Help - Electrical problem?

[laundromatt]

Hi everyone,

I have a small problem that I need some help with.

When I'm driving, all of a sudden, the seat belt light will come on, and my radio will turn off. The car will be driving along fine. Then, after a short while, the seat belt light will go off and the radio will turn back on. At first, I thought it happened only when I drove on bumpy roads, but now, it just happens for no apparent reason. Anyone have any ideas or advice?

Thanks!

[dicklague]

Do you need either of those in a 911?? ;-) !!

[laundromatt]

Haha, good point. Normally no, but there are times where I want to listen to the game on AM radio.

[86 911 Targa]

Originally Posted by laundromatt

Hi everyone,

I have a small problem that I need some help with.

When I'm driving, all of a sudden, the seat belt light will come on, and my radio will turn off. The car will be driving along fine. Then, after a short while, the seat belt light will go off and the radio will turn back on. At first, I thought it happened only when I drove on bumpy roads, but now, it just happens for no apparent reason. Anyone have any ideas or advice?

Thanks!

Do you have a Bentley and a multimeter?

[Walter_Middie]

There have been a couple of posts lately on seat belt lights that come on. I pay attention to them because mine does the same thing. During acceleration, sometimes my seatbelt light comes on. Most say this is due to an over active voltage regulator. I think historically this has been the answer.

I put a volt meter on mine, and didn't notice any change in the voltage when the light came on. That doesn't mean it isn't somehow the voltage regulator, but I am still in the process of trying to find a better answer.

[86 911 Targa]

Originally Posted by Walter_Middie

There have been a couple of posts lately on seat belt lights that come on. I pay attention to them because mine does the same thing. During acceleration, sometimes my seatbelt light comes on. Most say this is due to an over active voltage regulator. I think historically this has been the answer.

I put a volt meter on mine, and didn't notice any change in the voltage when the light came on. That doesn't mean it isn't somehow the voltage regulator, but I am still in the process of trying to find a better answer.

I do not understand the relationship between the combination indicator lamp, and the oil pressure switch.

However, we had the same symptom(s) when the oil pressure switch started to fail.

Replaced the switch, and all is well.

Check for oil around the switch.

Good luck,

Gerry

[laundromatt]

Originally Posted by 86 911 Targa

Do you have a Bentley and a multimeter?

I have a multimeter, but no Bentley. Can you explain what I should do with the multimeter?

[scotyp]

Gerry,

I have just looked at this page in the Bentley. My 82' SC is having this issue now. My oil pressure light comes on at the same time as my parking brake light. I have no idea why Porsche decided to gang these two together.
I'm thinking my oil pressure switch is bad and will need to be replaced. Can you do this without a partial engine drop or can you go in from the engine compartment. Looks like a b****h to get to!

Scot

[laundromatt]

Just to clarify - my oil pressure light does not come on at all. So maybe I have a different problem? Anyone have any advice?

[laundromatt]

anyone?

[911pcars]

The electrical ground is a common electrical point for many loads in the circuit. Locate and ID the ground for the radio and seat belt circuit; you might find the culprit there.

MHO,
Sherwood

[dshepp806]

Agreed,..I'd make sure it's not a pesky ground point FIRST!


Doyle

[Icemaster]

Do your headlights change brightness slightly when this happens?

You're more than likely looking at a voltage regulator replacement. There's a very simple test that you can do that involves putting you VM on the battery to see what it reads while the car is running, should be between 13.3 and 13.7 volts IIRC.

I'll be damned if I can find it, but there's a bunch of threads on this forum about troubleshooting and replacing the VR. Start small with the easy tests.

[86 911 Targa]

Originally Posted by scotyp

Gerry,

I have just looked at this page in the Bentley. My 82' SC is having this issue now. My oil pressure light comes on at the same time as my parking brake light. I have no idea why Porsche decided to gang these two together.
I'm thinking my oil pressure switch is bad and will need to be replaced. Can you do this without a partial engine drop or can you go in from the engine compartment. Looks like a b****h to get to!

Scot

It is.

You may be in for an engine drop.

On the 3.2 motors no engine drop is required.

You may pm me as required.

Gerry

[laundromatt]

Originally Posted by 911pcars

The electrical ground is a common electrical point for many loads in the circuit. Locate and ID the ground for the radio and seat belt circuit; you might find the culprit there.

MHO,
Sherwood

Thanks for the tip. Can you give me some pointers on how to do this? I don't have a Bentley, so I don't know where/what the circuits are, and where they come into contact with ground. Thanks!

[911pcar]

Originally Posted by laundromatt

Thanks for the tip. Can you give me some pointers on how to do this? I don't have a Bentley, so I don't know where/what the circuits are, and where they come into contact with ground. Thanks!

Tools and equipment needed:
- standard hand tools
- something cushioned to lie on
- drop light
- Advil (for your back)

I don't know the Bentley manual to tell you if they ID the locations of the various ground junction points to the chassis. There's one under the dash. I'd look there first since it's closest to the issue area (German ground wires tend to be brown) and it's probably faster than finding some photos/illustrations of the ground connections. It might be loose, dirty and/or corroded. Remove all wire connectors, then clean them to base metal with fine emery or equivalent. Other electrical circuits are normal, yes?

Sherwood