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By checkmate1996
#68231
Hey all - I am troubleshooting my outside temperature ring sensor. The only ohm reading I’m getting is 1.776 kohm. Whether I heat it up or ambient temp. It suggests to me that something is wrong. My under standing is the high side is 900 ohms and low side is 400 ohms.

My process consisted of disconnecting the ring from the harness and put my ohm meter directly on the wires in the of the ring connector with the thermosistor.

Thoughts?
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By worf
#68238
You've got one multimeter probe on the male pin in the connector to the 'ring' and one probe on the female connector right?

And with a change in temperature you see no resistance change at all?

Using a heat gun or something?

Pins are clean and reasonably free of corrosion?

Yup. It's dead Jim.
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By checkmate1996
#68482
So just to confirm my process and results:

- Black Dmm probe to female end of connector in wheel well
- ran another wire from other open female connector to male side of ring temp sensor
- ran another wire out from the other male ring temp sensor to my red probe; this completes circuit

Ohm measurements
Slider all the way to cold - 1.456 kohms
Slider all the way to hot - -4.5 kohms
Slider in the middle - roughly 0.01 kohms

If I remove temp ring from circuit and just measure the female harness side-
Measurements stay roughly the same except for cold. They show .600 kohms

This all looks off to me. It seems the ring sensor is an issue but feels like problems in other places....
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By worf
#68505
checkmate1996 wrote: Tue Mar 23, 2021 5:26 pm So just to confirm my process and results:
Start over. What are you trying to test? The outside temperature sender or the HVAC settings motor?
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By checkmate1996
#68635
Ok here's what got everything started. I was evaluating my Heater control valve and noticed that it's always open on either full hot or cold.....BUT....closes when you slide to the ALL OPEN rectangle block on the slider. So I'm trying to figure out what could be causing that...

That being said, I've tested that I have the appropriate vacuum and the heater valve actuator is working but only on the one setting....
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By checkmate1996
#68652
OK - I've just found a very nice testing procedure in the WSM Gray Manual section 87 pages 110-119. I'm going to start there first and report back...
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By worf
#68665
checkmate1996 wrote: Wed Mar 24, 2021 11:47 am OK - I've just found a very nice testing procedure in the WSM Gray Manual section 87 pages 110-119. I'm going to start there first and report back...
Great! I was just about to post that you should start with WSM 87-108.

Based upon your previous post: if the hot water valve closes with the temperature slider all the way to the left and is otherwise open then the system is operating as designed when either the interior or exterior temperature sender is KIA.

If the above is true and is not a misunderstanding of what you wrote, then I would indeed start with Ohm-ing out the exterior temperature sender as that is the usual culprit when automatic temperature control goes South.

The sender is a resistance-based "sender" so to test it you test only at the sender's plug. You do not need to 'complete the circuit' with the settings motor / temperature operating switch.

On the sender-side plug you attach your multimeter probes to the connectors pins. One to the male and one to the female pin. Ignore the body-harness connector. Your MM completes the circuit. With your MM set to resistance, measure the resistance and then apply heat and/or ice and see if the resistance changes. If not, it's dead. If it does change then you need to check the resistance range.

This is the general range:
~ 933 ohms at 0 °C
~588 ohms at 20 °C
~457 ohms at 30 °C
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By Crumpler
#68671
We are talking about sensor in the alternator cooling hose right?

Why did the engineers but it there?
Is the answer “why not”?
This is the only car I’ve taken apart and put back together. Is it a common location for exterior temp senders?
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By checkmate1996
#68690
We are talking about sensor in the alternator cooling hose right? Yes
Why did the engineers but it there? Great question. (Similar after thought to where they put the water pump for hood nozzles.)
Is the answer “why not”?
This is the only car I’ve taken apart and put back together. Is it a common location for exterior temp senders? Not sure.
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