Low Coolant Light

[logray]

Now I am really miffed. I removed and replaced the air pump so I could unplug the coolant level sensor, which I did. I too will have to buy some new nuts with rubber washer. Thank God there is still that upper nut which will hold it for now.

Took her out for a spin with Durametric hooked up. At 105c the light started flashing. The analog dash gauge read on the zero of 180, right edge. Coolant level fine. Sensor not hooked up.

Brought home to garage to chk purge fan. The purge engine compartment fan came on at 78.8c. I've been told the setting is 80c. Kept going to see when light would flash and it started at 97.5c coolant temp and 97.5 oil temp. I guess since I was at idle they came up together. For some reason I cannot get the A/C hack to work. I timed the on time of the flashing lamp and it was 1 sec. Any ideas would be appreciated. I am at a loss.

You can buy those rubber nuts at an auto parts store, they are called well nuts. I drove around for a long time with just the upper nut on as well. :)

So the DME reports 97C which is certainly not overheating. Did you also connect Durametric to the instrument cluster module to see what temperature it reports?

If the coolant level sensor was disconnected and the light is still flashing at 105C then my guess would be that the instrument cluster thinks the car is overheating or the or DME thinks the purge fan is not running.

I'm starting to run out of ideas too.

[ALLSPEED]

The Durametric 6 will not read the instrument cluster that I could find and Loren confirmed it. I hate to take it to our dealer. My 89 yr old Mother just fell and hit her head. This is common. I will be watching though. Anybody with any idea accepted. Loren, you're usually good on the hard ones. Where are you?

[Loren]

The Durametric 6 will not read the instrument cluster that I could find and Loren confirmed it. I hate to take it to our dealer. My 89 yr old Mother just fell and hit her head. This is common. I will be watching though. Anybody with any idea accepted. Loren, you're usually good on the hard ones. Where are you?

I have told you several times to replace the coolant tank sensor - I don't know what else to say...

[ALLSPEED]

Loren-I unplugged the level sensor and I still get the flashing lamp around 105c. I have trouble understanding the light flashing with the sensor disconnected. Could you please explain that to this knucklehead?

[Loren]

Covers all Carrera (996), GT3, TT / GT2 and Boxster (986) cars

Here is the long explanation 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."

[ALLSPEED]

Could it be condition 4 if I am getting a reasonable reading on the Durametric and the temp gauge on the dash? The Durametric is reading is at ECTS as I remember. I don't have it with me right now. The light flashes on for 1sec intervals. The dash gauge reads as it always has. Do they mean to the right of center or to max?

[logray]

Loren certainly has the goods sometimes... well done! :clapping:

.5 hertz is every 2 seconds.

1 hertz is every second.

If it is flashing every second... I am going to assume here that the #4 condition is part 99660640501 (<=2001) or 99660641000 (2002>), about a $25 part located on the oil pump housing, accessible from underneath passenger side rear of the engine sort in the middle behind the catalytic converter. #27 in the diagram below.

The sensor plugged into the oil/coolant housing sorta situated in the middle of the upper right portion of the console that bolts to the front of the engine.

And another pic of it located on the psngr side front of engine. The sensor looking thing on the left of the pic.

Edited September 21, 2011 by logray

[ALLSPEED]

I was wondering about the timing of the light. I measured the time it was lit which was approx. 1 sec. timed with my I-phone. It doesn't flash like any of these. It seemed like it was off for about 1 sec. also. Maybe I should time the off portion? I have to take a break from the car for a day or two of testing stuff to take care of my 89 yr. old Mom. I will be back. Thanks, Robert. P.S.- I would like to know if they mean the pointer to far right which it isn't but it seems that sensor may be the only thing left. thanks to logray for trying so hard to help me.

Edited September 21, 2011 by ALLSPEED

[logray]

I was wondering about the timing of the light. I measured the time it was lit which was approx. 1 sec. timed with my I-phone. It doesn't flash like any of these. It seemed like it was off for about 1 sec. also. Maybe I should time the off portion? I have to take a break from the car for a day or two of testing stuff to take care of my 89 yr. old Mom. I will be back. Thanks, Robert. P.S.- I would like to know if they mean the pointer to far right which it isn't but it seems that sensor may be the only thing left. thanks to logray for trying so hard to help me.

Those animated pictures in my post are just representations. The timing of them might not be 100% spot on to what you see in the car.

I would trust that the 1 second/1 hertz intervals (on or off) means the condition where that temp sensor is malfunctioning, which is what the documentation is telling us.

"4. Temperature sensor at water outlet faulty -- light flashes rapidly (1 Hz) ; pointer on the right"

This is just a guess, but it might be possible that both conditions don't have to be present in order for that light to flash at 1 second intervals. In other words EITHER the sensor could be malfunctioning AND/OR the pointer of the gauge could be all the way to the right.

Following our advice earlier, once you tackle the known, if it is still not fixed then you can start tackling the unknown. The unknown part could be the instrument cluster and/or gauge itself malfunctioning, etc.

Since the coolant temp sensor is inexpensive and easy to replace, much easier than the coolant level sensor to get to, especially after Loren's info - that would be my next step.

You will need to drain the coolant from the block because the water sensor tip does protrude into a water cavity. I recommend a 5 gallon home depot bucket for this job. To refill it is best done using a vacuum system, however others have been successful just following the manual bleed procedure. Look up Loren's post on adding a third radiator for those instructions.

