Temperature gauge reads too hot

[masospaghetti]

My temperature gauge when completely cold almost reads right in the middle of the range (warm). When actually warm, the needle is dancing on the "H" and my check gages light keeps going on and off. I've replaced the sender with no difference.

1. Any ideas what the culprit is and what I can do to fix it?
2. Does the sender resistance increase with temperature or decrease?

Thanks all...96 XLT 5.0.

 

[rs2k]

Resistance from the sender decreases with heat. http://oldfuelinjection.com/?p=28

I noticed my 302 has two temp senders. Did you replace them both?

A bad sender or a bad connection between the sensor and the PCM could cause that symptom.

 

[masospaghetti]

The two pin connector provides ECM data, the single pin connector drives the gauge only. At least, that is my assumption (that's how it works on the GM vehicles i'm used to).

I haven't replaced the two pin connector but there's no indication that the ECM is getting bad data, just the gauge.

 

[crunchie_frog]

I had this happen on a Ford Escort and it ended up being the gauge itself in the instrument cluster. I replaced the instrument cluster to get it to read correctly.

 

[masospaghetti]

Is the gauge portion of the instrument cluster replaceable without replacing the entire cluster?

I don't want to have a mileage discrepancy.

 

[crunchie_frog]

Is the gauge portion of the instrument cluster replaceable without replacing the entire cluster?

I don't want to have a mileage discrepancy.

I do not know for sure, but I do not think so. You can go to your local pull a part and try to take a cluster apart and see.

 

[koda2000]

much easier to replace the entire cluster, but i'd try replacing the sender first. replacing the cluster is a lot of work and it may not be your problem.

tip: if you do replace the cluster, do yourself a favor and put all new bulbs in the replacement. you don't want to have to do this job twice.

 

[masospaghetti]

I tried replacing my sender already. No change there.

Can the odometer be easily changed with the cluster out of the car?

 

[koda2000]

I tried replacing my sender already. No change there.

Can the odometer be easily changed with the cluster out of the car?

no. and that's illegal to do.

 

[deweyville65]

I would opt for a mechanical aftermarket gauge if at all possible. I know these newer vehicles don't leave much room for aftermarket gauges. But if I have to replace any faulty gauge, I will find a way. pillar mount anyone?

 

[koda2000]

I would opt for a mechanical aftermarket gauge if at all possible. I know these newer vehicles don't leave much room for aftermarket gauges. But if I have to replace any faulty gauge, I will find a way. pillar mount anyone?

you got my vote. a real gauge on a pillar mount. imagine knowing what your water temp really is. while your at it, how about a real voltage and/or oil pressure gauge in that pod?

 

[crunchie_frog]

I do not think the odometer is easily removed and replaced, but again I not sure. While Koda is right, the cluster is not the easiest thing to pull it is about a 30 min job. All you need is a 7 mm socket and 11 mm and some extensions. Start by removing the two bolts holding the plastic panel at the bottom of the panel, then the two bolts holding the engine compartment pull latch. You should be able to pull the panel after that. Then remove the metal panel behind that there are 5 screws for that. There are 2 screws you can now see for the upper plastic panel at the bottom of the panel. There are 3 screws up under the dash right in front of the cluster to remove. Now remove the two screws on the black bezel that surrounds the radio and temp controls and carefully pull/ pry out the black bezel. Now the top plastic panel piece you should be able to wiggle it out. I think there is an electrcal connectiYou also will have to separate the driver side vent from the top plastic panel. Now you can see the 4 screws that hold the instrument cluster at each corner. Remove those and you will be able to back out the cluster far enough to disconnect the electrical connectors.

 

[rs2k]

Changing the odo is harder than changing out the bad gauge:

http://www.therangerstation.com/forums/showthread.php?t=45192

 

[delexploder]

I do not think the odometer is easily removed and replaced, but again I not sure. While Koda is right, the cluster is not the easiest thing to pull it is about a 30 min job. All you need is a 7 mm socket and 11 mm and some extensions. Start by removing the two bolts holding the plastic panel at the bottom of the panel, then the two bolts holding the engine compartment pull latch. You should be able to pull the panel after that. Then remove the metal panel behind that there are 5 screws for that. There are 2 screws you can now see for the upper plastic panel at the bottom of the panel. There are 3 screws up under the dash right in front of the cluster to remove. Now remove the two screws on the black bezel that surrounds the radio and temp controls and carefully pull/ pry out the black bezel. Now the top plastic panel piece you should be able to wiggle it out. I think there is an electrcal connectiYou also will have to separate the driver side vent from the top plastic panel. Now you can see the 4 screws that hold the instrument cluster at each corner. Remove those and you will be able to back out the cluster far enough to disconnect the electrical connectors.

Dont forget the 5.5 mm bolt in the bottom of the column for the shift indicator and the string from it is on a hook, if not you will break it,

 

[koda2000]

Dont forget the 5.5 mm bolt in the bottom of the column for the shift indicator and the string from it is on a hook, if not you will break it,

yeah, you don't want to break the PRNDL wire/string. if you're familiar with removing the cluster you can do it in about 30 min, but a first-timer better add another 20-30 mins for head-scratching.

 

[masospaghetti]

Yeah, i've removed the cluster a few times, but not on an automatic. Not familar with the gear position indicator "string/wire".

From the link it looks like the temperature gauge is pretty easy to replace once the cluster is out. I was also considering installing a 10-ohm resistor in series with the temperature sender - this would bring the reading down enough to avoid tripping the "check gages" light.

 

[koda2000]

the string/wire is really easy to remove from the shift lever. it just has a loop on the end of it which fits over a hook. then you remove the 5mm bolt to take it loose and you can snake it out with the cluster. a side benefit is that when you put it back you can adjust it so that the needle actually points at the right gear...

 

[98ExplorerGuy]

My temperature gauge when completely cold almost reads right in the middle of the range (warm). When actually warm, the needle is dancing on the "H" and my check gages light keeps going on and off. I've replaced the sender with no difference.

1. Any ideas what the culprit is and what I can do to fix it?
2. Does the sender resistance increase with temperature or decrease?

Thanks all...96 XLT 5.0.

Just to clarify, are you saying that if you turn the ignition to on with a stone-cold (car has sat overnight, for example) engine, the gage rises immediately to the halfway mark?

Or, are you saying that after just a few minutes of running the gage reads mid- to hot even though you get cold air from the heating system?

If the latter, then you may simply have a bad thermostat which is not opening allowing engine coolant to exchange with radiator coolant. The engine reaches operating temperature quickly and even overheats while the rest of the coolant in the system stays cold.

This is exactly what would happen with my 98 Explorer; the thermostat would eventually open and everything would work itself out. Until... the thermostat finally failed and refused to open which caused all sorts of problems.

 

[masospaghetti]

Yeah, even with a stone cold engine, the gauge reads at about the halfway mark.

When I got the truck, the thermostat WAS stuck closed also (and I thought this was my only problem).

 

[rs2k]

I had a bad thermostat kill a temp gauge on an old Impala I used to own. The car over heated once when the therostat stuck closed and the gauge read too high. After I replaced the thermostat the gauge did the same thing yours is doing. Half temp when cold and over the top when warm. The car was a beater though. I just installed a cheap add on gauge instead of trying to repair the one in the dash.