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Water temp

haze_pa

By haze_pa
in Ask A GM Technician

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haze_pa Enthusiast

haze_pa

Posted
Posted

Guess I posted this in the wrong section before so I'll try again here.

 

I have a '94 K1500. Awhile back I lost my water temp indication. I tried a temp bulb twice with no luck. Is my next step to replace the instrument cluster or reset the computer somehow?

 

I tried a code reader too. All I got from that was a fuel problem code that happened as a result of losing the water temp indication.

 

Any help would be appreciated. Thanks, Rich :flag:

GM-Tech Senior Enthusiast

GM-Tech

Posted
Posted
I have a '94 K1500. Awhile back I lost my water temp indication. I tried a temp bulb twice with no luck. Is my next step to replace the instrument cluster or reset the computer somehow?

 

 

Are you saying the light doesn't light up during the bulb check on startup? I'll have to look at a schematic tomorrow, but that's done through the ignition switch, I believe.

haze_pa Enthusiast

haze_pa

Posted
  • Author
Posted

No! I'm saying as the truck warms up, the needle that would tell me what the water temperature is, has not moved. And hasn't moved for some time now. :gmc:

GM-Tech Senior Enthusiast

GM-Tech

Posted
Posted
No! I'm saying as the truck warms up, the needle that would tell me what the water temperature is, has not moved.

 

Hmmm, you said you tried a "bulb" twice, that's why I asked. Could be an open between the temp sending unit and the cluster. I don't recall the cluster getting temperature information via the PCM's coolant sensor in the intake in '94, but a separate sensor in the cylinder head.

MAXX_EXC Enthusiast

MAXX_EXC

Posted
Posted

To GM-Tech:

 

Thanks for being patient to people who fail to provide necessary details and then become impatient when asked for the information.

 

Your Help is Much Appreciated though it may not always be expressed!

MAXX

:banghead:

:cheers:

 

 

No! I'm saying as the truck warms up, the needle that would tell me what the water temperature is, has not moved.

 

Hmmm, you said you tried a "bulb" twice, that's why I asked. Could be an open between the temp sending unit and the cluster. I don't recall the cluster getting temperature information via the PCM's coolant sensor in the intake in '94, but a separate sensor in the cylinder head.

 

 

 

 

  • 3 weeks later...
haze_pa Enthusiast

haze_pa

Posted
  • Author
Posted

To Maxx_exc, your response to my water temp problem was neither helpful nor appreciated. I don't need you to intervene with what you perceive to be impatience on my part. In my original post I did say that "any HELP would be appreciated".

 

I did however use "temp bulb" when I probably should have used "sensor" but I don't believe this truck has a lightbulb to tell me what my water temperature is.

 

Now to press on with further details... I had a "conehead" (avionics technician) at work check out the instrument cluster. He tells me it's working properly.

 

I re-installed the instrument cluster and now the water temp needle will peg itself when I start the truck but then drops back down and stays there as the truck warms up. I'm going to test the "sensor" with my multimeter and see if it is working. Just because it was new when I installed it, doesn't mean it's working now.

 

If anybody has any other suggestions (on the water temp problem only) I would appreciate the input. Rich

GM-Tech Senior Enthusiast

GM-Tech

Posted
Posted
I re-installed the instrument cluster and now the water temp needle will peg itself when I start the truck but then drops back down and stays there as the truck warms up.

 

This is probably not all that abnormal. The gauge does swing towards the hot side when in the crank position. If it flies over there instantly, the damping mechanism in the gauge is gone. Not uncommon in older trucks.

 

Check the resistance of the sending unit. Wouldn't be the first time I saw a sender for a light that was put in a vehicle with a gauge. That type of sender is open all the time until the engine overheats. An open sensor or very high resistance causes a low reading.

  • 7 months later...
haze_pa Enthusiast

haze_pa

Posted
  • Author
Posted

OK! Guess I'll have to answer this myself.

 

According to Chevy's "official" manual there are only three things that can go wrong with water temperature indication....

 

The sensor (temp bulb) is bad, the wires to the sensor are bad or the instrument cluster is bad.

 

Since I've tried replacing the sensor twice already I'm going to eliminate that as the problem. I doubt the wires abruptly failed, possible but not very likely. And finally the most expensive one of the three seems to be the most likely candidate.

