???Coolant Temperature Sending Unit???

[maynardogle]

Your problem is the reason most older vehicles end up with an aftermarket gauge pack. I hate staring at an OEM gauge and wondering if it is right or wrong. Stewart-Warner i still around for a reason. That being said, make sure your block, frame and cab all have good clean grounding straps. Then look at the sensor, and maybe swap it. If that doesn’t fix it, it means the gauge or voltage regulator for gauges is bad.