1970 Lemans temp sending unit issue

[cmoore1953]

OK, another curve ball. I replaced the stock idiot lights in my 70 Lemans with a retro gauge cluster purchased from OPG that match stock speedo. The new gauges come with a 1 lead temp sensor. The existing temp sensor is a 3 lead sensor but only 2 wires are connected to it. Once the new gauges were installed we left the existing sensor in place and the temp gauge will initially go up and then drop back down even after engine is warmed up. So, the question was how to change the existing 3 lead sensor which has 2 wires connected to a 1 lead sensor and make it work. I called OPG and they didn't have a solution so I called AMES and they have a wire harness that jumps a 3 lead sensor and you have to install a 1 lead sensor in another temp port and then it connects to the wiring going to the temp gauge. A simple fix except I only have 2 wires connected to the existing 3 lead sensor and don't know where the other wire is or should be connected. Any and all help is appreciated as always.

By the way, your post on removing and replacing the gauges was extremely helpful. Thanks!!

 

[EaOutlaw]

Did you ever pick up a service manual, in there you will find the specific wiring diagrams.

With the diagram you will know where each wire comes from and goes to. it should also show you connector locations with pin locations.

 

[melsg5]

Ames lists M192 a single terminal sensor as the correct one for gauges. Did you look in the Chassis Service manual wiring diagram to determine what the purpose for the two wires are in the existing harness? Did you try using a test light or voltmeter to determine which of the two wires is hot? The hot wire would connect to the single terminal sensor.

 

[cmoore1953]

Thanks for the input and suggestions. I do have a service manual. The problem is the previous owner modified the wiring harness so I called AMES and their tech rep walked me through the wiring harness jump from the existing sensor to the new single terminal sensor and everything works.

Again, thanks for the input and suggestions. You guys are spot on!

______________________________

 

[melsg5]

glad to hear you got it straightened out