 

I will be back if/when I replaced the instrument cluster and let everybody know if it solved the problem.

Nice rig Enthusiast

Nice rig

Posted
Posted
OK! Guess I'll have to answer this myself.

 

According to Chevy's "official" manual there are only three things that can go wrong with water temperature indication....

 

The sensor (temp bulb) is bad, the wires to the sensor are bad or the instrument cluster is bad.

 

Since I've tried replacing the sensor twice already I'm going to eliminate that as the problem. I doubt the wires abruptly failed, possible but not very likely. And finally the most expensive one of the three seems to be the most likely candidate.

 

I will be back if/when I replaced the instrument cluster and let everybody know if it solved the problem.

 

 

 

Hey haze pa, chill out. :) Just by reading what you've posted I sense nothing but impatience and arrogance. The people on this site try to help...troubleshooting via the internet is a pain and requires a certain amount of patience. We are just people trying to help one another and if you expect an exact remedy then I suggest you go to a tech in person.

GM-Tech Senior Enthusiast

GM-Tech

Posted
Posted
OK! Guess I'll have to answer this myself.

 

According to Chevy's "official" manual there are only three things that can go wrong with water temperature indication....

 

The sensor (temp bulb) is bad, the wires to the sensor are bad or the instrument cluster is bad.

 

Well, duh. If you replace EVERYTHING, sensor, wiring, cluster, I'd guess you would probably fix it. I say probably because never put some weird occurance past an electrical problem in a vehicle.

KICK Enthusiast

KICK

Posted
Posted
OK! Guess I'll have to answer this myself.

 

According to Chevy's "official" manual there are only three things that can go wrong with water temperature indication....

 

The sensor (temp bulb) is bad, the wires to the sensor are bad or the instrument cluster is bad.

 

Well, duh. If you replace EVERYTHING, sensor, wiring, cluster, I'd guess you would probably fix it. I say probably because never put some weird occurance past an electrical problem in a vehicle.

 

 

 

 

 

since a temp gage is nothing but an ammeter with a scale labeled to reflect temp instead of amps, and the amount of current flowing thru the temp gage is an indicator of how hot the sesnor is, have you tried probing the signal wires to the gage with the gage disconnected while the engine is running, and seeing if the resistance is changing>

 

that'll tell you if the sesnor and wiring are OK and that the gage has seen better days.

haze_pa Enthusiast

haze_pa

Posted
  • Author
Posted

Hey! Nice rig, does your reply help? No! It doesn't. If you look you'll see that my original post was some time ago. I've been asking everybody I can think of for help on this and I finally got to the right person. I could have taken my truck to a shop and let them use the shotgun approach to troubleshooting or I could have taken it to a dealership and paid $75 just to have them take a look. I don't have the money to throw away these days.

 

I answered my own question because a friend brought in a GM tech manual that stated there are only three possible problems with the water temp indication and I listed them.

 

The "well duh!" reply wasn't particularly helpful either. Obviously if I replace everything it should fix the problem. My point being that I didn't know how many components were applicable to the water temp problem. I heard from somebody else there could be a voltage stabilizer involved. Turns out that's not the case according to the GM tech manual.

 

Now, if somebody else has this same problem they can read through and see what I went through and maybe save them some time and money.

 

If you can't offer anything useful, don't reply just to get your name in the string. If I offended you or slighted you in any way, tough! Get over yourself.

 

I appreciate any actual help I get and I thank the people who tried to help.

 

Rich

pm26 Senior Enthusiast

pm26

Posted
Posted

My experience with faulty temperature gauges on various vehicles, including my boat, were that the sensor was faulty most of the time, but sometimes it was a grounding issue. The sensor needs to be grounded through the engine block, right? Therefore, if you use certain sealants on the sensor, it may insulate it from the block. I believe they make conductive sealants that will eliminate this problem.

 

The gauge itself could be defective. A temperature sensor(or sender) is a variable resistor that will vary the voltage ouput to the gauge depending on temperature. The gauge needle fluctuates as the signal voltage varies. I have not seen a temperature gauge itself go bad on any vehicle I ever worked on.

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