Temperature gauge not working

the most expensive part of 3 possible replaced 2 times.
wow.
the sensor or the wires (end to end) are bad. (just one gauge fails?)
the service manual covers how this work.

I guess you meant the IP cluster engine temperature meter reads wrong and the engine thermostat is not bad, 23 years old and thermostats have design life of 7 years../
a scan tool set to scan PID, ECT sensor tells what coolant is doing.
189f to 213F is spec, temp range

the gauge coolant temp has:

Water Temperature Indicator Sender Unit
When the engine temperature is low, the resistance of the water temperature indicator sender unit (10884) is high, thus restricting the flow of current through the gauge and moving the pointer only a short distance. As the temperature of the coolant increases, the resistance decreases, allowing more current to flow through the gauge and resulting in a corresponding movement of the pointer.

these year trucks the gauge sender is not the ECU ECT sensor
and may be single wire sender.. try mostly fail this old, not the gauge
the wire on the sender can rust or even fall off.

the temperature sensor and the gauge sender are two different units
the wire to the temp sender could be broken or fallen of the sender
that wire has power to it and needs to be connected to the sender so that the variable resistance in the sender can work the gauge

possible low coolant level
loose wire on sender unit
faulty sender unit
take the wire of the sender unit and put it to ground
with the ignition switch on , the gauge should go straight to hot
that indicates the circuit and gauge is operational which leaves the coolant level and sender unit

If you replaced the SENSOR and not the gauge SENDER, there's your answer.

The SENSOR sends the computer (ECM, PCM, ECU, etc.) the engine temp so it can make the adjustments to the fuel, timing etc.

The gauge SENDER makes the gauge read what temperature the engine coolant is.

Hope the helps.

The sensor has nothing to do with the temperature gauge. That is controlled by a sender unit (1 wire) that changes the electrical resistance to current passing through the gauge. Remove the wire from the sender unit and earth it out. and if you have power through the gauge it will immediately go to hot. IF it does then replace the sender unit.

simplify. you just were in the engine compartment... did something get disturbed, unplugged, look at the temp sender and the oil sender, they have been the most likely causes of concerns of this type since electric indicators replaced gauges years ago. does your system have a tripminder or indicator for changing the oil? does it get a reset during the service? if yours has that there may be a mode that its in...but not fully reset.. then theres a question about..does your body control ecu have a self test mode? or your powertrain control? these can be read for codes for free as a preliminary check at a local parts store.

From what I just read about your vehicle,it has a history problem with the gauge,may be the coolant temperature sender or the gauge,it says the whole cluster will have to be changed to be fixed if the gauge is bad,found some forums and all had gauge problems.Right above the coolant temperature sensor is the coolant temperature sender,this is what sends the temperature to your gauge,the sensor sends a signal to the computer,they may have replaced the wrong one,here's a link to the sensor,the hole above it is where the sender goes,it's a one prong part,the sensor is a 2 prong part.A lot of people don't know that there are 2 types of coolant temperature gauge sending unit and sensor.

touch the lead that connected to the sender to the ground to see if the gauge move. if the gauge move, then the problem is in the sender. if the gauge does not move then the problem is in the gauge or the wiring

Find and check the temperature gauge sensor 'sender' unit on the engine.
To test:-
- if you ground the wire connected to the sender the gauge should go to full scale high,
- open circuit the gauge should read zero (nil deflection).
If above test ok, replace the temperature sender unit with correctly specified item.

most sender to gauge are on the thero housing, if the therostat housing has one or two senders on it, one it temp and one controls fan, see if wires on sensors are hooked up, thanks robert b.