is this correct tts open test ?

[simsalabim]

Hello,

after verifying that there is around 23 ohms resistance across the G and W leads, I tried testing that the switch was opening once the temp rose above 45 C. I got 0 ohms whether the temp was cold or up to 150 F while bathing in boiling water ...

Am I testing this switch correctly/MM hookup for the "open switch" bench test ?

Thanks in advance ...

[timmy2]

You are testing the exact same point in the picture you posted. It should be zero, just like measuring across a penny.

You need to test from the G to W terminals on opposite sides.
Clip on G meter probe on W, or reverse.

Leave the clip where it is and put the meter on the round post on the other side. (left post in the picture)

[ischmitz]

both leads of the MM touch the same contact in your photo. put one left and one right on each round knob and try again.

[simsalabim]

I first tested across the G and W leads. That's when I got the 23 ohms when cold.

I want to test whether the ground to the csv is being disrupted once the switch reaches 112 F or above. Thereby shutting off power to the csv while cranking.

My understanding is that simply testing across the G and W leads tells me only what the bi-metal heating circuit is doing. Wrong ?

[timmy2]

Clip on the round terminal and meter probe on the threads that screw into the camshaft cover is what you want to do then.
Can't remember which round terminal, so try both.

[simsalabim]

Thanks Dennis.

Trying to do this test at my kitchen "bench". Keeping the switch above 112F might be a problem while in garage ... I thought the body of the switch itself was a suitable ground for this test ? Maybe I read a former post incorrectly ...

[simsalabim]

I should mention that when I DID test across the G and W posts when the temp was above 112 F, the resistance increased from the initial "cold" 23 ohms to around 37 ohms when temp was above 112 F. Does this sound like a faulty switch ?

Thanks again,
Bill

[boyt911sc]

Bill,

I did a show and tell demo how to test a TTS in the attached thread post #28:

Thermo Time Switch 1978 SC 3.0

Tony

[simsalabim]

Thanks so much Tony. I see that my resistance test was faulty and after using the threaded portion of the switch as my ground and repeating the test, the resistance was 0 when cold, and only rose to around 97 ohms after heating ...

I am assuming a bad tts at this time. If this assumption is correct, I am wondering where I might find a good used one ?

I appreciate the heads up on your tutorial. My initial forum search did not reveal the page it was located on. Thanks again.

Bill

[boyt911sc]

Bill,

You are doing the test wrong. Measure the resistance between terminal G and the body. If the switch is closed, terminal G and terminal W would be same as using the body.

What you need to know is if terminal W is open above 54°C (113°F) and close below this temperature. Use a continuity tester or a test light for convenient testing. You could observe the light or hear the beep for continuity test. PM sent for the procedure.

Tony