Temp gauge woes Qs

[Phoenix]

My temps gauge is acting *** lately , it gets to the top (near the red line) really quickly , it goes up and down sometimes rather quickly (jerks). But the hottest temp im recording with the laser temp gun its 200F on the neck of the termostat (it new btw). The fan works fine.

So im guessing the temp sender is screwed? or the cluster is acting up? Anyone ever got this?

 

[Mr Anonymous]

A failed gauge sender is most common and is less than $10 US.

I have seen the gauge unit in the cluster fail too, but not nearly as common as the sender.

 

[shoon]

sender should read:
hot - 10 ohms
cold - 74 ohms

could check the sender with a ohmmeter first to be sure.

 

[Phoenix]

Alright , heres an update

Temp sender replaced with a good old one , worked fine for 10 miles , when I came back from that trip , it acted again.

I will look at this shoon , thank you

By any means , just for the heck of it , what kind of temperature im looking at if the temp was REALLY in the red , 250-300 deg?

Also , sometimes when I shut off the car (well the gas and temp needles goes some random places) , well sometimes its way passed the red hot point where it should stop....does it only once in awhile.

One last thing I saw , when I turn on the blinker to turn , the needle fluctuates (very little) with the blinking. Im maybe looking at an electrical issue.

Anyway thanks for the help , whatever it may be.

 

[K-Dawg]

I was going to suggest that you have some air in the system, but it sounds like you've got an electrical problem. Do you have access to a different gauge cluster?

 

[shoon]

This image is specific to the SHO

 

[Phoenix]

Cant swap the dash , sold mine spare a couple months ago , SHOON I printed that , and looking foward to crush that bug....

 

[shoon]

Cant swap the dash , sold mine spare a couple months ago , SHOON I printed that , and looking foward to crush that bug....

looking through some wiring diagrams, check your grounds at the left front fender apron. maybe pull the bolt off, polish and grease the connection.

 

[Phoenix]

looking through some wiring diagrams, check your grounds at the left front fender apron. maybe pull the bolt off, polish and grease the connection.

Allrighty , I will do this , this week. I will keep you guys updated.

 

[shoon]

Allrighty , I will do this , this week. I will keep you guys updated.

Update?

 

[Phoenix]

Yup , I changed the cluster. Now the temp still is high but it fluctuates alot less with this dash. Im gonna double check if the fan starts all the time , tomorrow I will wire the fan staight to the fuse panel and see if the temp stabilizes.

Like I said , I was sure is was a sending unit issue but Im starting to think it may be the real temp....even though I never got more then 200 deg with the temp gun.....

 

[shoon]

hmm...

Do you have an analog ohmmeter?
I'm thinking, get yourself some test leads and an analog ohmmeter, Zero the ohmmeter and connect it to the ECT sending unit.

Start the car and check to see if the needle bounces all over the place as the coolant heats up. If all looks good, pull the cluster out, and use the ohmmeter on the connector that plugs into the back of the instrument cluster, start the car and check readings again.


Will help you rule out ECT sender & the wiring from the ECT sender to the instrument cluster itself.


If ECT resistance bounces all over the place (with meter directly connected to ECT) then you know either the ECT is bad or you got something weird going on with your coolant temps.


Edit:
Let me know if you need pinouts for the Instrument Cluster connector and also, the cooling fan will turn on if the car heats up to a certain temperature &/or the AC is turned on; BUT it turns off if you are driving more than 30 mph

 

[SHOZ123]

ECT is for the fans but the gage comes off the CTS which is a simple one wire grounded device. To check the gage ground the temp sender wire, it should read full hot and apply 12V it should read full cold.

Sounds like either the wire is shorting out or you have air in the system and quite a bit of it too.

The Hot part of the gage outside the NORMAL range is ~250F.

 

[Phoenix]

Alright , even with the fan on 100% of the time , it does the same thing , so its most likely the sender and not the real temp of the engine.

If its gets high (1/8" before the redline) , and I use the flasher , it goes down a bit - and after it goes up again slowly. When its high , I shut down the car turn back on the key and its temp is in the middle where it should be.

When I start it cold , everything is fine , it goes up normally but it doesnt stop in the middle , goes way up.

Note that I only changed the fuel and temp gauges , not the whole cluster (cause I found a sable cluster locally) . Maybe its the damn cluster.

I double checked the G103 ground and removed any rust....

I installed 2 senders , same issue.

Its either the cluster itself , sending wire or the ground. I will directly ground it and see what happens.

 

[Phoenix]

Solved.


It was a bad ground, the one the sender uses just by screwing it in the block , I installed a temporary ground fron it to the G103 ground and , no more of that rising temp.


Thanks for all your help guys.