Oil temp warning lamp mystery

[Kugelfisher]

I have a problem with my 1972 911T Sportomatic. When I start the engine, the oil temperature warning lamp AND both turn signal indicator lamps starts blinking. This continues as long as the engine is running....

Thankful for all good ideas!

[ossiblue]

I'm not familiar with a sportomatic, does it have an oil warning light? Is it for the oil in the sportomatic trans? My 73.5 (manual trans) doesn't have an oil light--only temp gauge. The lights are for the brakes and alternator. Could the lights be from the brake warning light and turn indicator?

Another thought (assuming you have an oil temp light.) Do you hear the "clicking" of the turn signal relay while the lights blink? Listen closely--it's located just behind the fuel gauge in the luggage compartment. If you don't hear it, the blinking must be caused by another relay--emergency brake, seat belt, or oil temp. If that's the case, if you are sure the cause of the blink is not from a legitimate warning, then it sounds like a current leak somewhere that's causing the turn light indicators to flash, most likely a poor ground, but that doesn't explain why the oil temp light flashes. In short (pardon the pun) it sounds like you have two problems--something's tripping the oil temp light, and a current leak affecting the turn lights.
Do a little investigating, and keep us up to date.

[Kugelfisher]

ossiblue, you are right. It is the the brake warning light and turn indicator that is flashing. The sportomatic does have a oil temp warning lamp as well, but this is located in the upper part of the oil temp scale. Sorry, my mistake....
New info: If I choose left (or right) turn signal, the indicator lamp acts normally. (only left arrow flashing, with normal frequency). But the brake warning lamp follows, with the same frequency....

[ossiblue]

Lars,

Still sounds like two problems since the flashing occurs continually with the engine on. Most likely, the brake warning system is being activated and you have a current leak (poor grounds?). Track down all possible causes for the brake warning light, starting with the master cylinder (there is a pressure switch there). Be sure your brake system is good and the pressure switch is good. Take care of this first!

If that checks out, inspect the emergency brake switch--it's located on the passenger side of the base of the emergency brake handle (you can see the slot-head screw that is used for adjustment from the outside.) With the e-brake handle all the way down, try adjusting the switch downward in its slot and see if the blinking stops. If it doesn't, you may have to unplug the wire to the switch which should put the light out. Then, you can replace the switch (which requires removal of the e-brake handle.) If the blinking stops with the readjustment, pull the handle up one click, and move the switch up slowly until the blinking starts.

This should get you started. Solve the mystery of the flashing light first, then worry about why the turn signal indicators flash. That's minor by comparison. Let us know what you find.

[Kugelfisher]

ossiblue, thank you for your follow up!

I think I will start with a new brake master cylinder. My brake pedal feels soft and I have to push very, very hard to lock my wheels... I'll keep you posted.

Lars

[Joe Bob]

Might want to get a manual for the car. Porsche still sells reproductions. I was able to get one for a 58 356 A from the dealer......