1973 911 what is this blinking red light!?

Ytouf · 05:22 AM

On my 73 I have a blinking red light on the oil pressure guage. Its the top light, it blinks while driving and at idle. Oil pressure is good, I was told in the engine rebuilding forum it was a braking issue. So its a brake light....what does that mean!?! Sorry to sound so stupid but I don't like digging on Porsches (expensive parts/complex design) until I get an idea of what I am looking for. Thanks guys.

EDIT: And also, if my Porsche originally had fuel injection on the 2.4 but now has Webers does that mean it was a 911E?

jhladousa · 04-28-2006, 05:26 AM

In my 1975 that light is on when the parking brake is engaged.

Ytouf · 04-28-2006, 05:51 AM

The bottom light is definetly generator correct? The top is brake correct?

jhladousa · 04-28-2006, 05:54 AM

According to my manual, yes. The bottom light on my car usually comes on when I start the car and will stay on until the engine hits a certain rev. It then goes out and stays out for the rest of the drive.

Ytouf · 04-28-2006, 06:00 AM

So my car thinks the parking brake is on when it is not. That is odd...

HarryD · 04-28-2006, 06:05 AM

The top light indicates that either the handbrake is activated OR the switch in your master cylinder has been activated due to a hydraulic problem.

When did this start? Suddenly? After you bled your brakes? After a big bump?

Are you brakes working ok? Do you have a reasonable stopping distance and firm pedal? If so, the switch may have gone bad and needs replacement.

oldE · 04-28-2006, 06:20 AM

"And also, if my Porsche originally had fuel injection on the 2.4 but now has Webers does that mean it was a 911E?"

Not necessarily, all 911s of that vintage, destined for the US market had fuel injection. Post the car's serial number, someone will quickly tell you what it is/was.
Les

donstevens · donstevens's Garage

The blinkinkin upper red light indicates that the parking brake is on. So yes, the car does think the parking brake is on. It is probably just the switch. Make sure that the handle is all the way down, no carpet has it hung up, etc.

If everything is OK there the switch is probably bad. There is undoudtedly a way to disable the switch but I'll leave the "how to" to someone with more knowledge than I.

Good luck,

Don

Sunroof · 04-28-2006, 07:01 AM

Its definitely your parking brake light and often it will have an accompanying "clicking" sound to alert you that its on. As the cars age, that switch under the brake handle wears and you have to make sure your branke handle is always in the full down position. Experiment and raise thehandle slowly to see at what height it comes on.

If; however, the light on the bottom of the gauge goes on......STOP EVERYTHING!! Thats your alternator/charging system and if a light rev does not get it off, you'll need to chase the cause down.

Welcome to Porschedome!!!!!!!!!

Bob
73.5T

Ytouf · 04-28-2006, 07:11 AM

Ok so its the switch on the handle. I will play with it and WD-40 it to see if its just corroded on the inside. The light has been one since I bought her a couple days ago. The car stops fine its just got that light flashing constantly. Right next to the hand brake is a "Throttle" lever. What does that do?

HarryD · 04-28-2006, 07:30 AM

Ytouf,

While the other respondents are fixated on the parking brake handle, I know that when my brake light started blinking on my 1973, it was a corroded switch on my master cylinder since the problem stopped when I unplugged the switch.

For the hand throttle, do you have the factory fuel injection still on your car? Is it the MFI or the CIS?

For my CIS car, you pull the handle all the way up when you start the car. It does 2 things, Opens the throttle plate to admit some air and, when you crank the engine, it squirts some extra fuel via a 7th injector to help the car start. Once started, lower the rpms to about 1,500-2,000 until it gets warm.

Joe Bob · Joe Bob's Garage

WD 40 sucks....use a REAL penetrant. WD stands for water dispersant.

Try PB Blaster....

Christien · Christien's Garage

Ytouf,

That light also flashes when your 4-way signal lights (hazards) are on. In my car, there's a wiring problem with the ignition and 4-ways, so my light is also constantly flashing, yet it has nothing to do with my parking brake, or regular brakes (just put in a new master cylinder last year). It started happening as soon as I messed with my ignition wiring.

HarryD · 04-28-2006, 08:00 AM

Christien,

My 4 way flashers do not activate the red brake warning light, only the directional flashers. Sounds like you have some serious wiring issues. A review of the wiring digram also shows that the brake warning lamp is wired only to the handbrake and the master cylinder.

Christien · Christien's Garage

Hmm, could be the wiring was messed up when I bought the car (it used to flash when the 4-ways were engaged), before I screwed it up even worse. Thanks for the tip. It's one of those things I want to get to, but it's pretty low on the priority list...

daepp · 04-28-2006, 09:11 AM

With respect to the top red light - I thought it had a dual (or perhaps triple) purpose:

1 a) Parking brake on
b) Brake master cylinder proportioning valve detects imbalance

2 Zero oil pressure

Is this not so?

billwagnon · 04-28-2006, 09:20 AM

there's a little reset button on the master cylinder that stops the light from blinking. I think the blinking starts if the fluid level is too low.

when I replaced my master cylinder I put everything back together, then had to take it apart to get to the button so the flashing would stop.

or you may have a bad master cylinder.

HarryD · 04-28-2006, 09:25 AM

Quote:

Originally posted by daepp
With respect to the top red light - I thought it had a dual (or perhaps triple) purpose:

1 a) Parking brake on
b) Brake master cylinder proportioning valve detects imbalance

2 Zero oil pressure

Is this not so?

On a '73 the red lamp is only for the parking brake and master cylinder. There is no oil pressure switch on the car.

HarryD · 04-28-2006, 09:26 AM

Quote:

Originally posted by billwagnon
there's a little reset button on the master cylinder that stops the light from blinking. I think the blinking starts if the fluid level is too low.

when I replaced my master cylinder I put everything back together, then had to take it apart to get to the button so the flashing would stop.

or you may have a bad master cylinder.

Perhaps I am ignorant but my master cylinder did not appear to have any sort of reset button. I think it may have come on later units.

donstevens · donstevens's Garage

Quote:

Originally posted by Ytouf
Right next to the hand brake is a "Throttle" lever. What does that do?

If your car has Webers, the throttle thingy does absolutely nothing. It was there for cold start when you car had fuel injection.

Now, just for fun and for our curiosity, we need to determine what fuel injection your car had. It could have been MFI or CIS. Your VIN number will tell us that. Please post the VIN ASAP. Also, please post a photo. We luv photos.

Thanks,

Don