We just bought this blazer and have practically rebuilt the whole thing. We replaced the thermostat and both temperature sensors.

Now that we have it all put together it is running fine, the check engine light isn't on......

But as soon as I crank it up the temperature gauge maxes out and then the check gauges light comes on. The engine doesn't seem to be running hot. We have no idea what could be causing this to happen.

Thanks for your help!

 

Sounds like your temp wire is shorting to ground. The hotter the temp sensor gets the lower the resistance and the gauge registers this. Hence your wire is probably grounding out somewhere (it thinks it's hot - little to no resistance). This is what I would sheck first unless you bought a bad sensor. You can check it bit most people get burned when they do. Engine cold, wire disconnected, check resistance from sensor to ground. Start engine and resistance should drop as the engine heats up. Check the wire first.