[s-cars] temp gauge hokey pokey

Vincent Frégeac vfregeac at sympatico.ca
Thu Dec 5 19:50:39 EST 2002


After all this post about changing this or that, I'll add another way of
thinking: Do not use any tool!
- Start your car,
- On your heater control, press Recirculate and Up Arrow at the same
- You should see 01c instead of the temperature, which means Channel 1
of your Heater Control ODB
- Press the Temperature "+" until you see 51c, channel 51
- Press the Recirculate again
and Shazzam, here is your coolant temperature, in Celsius, courtesy of
the ODB of the Heater Control and Rich who pointed me to the very
interesting www.12v.org/maint/cc.html

If the temp goes down on the Heater Control when you're cruising and go
up in heavy traffic, your T-Stat is shot. If your temp stays rock
stable, like mine, it's either your gauge or your MFTS. Usually a
MalFunctioning Temp Sender will intermittently display the right
temperature or fall down to 0, but who knows. Then, you can apply a
latter Rich's suggestion, plug an electrical resistance in the MFTS
plug. Rich suggested 40 ohms but the Bentley says 580 ohms for the 3
thick marks area and 58 ohms for the 90-110C area. You should see a
group of two small dot on your gauge in the 580 ohms and 58 ohms area
(May be it's only on CAN spec gauge). Anyway, according to the Bentley,
40 ohms should send your gauge way over 90C but I've no BTDT and it
seems Rich have played a bit with this problem, so take what Bentley
says with a grain of salt. I would have been happy to double-check the
right resistance on my S6 if I was not suspecting my gauge to be way out
of spec.

May be a lister with a proper temp gauge could do it for us. Anyone?

If your temp gauge react to fixed resistance the way it should, it seems
the MFTS have just invented another mode of failure. If the gauge gives
wrong readings, you can either change your gauge or wait until I pull
out my soldering iron and try to fix my gauge. My quest for 90C have
started several years, several Audis, several T-stats and several MFTSs
ago but may be the gauge saga will be the solution of this never ending

Good luck,


-----Message d'origine-----
De : s-car-list-admin at audifans.com
[mailto:s-car-list-admin at audifans.com] De la part de Paul Krasusky
Envoyé : 5 décembre 2002 08:07
À : 's-car-list'
Objet : [s-cars] temp gauge hokey pokey


With all the recent temp gauge, Tstat, multiMalfunctioning temp switch
of late, gee, thanks guys, apparently you sent out some sort of curse.
Either that or Pizzo somehow drove my car last night.  Dunno.

My temp gauge acted hokey this morning.  First noticed it a few nights
I ran it pretty hard the last 2 miles or so of my 22 mile commute, and
I came off the off ramp, I noted the gauge had buried down low.  Came
up after a second, I dismissed it.

Today I started and ran it in garage with heat on Auto / Hi for say 3-5
minutes while I fluffed my quaff, ironed my skirt, and did my nails.
been in the low 20s here and I wanted 'some' heat.  Get on highway, I'm
getting some heat as usual.  Get up to 4 or so lines on gauge (Major
Technical Term), oil's up, so I whomp it for a spirited burst.  Back off
see temp gauge has dropped to 2-3 lines.  WTF?  Heat's still coming out
normal (not much but some, still only few miles down road so far).

Figuring I'm sucking away the engine heat with the heater, I turn it
Gauge slowly recovers to a bit under the normal "5th line".  Turn heat
on.  Gauge falls to a tick over the 4th line (More Major Tech Terms).
that way for remainder of commute, heat is nice and toasty now.

Get to sunny Hartford, come to stop, gauge falls back toward 3rd line.
Slowly returns to just over 4th.

Sssoooooooooooooo, aside from being an excuse to finally do that coolant
flush I've been meaning to do, what could I be looking at here?  I'm
guessing either Tstat or M(M)TS.  What the heck kind of fun repair is
supposed to be?  What a jip...  no possible "angle" to play for some
upgrade of sorts.

Anyway, please, start laughing at me, I would, and let me know what you
think (aside from that I'm a tool, that's well established).


CT "big snowstorm today!" yeah, sure, uh huh
'95 //S6 needs Pizzo's lugs for snows to go on, oh well, and with
questionable heat situation
'58 TR3A heater was optional, mine don't have it
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