Which plug on the back of the dash cluster holds the wires from the temp sender in the head and which wires are they in the plug? I want to determine that I am getting current to the gauge & if so perhaps temporarily wire in another gauge. Don't have time to fix it before leaving on a journey. I've never had any overheating issues but I don't like the idea of traveling and not knowing. TD

 

I believe my temp sensor itself is faulty. I am getting no continuity through the sensor regardless of engine temperature. Am I correct in assuming that there should be and that the resistance should change as the temperature changes? TD

 

sounds like you nailed it - plus its a cheap part!

 

The end of the temp sensor story: I opted for replacing the electronic sensor with a Bosch copper sensor in the head & with an analog gauge.

The gauge goes from 160 - 250 and seems to be accurate and very sensitive. I suppose that's good but it was rather disconcerting as I started on my 1,200 mi journey. The stock Volvo gauge just sat at the mid-point most all the time, showing only a slight deviation when climbing hills etc. This gauge shows that that slight deviation is actually from about 200 to 240. Even got to 250 on the long climb on I-84 out of Pendleton OR. After the journey I'm convinced that all is well and I'm just getting more detailed info to worry about! TD

 

240 is kinda high, that's over boiling point!

 

It only approaches that extreme on some of the serious grades encountered in the west on a hot day. Entire cooling system was restored a year ago so I'm sure it's behaving properly it's just that now I ACTUALLy know what the temp is. Ignorance is bliss to all those who rely only on "history" lights! TD

 

I guess as long as the cooling system is healthy it can handle it for short intervals. It'd make me nervous; I guess ignorance is bliss!