[ALLSPEED]

Thanks

[ALLSPEED]

.jpg]Does anyone know what the grounding point is for in this photo? It is on the passenger side towards rear of car. It is right above what I believe is the oil pump. When I was chking the coolant temp. sender I can see this grounding point which has a bunch of oil and dirt on it. It is kind of hard to get to but might be related to my problem. Thanks, Robert. Edited September 23, 2011 by ALLSPEED

[logray]

If I remember right that is a ground point for bank 1 of cylinders (1-3) spark, fuel, etc. It is possible that the water temp sensor shares that ground... even if it is dirty and adding resistance, I'm not sure it would be enough to throw that light??? You might be onto something though with a wiring problem if it is not the sensor.

Going back to your efforts to isolate this problem.

Since you've unplugged the low coolant reservoir sensor and the light still flashes...

I am wondering that perhaps the reason why the light didn't flash or gauge move when you have the water temp sensor unplugged is because the dash is reading no resistance... meaning it's not going to budge... it needs to see resistance in order to move. You should be able to validate this by getting the temp readings from Durametric.

If you remove the sensor you should be able to "bench test" it. (edit: or I know it might be difficult to do, but perhaps measure the resistance of it while it is still installed in the engine). That is, take a multi-meter and measure the resistance of the sensor between two pins.

The test would be, measure ohms between ground pin and another pin on the sensor. On a good sensor it should be within a certain range.

Then put the sensor in hot tap water (or if still in car warm the car up a little, but not too hot) and it should again measure within a certain range.

The problem is I can't find the specs on this sensor quickly, which pins to test and how many ohms you should read out of it. Does anyone have this data somewhere? I will look at the wiring diagrams for the pins, but am stumped on the ohm ranges.

For example on a 944, it should read between 400-600 ohms at room temp. If it reads above that it is bad. At higher temps, it should read lower ohms, for example at 100 degrees F, warmish tap water it should read 280 ohms, etc. etc.

More examples...

A typical GM coolant sensor, for example, may have around 10,000 ohms resistance at 32 degrees F and drop to under 200 ohms when the engine is hot (200 degrees). A Ford coolant sensor, by comparison, may read 95,000 ohms at 32 degrees and drop to 2,300 ohms at 200 degrees.

Edited September 23, 2011 by logray

[logray]

Ok, the double "NTC" negative temperature coefficient thermistor (water temp sensor), does not appear to share that same ground point 11 that the bank 1 cylinders 1-3 coil packs use, that ground point you were asking about in your pic.

On the pins for the coolant temp sensor....

Pin 1 Black/orange goes to the DME pin 74 and am guessing it is 5V+.

Pin 4 Brown/pink goes to the DME and it is sensor ground.

Pin 3 Black/red and Pin 2 brown/orange go to the instrument cluster.

Black/red appears to be positive to the instrument cluster for the NTC H20 temp sensor. Brown/orange is analog ground for the instrument cluster.

So I think the pins you could ohm out on the sensor would be 1 (pos) + 4 (gnd) for the DME and perhaps also 2 (pos) + 3 (gnd) since it appears that the DME and instrument cluster each get their own reading from that sensor - hence the term double? right? (or double meaning perhaps dual range?)

I could use some help validating this BTW if anyone else is following this thread, also still need acceptable ohm ranges for the coolant sensor...

Edited September 23, 2011 by logray

[ALLSPEED]

I ran the car till the light started flashing and everything is like it was and then I unplugged the coolant Temp. sensor and the light kept blinking but the dash gauge went to zero. I took a video of before and after but the site said they were too large. One at 21meg and the other at 25 meg. I would like to post them. Is there a trick? or do I have to use some third party site which I don't belong to any. Thanks, Robert BTW- The started flashing at a little lower temp. this time. 96c with Durametric @ ECTS, 98c @ A/C hack, and 90c oil with Durametric. I want to post those videos. I also cleaned up that ground point before doing this.

Edited September 23, 2011 by ALLSPEED

[logray]

I ran the car till the light started flashing and everything is like it was and then I unplugged the coolant Temp. sensor and the light kept blinking but the dash gauge went to zero. I took a video of before and after but the site said they were too large. One at 21meg and the other at 25 meg. I would like to post them. Is there a trick? or do I have to use some third party site which I don't belong to any. Thanks, Robert

Try youtube.com... free and I think the limit is bigger than that.

[ALLSPEED]

Let me go there and figure it out.

[ALLSPEED]

This is before disconnecting-

and this is after I unplugged the temp. sensor

Edited September 23, 2011 by ALLSPEED

[coleta]

maybe Porsche made a typo and cause #4 is really for the coolant level sensor under the tank and not the temp sensor?

[ALLSPEED]

Well I don't know if this means anything but I unplugged the level senor and it still started flashing at the same temp. If you look at the video it sure doesn't look like it is flashing fast, does it?

[coleta]

Yes. It's flashing at 1hz, or once every second

[ALLSPEED]

With all the fine minds out there we should be able to beat this. I know lots of you are smarter than the dealers mechanics. HELP PLEASE

[ALLSPEED]

Logray- Any luck with some of those resistances for troubleshooting? FOR Loren-DO you still think it might be the level indicator or should I lean to the temp sensor even though it reads ok the flashing of the light seems to be in sync with that?

[logray]

I'm not having any luck coming up with the impedance stats for the water sensor, sorry... must be internal docs. Loren seems to be really good at coming up with that stuff... let's see if he has any ideas.

[ALLSPEED]

I am trying to measure them right now in case someone comes up with them. You have to be a contortionist. I will have to remove it to test it hot because their is too much exhaust around it.

[ALLSPEED]

Well the only thing for sure I have is the 1 hz. so I am going to try replacing the temp. sensor. There are a few other parts I want to order at the same time. Sunset is open tomorrow from 10 to 2.Is there someone who could help me or give me access to a program so I can get the correct name and number for the parts? Thanks, Robert.

Edited September 24, 2011 by ALLSPEED