v and with the engine running, you should be between 13.5-14.0v.

bassie81

The sensor was an issue om my 1990 964 as well... Seems to break dowm after 20+ years

911Jetta

+1

my wheel flew off the senor!

Flea18

That'll do it. BTW is your belt installed inside out or does it have ribs on both sides?

Goughary

I just bought an M3 x20mm button head bolt, two washers and a nylock nut to reinforce the bearing shaft on mine since this has happened to three of my belt sensors . Hope to have resolved it now