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Registered
Join Date: Apr 2002
Location: New York
Posts: 123
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Thermo time switch tests
Still troubleshooting my 80 911 sc, starts right up but stumbles and runs rough til warm up, WUR tests ok,(I bought the books and the gauge package) took my thermo time switch off after reading a few searches and I get 0 ohms between terminals and 0 ohms from each terminal to ground, I guess i just need someone to confirm that it is bad, BTW which wire has B+ voltage and when?
I also know that the car is running rich, I am having a hard time finding a co gauge, (the cat is gone, bypass pipe in place) |
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04-16-2002, 02:25 PM
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Registered
Join Date: Dec 1999
Location: TX USA
Posts: 9,804
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Are you aware that the ThermoTime Switch only functions when the starter is engaged? It has no effect whatsoever on any running problem you are having! Perhaps the schematic below will clarify the matter ... the starter solenoid-ThermoTime Switch-Cold-Start Solenoid part of the circuit is the same as your car ...
What resistance range were you using to check the switch? From terminal 'G' to case ground is a heating element, and if your switch is really measuring zero Ohms on a 200 Ohm range, then it is indeed bad. Terminal 'W' to case ground is nomally a closed switch at room temperature ... when it opens is dependent on the markings on the switch body, and 45° C is typical. The chart below has some test values in it, but please note that the 911 Thermotime switches have round 'Faston' connectors, not those tiny 0.110" pins ... so those chart values can be used as a guide, but they aren't for the exact same switch! 
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Warren Hall, Jr. 1973 911S Targa ... 'Annie' 1968 340S Barracuda ... 'Rolling Thunder' Last edited by Early_S_Man; 04-16-2002 at 05:32 PM.. |
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04-16-2002, 05:28 PM
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Registered
Join Date: Apr 2002
Location: New York
Posts: 123
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I have the same diagrahm
Thank you, I was using the 1K scale on my ohm meter, my book has the same diagrahm, but with the round pins as you surmised, the previous posts regarding this unit suggest different readings than I received, you are right about the voltage only when cranking, I've overlooked something in the system, with the book and fuel gauge I've bench tested almost everything, I'm overlooking something, back to my readings, 0 ohms from each pin to ground and 0 ohms between the two i'm just wondering if it is giving a signal to the cold start valve to do it's thing. thnks again Pete
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04-16-2002, 10:30 PM
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