My temp gauge stays right on the line of normal and cold. I just replaced the thermostat for the coolant. I don't know if this is normal or not. Is my temp gauge broken? It moves from cold when it starts to the line in-between normal and cold after I run it on the highway. It never goes past that really.

 

Fords use a 192 or 195degF thermostat, that should register just below 1/2 on the Ford temp gauge, 205deg is about 1/2, climbing a hill should run temp up to 215-220, so above 1/2 way.

If you run a 180degF thermostat then it will, of course, show colder on gauge, MPG will also be lower and oil won't stay as clean

 

I just changed the thermostat and I made sure to use a 192 I believe. Gauge registers just barely normal. Is there a sensor that goes bad?

 

Sender, not sensor

Need year of Ranger, assuming 4.0l engine?

 

1993 4.0L

 

Sender will be just above thermostat housing on lower intake.
There will be two of them that look similar.

ECT(engine coolant temp) SENSOR, only used by the computer, it always has 2 wires connected

ECT SENDER, only used for dash board temp gauge, only has 1 wire on a 1993 Ranger

Cold engine
Remove the 1 wire connector on the SENDER, turn on the key
Gauge should either stay below COLD OR move all the way up to HOT
Now put a jumper wire on that 1 wire to SENDER and Ground the jumper wire

temp gauge should now do opposite of above, with sender wire Grounded gauge should show above HOT or below COLD, opposite of when it was ungrounded

That tests the gauge and wire, if they pass the above test then replace the sender

If gauge doesn't swing the full range then could be wire or gauge issue.

Auto parts store guys will almost ALWAYS bring you an ECT sensor first time around.
Have them look it up again and stress you need a SENDER, lol.

And just as a heads up, a SENDER uses it's threads as the Ground to complete the circuit, so always leave some bare threads at the bottom of the sender, do NOT put sealing tape on the lower threads.