Seat belt light

[89cab]

I have a 89 911 and my seat belt light turns on for a few seconds and turns off while I am driving,and I noticed when running my a/c the fan ramps up ans down in high speed.I am thinking it might be my Voltage Reg inside alternator.Any sugestions

[86 911 Targa]

89cab

We experienced the same symptoms, (without the seat belt light) a few years ago, and it was indeed the voltage regulator.

Replacing the regulator is not a major effort.

This procedure is well covered in the Bentley manual. (pages 270-11 thru 270-16)

However, I had to notch out the plastic air funnel in order to accomodate the new regulator.

This issue should be resolved ASAP as to preserve your battery.

Any battery shop can test your system and fault isolate the issue.

Your voltage regulator should deliver about 13.5 volts to the battery.

Also, note how many shims are between the pulley halves, and under the cup washer.

All six shims must be on the alternator shaft.

The Porsche fan belt P/N is 999.192.176.50 (9.5X710mm)

You may also want to replace the A/C belt as it must be removed for access to the alternator.

Good luck,

Gerry

[86 911 Targa]

And here is the alternator shim layout.

Our's used two shims between pulley halves and four under the cup washer.

Good luck,

Gerry

[89cab]

I thought that was the problem,I just replaced the belts recently and I pretty sure the shims are correct but wouldn't my headlights and other instruments lights trip out to.