I heard about your site on Market Watch and have a question regarding my Chevy Blazer with 122,000 miles on it.
The “Check Gauges” light comes on and my temp gauge spikes on occasion. I turn the heater on to maximum and the needle goes back to the middle of the gauge. It never actually overheats and I am not losing or smelling antifreeze ( it was replaced 2 years ago with a new radiator ). My fuel indicator also bounces back and forth as this is taking place, so I’m wondering if it’s a sensor problem or actually an overheating problem .
Any ideas ?
Thank you .
Thanks for your email.
Are you SURE the engine is not overheating or running hot? Wonder why the temp gauge DOES come down when you run the heater, which is taking some heat from the cooling system and running it through the heater core in the dash….which is basically just a small radiator.
I would be a little suspect that the engine IS running hot. Make sure the radiator is full of coolant , and if low you should get a cooling system pressure test to see where the leak is and repair it. Rule out the possibility that the engine is running too hot at times and although not boiling over still its hot enough to alert the dash gauges.
If you are sure the engine is not overheating or running hot, I would look at the alternator. I have seen many internal alternator problems cause strange dash gauge issues. The alternator can still be charging the battery and still have an internal problem that could cause the gauges to freak out.
Also dirty or loose battery cables can cause dash gauge problems, so rule that out as well.
Your mechanic should be able to check the alternator to make sure its not overcharging or has an internal issue, like a diode trio or voltage regulator problem.
Simple alternator testing video you can do yourself
Lastly, I have replaced a few dashboard clusters with used gauges from a junk yard. You could have an internal dashboard problem, but rule out the other stuff first before we put blame there.
The dashboard cluster (usually sold in 1 piece, but available at junkyards too)
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