Flashing Temp Light
 

On my drive to work, the temp light began slowly flashing.

New tank, new cap, temp normal, coolant tank half full......

Any ideas?

From a Search for the explanation....

From Loren@ rennlist -- 12 years ago!

Here is the long explaination from the service manual on the flashing coolant light.

"Four functions of the coolant warning light:
1. Engine coolant level too low -- light flashes slowly (0.5 Hz)
2. Engine compartment temperature too high -- light flashes slowly (0.5 Hz) (engine compartment blower might be faulty)
3. Engine coolant temperature too high -- light is lit; pointer on the right
4. Temperature sensor at water outlet faulty -- light flashes rapidly (1 Hz) ; pointer on the right

Note: The temperature warning in point three is indicated if the conditions "engine coolant temperature too high" and "engine coolant level too low" are present simultaneously."


If you have replaced things -- I would check that the sensor connection is secure, or maybe replace the sensor.

Mike

Does it dead cold ....

Than it has to be something related to the coolant level sensor.

It's either bad or poorly connected.

Mike

A half filled coolant tank might be too low. There are indicators on the level sight and depending on what you consider half full might be just low enough to consider 'low'

I filled to coolant tank almost to the top at lunch today. Started the car from cold, light still blinking.

Left work at the end of the day, checked the level (still full), light still blinking.

At the same point on the highway where it started blinking this morning, but going in the opposite direction, it stopped blinking.

So I'm figuring some kind of coolant-level-sensor-underground-doggie-fence in the vicinity of Haddam CT as the likely culprit. Who's with me?

Watch closely in the coming days to ensure that you don't encounter intermix in the oil or coolant. This is a classic scenario that could be a precursor to something that you can catch early on.

I will.

At first I discounted it because I was having a heck of a time with my new coolant tank's bleeder valve AND the cap. I had condensation about the reservoir and it was a combination of a bad o-ring and the cap. It's been dry the past week but I thought perhaps through all the fiddling enough had evaporated to make the level borderline. Kind of surprised that topping it off didn't eliminate the light.

Jake -

I've been pondering this.

With a cold engine, I filled the coolant tank to the filler neck and started the engine. The light slowly blinked immediately, indicating low coolant which was clearly not the case.

Do you agree that it must be the sensor?

TIA

It would either be the coolant level sensor gone bad, or the engine compartment sensor gone bad, since either can trigger the slow blinking coolant light.

And a week later, it started flashing again. Coolant tank is full, and even does it from dead cold so the overheated engine compartment doesn't make sense.

Unplugged the coolant level sensor and tried (as best I could in the dark) jumping the connector with a paper clip. Didn't help.

Any thoughts?

And: Where is the engine compartment temp sensor?

Beuhler? Beuhler?

Hahah.

Well the problem is one of two dead sensors then (or both). I'm not sure what a good 'full' reading looks like to the ecu from the coolant level sensor, so shorting the two wires might still mean 'coolant level low' to the computer.

Since it probably DOES work like you thought (two wires shorted when coolant level is good), check the engine temp sensor. Its on the passenger side intake manifold between the throttle body and the plenums that attach to the head, you cant miss it, its the only sensor with wires coming out of it atop the passenger intake. Maybe there are some docs online that explain how each sensor works so you can test them (I dont have the bentley book with me all summer)

If you had a durametric you could take a look at the engine compartment temperature. That would show that value that the engine compartment sensor is sending. When I had that issue, it was the engine compartment sensor fell out of it's grommet and was laying on the manifold. That would not explain a blinking light when the engine it cold but a durametric will show the value it is sending (e.g. is that sensor bad. I also wonder if the engine compartment sensor was bad if the engine compartment fan would be running????

You would think that if it thought the compartment was overheated, the fans would be going full bore.

In Porsche fashion, they decided to go the other way - the coolant level sensor is a normally open circuit. Unplugging the connector made the light stop flashing. Who da thunk it?

Did u check the coolant temp reservoir?

I think I know what you mean, and - yes - the level has been fine all along.

Another pleasant hour of my Sunday dealing with Porsche "engineering" (if it can be called that).

Replaced the coolant level sensor with new, plugged it in, and drumroll ----- the light still flashes. So, if it's unplugged it doesn't flash. Which it currently is. I'm not going to get into the rank stupidity that has me remove 2 pieces of carpet and then loosen the entire tank to get the sensor out because they thought it would be a grand idea to position the sensor directly above one of the body seams so you can't drop it out without a written consent decree.

I guess it has to be the float? I can see that it is at the top of it's travel when it reaches a push-on retaining clip. Maybe I should somehow push the clip farther down the float's spindle?

Did you check the engine compartment temp sensor for proper functionality?

Nope. It has to be related to the coolant level sensor since disconnecting it causes the light to stop flashing. Otherwise implies that they are wired in series, which doesn't make sense - even for Porsche hahah.

Oh, I missed the part where disconnecting it made a difference in the light, my bad.


Yeah, probably something in the tank then, since you replaced the complete switch. Maybe replace the tank if it is yellowed and old anyways? Or just leave the sensor unplugged and YOLO a little bit...:eek:

I installed a new tank in May when I did the IMS..... no way I'm taking that thing out again!!

Any luck with the light
 

were you ever able to figure out what was wrong. I have 1999 doing the same thing now

John

FYI, this thread is over 3 years old. You may not get a response from the OP.

I didn't... as a matter of fact, I had the carpet out this spring and connected the sensor again and it started flashing so it's disconnected again.

Thanks for the insight
 

I know this is an old thread, but it was really helpful. I have a similar problem that I have been trying to diagnose. I replaced the coolant cap, engine compartment temperature sensor and coolant level sensor, but still the light keeps blinking. I have tried to check the wiring with the assumption that the circuit is normally closed when the coolant is topped off. This thread gave me the tip that full = normally open. I disconnected the connector to the coolant sensor and the light went off. Real progress! Thanks

Now I need to figure out why the circuit is closed with the connector attached and full on coolant, but that should easy now that I understand the system logic.

Yeah, this is old! Sold the car years ago, never did figure it out. Just left it disconnected. Still see that car driving around tho! New owner is definitely in over his head.... Explained oil changes to him and he said he would just let the dealer do it. This from a guy with 3 teens/tweens, a tiny house and college on the way.

Yeah, this is old! Sold the car years ago, never did figure it out. Just left it disconnected. Still see that car driving around tho! New owner is definitely in over his head.... Explained oil changes to him and he said he would just let the dealer do it. This from a guy with 3 teens/tweens, a tiny house and college on the way.,and couldn't drive a stick

Just a follow up. My problem is solved. It was a stuck float. The float was stuck at a low fluid level even though the coolant was topped off. I figured it out by pushing down on the float with a screw driver to check the function of the switch while a VOM was attached to it. It was then I discovered the switch worked right when pushed on the float a couple of times.

The crazy thing is I have driven it over 2000 miles with that light blinking! So it was stuck all that time.

The simplest things sometimes.