Fault Code for Level Control System

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Jun 20, 2013 | 01:09 PM

#11

aTOMic

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Joined: Feb 2012

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From: Moronville, Tennessee (Middle TN)

Quote:

Originally Posted by ltooz_a6_a8_q7

TOM,
just measure the resistance - thermistors come in all sizes - different by resistance, all it does is increase resistance when temperature rises - the system measure the resistance and calculate the temperature. NO rocket science stuff, even with AUDI. Remove the wire, put a thermistor out side dangling between the wires, you'll get it working.

Cheers,

Louis

I understand how thermistors work. Problem is, the only sensor I have is the one off my car, which is defoknackered (Scottish for futtup)

. It measures 461 ohms FWIW.
The real b1tch is you can't just look at the actual sensor value (AFAIK) in VCDS because it uses an algorithm to report the compressor temp. How do I know this (besides Audi SSP)? 'Cuz when I unplugged mine it shows a comp temp of, first 120C, then after ten hours, -20C, then it shows 40C -- and the whole time there is no sensor actually plugged into the car's wiring harness! You can even watch the comp temp increase as it runs (in VCDS) without the sensor connected (DANM ALGORITHMS!)! Gah, this thing will drive you INSANE if you try to figure it out! Like a WOMAN almost, and nearly as expensive! (Maybe this is why I love Audi so much)!

Jun 20, 2013 | 01:34 PM

#12

ltooz_a6_a8_q7

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Joined: Sep 2003

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From: Fremont, CA

Well, when the circuit is open, the A/D can't report correctly, that's why you get all these temps all over the map. Just short the 2 terminals to see how it reports, if it reports consistent, then the sensor is the problem. If it still reports all over the map, then it's the A/D circuit is bad. Open the board inside pump, find the A/D IC, replace it, I'm sure they still use through hole components, very easy to replace, not like surface mount like the one in the Head unit for the FBAS.

Cheers,

Louis

Jun 20, 2013 | 02:14 PM

#13

aTOMic

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Joined: Feb 2012

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From: Moronville, Tennessee (Middle TN)

Quote:

Originally Posted by ltooz_a6_a8_q7

...the A/D can't report correctly, that's why you get all these temps all over the map. Just short the 2 terminals to see how it reports, if it reports consistent, then the sensor is the problem. If it still reports all over the map, then it's the A/D circuit is bad. Open the board inside pump, find the A/D IC... through hole components, very easy to replace, not like surface mount like the one in the Head unit for the FBAS.

Cheers,

Louis

What what now?

Shorted, the temp reported on VCDS was 120C yesterday, with a "short to plus" error IIRC. I didn't leave it connected for long as this was before the algorithm revelation in my head...
You think there's a circuit board in the pump? The plot thickens...

BTW WTF is A/D & FBAS?

THX,
Tom

Jun 20, 2013 | 03:38 PM

#14

ltooz_a6_a8_q7

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From: Fremont, CA

Surface mount and through holes IC. Never mind.

Jun 20, 2013 | 05:08 PM

#15

mishar

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Joined: Nov 2010

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From: Vancouver, Canada

Quote:

Originally Posted by aTOMic*

Maybe this is why I love Audi so much!

This much?

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Jun 20, 2013 | 05:58 PM

#16

ltooz_a6_a8_q7

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Joined: Sep 2003

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From: Fremont, CA

Thermistor or digital temperature sensor (IC) must talk to the CPU or controller in digital. Thermistor is analog, so it needs Analog to Digital converter (A/D) to transfer the data to the CPU or controller whatever the case may be. I bet you the end of the sensor cable is where the board is inside the pump.
If the pump is dead, just open it up, slowly but surely, it can't be more dead unless you yank some wires off, even then, you can still reconnect and they should work.
If you can fix this temperature thing - you can buy all the broken pump and fix them.
To me, PUMP don't die - the electrical board components die.
Again, it's only my logic sine I'm in the electronics business.

Cheers and good luck,

Louis