Great question.
The probe lives in the offside side of the front bumper. Mine both read about 10 deg. warmer than actual. Be great to change one from say a Ford?

 

a generic electronics component that changes resistance (thermocouple) can be located, i can come up with it based on test resistance measurements and my car temp gauge, but I hoped someone else had already done this work?

Anyone found a suitable replacement?

 

Sorry I can't help you directly on this. I have never seen anyone mention a Don't forget that you can often find out what you're looking to determine just by examining the markings on the original item itself (if they have survived the elements).

I also don't know how much of the attached may be of use, as things do change over the years, but certain stuff seems to remain quite static.

 

I'm still fairly certain that on the Turbo R and Continental R it lives in the right side (offside) bumper as I've removed both bumpers. It's just a bit of shrink wrapped wire that goes into a plastic hole. Both gauges read over optimistic on mine. Suppose one could fudge the gauges but not me.

 

The sensor in the front right bumper on my LHD 89 Spur is NOT the one that drives the display. I have no idea where it goes.

If anyone has a working thermocouple for the digital display they can measure resistance at different temperatures between 40degF and about 90degF (maybe 3-4 data points) that would be helpful in me finding a thermocouple with a matching resistance response.

 

Issue resolved.

Digikey.com (major electronics supplier) provides a bulb/bead-type thermistor with very close resistance values to the original factory temperature termistor.

Part # BC2465-ND on their website works excellent. It's $3.01 instead of $100something.

If you want the version that's in a small barrel shape, check part # BC2468-ND

Tested and working great! Take care!
-Brendan

 

Brendan,

Thanks for the part information. Unless I missed it you've never mentioned where that thermocouple was actually located on your car. If you wouldn't mind, would you please share? This information is equally valuable for future readers (and I'm curious).

 

Well, as a North American car I thought from the diagrams it was in the front right corner. I found a temp sensor there, but it was NOT the one connected to the temperature display nor ICE indicator.

Where is the one that goes to the ICE & temp display on the screen? I'm not sure. The wire is found in the black cover just aft of the suspension and shock tower.... a round connector - the wire leads out towards the front of the car and disappears down through a grommet behind the AC dryer - I dropped a panel below the car and couldn't' see it easily so in the interest of time I didn't keep disassembling. Instead I cut the wire, near the coolant tank and fed the thermocouple sensor bulb down into a whole in the fender, which should be relatively isolated from engine heat - at least within the relative range of the accuracy of the thermocouple and my needs.

Sorry I couldn't be more specific, I wanted to 'do it right' but just could never find it like the documentation showed in the bumper.

-Brendan

 

It usually comes out of a rubber grommet behind the left front 1/4 bumper. Just pushed through as an 'interference fit'.

Paint shops love to just pull them in and tie them up somewhere. Often filling the hole if there's any accident damage.

Earlier cars have them pushed into round blocks bolted to the bottom of the main bumper bar.

 

Mine had the front right side sensor (don't know what it does?) in a round block, but that was NOT connected to my temp display. Maybe if I had pulled further on that rubber grommet I'd have found it. But I'm still curious what that one is in the aluminum block in the front right bumper. It terminated in the same round connector style under the plate near the shock tower on the front right corner.

 

Does the climate control unit have an outside temp probe? (Probably not as the SY doesn't, and I think the SZ is still using the same system.)

 

Jeff. The Shadows hid theirs behind the right rear bumper end caps. A flat plate later replaced by a heat shrunk one.

 

I wondered that at first, but why would the climate control system care out the outside air temp at all?

 

Because when the temperature is above freezing (or somewhere not all that much above freezing) the compressor is active in order to dehumidify air *before* it heats it up. This has never made any sense to me, since cold air has little humidity to begin with and even less (relative) when it gets heated, but I do believe that operational quirk carried over to the SZ era cars. I tried doing a quick search in IETIS to confirm what "normal operation" is, but I can't come up with the magic search terms to get that to show up.

 

Hey Brendan, just curious as to what problem you were solving with your work. For me, my temperature gauge reads laughably high, which makes me think that it is in the radiator shroud as Brian's diagram shows. However, I see a sensor in my bumper as others have noticed. With regards to my ICE reading, it is a very scared fellow, always letting me know to watch out for ice even though it's about 9 degrees celsius outside. I scanned the wiring diagrams in detail but couldn't come up with anything conclusive.

 

Shaun & others wanting to test their unit:

Mine was intermittent. Here's how you isolate where your issue is:

If you have the black plastic 'digital' self contained temperature display, I can only say for sure on an American LHD car it goes out to a connector that's a round shape plug sitting under the black flat lid near the shock tower on the left side of the car. Pull that plastic lid, and remove the Headlamp Controller brick (not easy).

Unplug the connector. It pulls firmly straight apart (rubberized gasket kinda thing).

On the female connector closest to the windscreen (going back towards the dash) install a 2.2k ohm resistor with the ignition off between two of the three pins. Just jam them in the female pins. From memory it's black purple and black but if you look in the service manuals its clear that the third lead is not used, just look carefully at the plug one of the wires does not continue through the connector, so it's the unused one. Turn on the ignition and you should read 68degF (20degC) with that resistor in place.

Another test resistance is 10k, it should read 21degF (-6 degC), one more: 1.4k would be 96degF (35.5degC). How do i know these values? Just from testing - i needed to build a dataset so i could choose the right thermistor for the replacement.

I would advise install a test resistor as described above and drive around for a few weeks. If the temperature numbers stay rock steady on those known resistance figures, then you know the thermistor is your problem and can replace it with the part # I provided above.

Good luck!
-Brendan

 

Air con oat sensor is on the right on UK cars. I doubt that would change on LHD cars.

Why?

If you're driving into a hot area or up a cold mountain, the air con likes to know so it can adjust accordingly.

There us also the solar sensor on the top roll. . . If it gets lots off solar heating it will lower it's output temp slightly.

If your outside temp is correct when the car has been sitting for 24 hours but rises to a very high reading as the engine warms up, chances are it has been pulled into the inner wing or engine bay and is measuring engine bay temperature instead.

The sensor location did move around depending on chassis number.

 

Brian, the sensor for this is in the evaporator box. Sensor (switch) is in the bulkhead near the transmission dipstick. Slightly higher and central.

Because when the temperature is above freezing (or somewhere not all that much above freezing) the compressor is active in order to dehumidify air *before* it heats it up. This has never made any sense to me, since cold air has little humidity to begin with and even less (relative) when it gets heated, but I do believe that operational quirk