Temp gauge goofy

[Lee4212]

My 2005 3.4 v/6 impala has just started having the temperature gauge acting goofy.
It can start reading at mid point (say 200 degrees) when COLD. I did have the fluid changed, flushed and a new thermostat installed since it was time. It wasn't zero-ing out when car was off, it sat about in the middle. They ran a sweep of the gauges and found that gauge was acting erratic.
It was reading say 240 when cold before they found the issue.
After the sweep it reads fairly normal and sit's at zero when car is off BUT it's just a matter of time before it goes nuts again so....a new cluster unit installed is $600.00 ! Wow.
I wonder if I could just splice new wires from another gauge I get and place under the dash?
Should I just get the cluster installed and be done with it? Are used clusters worth it?
Others guys say to not worry about where the gauge reads at since it's getting goofy but what if something happened and it did really run too hot !
Could I change the cluster myself or will it need to be programmed?
Thoughts/input??
Engine wise it has been flawless and super smooth running.
OH. Dealer gave me the wrong bulbs for license plate, it was way to big so auto parts store here I come! I had to go the a dealer since my car mechanic was swamped with work..i got stuck with a BIG bill but, it is what it is.

 

[chemman]

I would first check to make sure the plug to the coolant temperature sending unit is plugged in all the way. Next, I would make sure the ground side of the circuit is good (ohm it out with a multimeter). If all checks out, then I would change out the coolant temperature sending unit. I had one go bad in my 1992 Olds 88 and it acted just like you described. A new coolant temp sensor sells for about $20.00.

Remember, the gauge displays the information that is sent to it from the coolant temperature sensor and the ECM.

Good luck.

 

[Rick in PA]

Everything goes through the computer these days. I remember thinking how steady the temperature gauge on my car read. It would rise from cold to mid-range and be pegged there as the car ran. Later, I found out that the computer controls the temperature gauge and it filters out normal engine temperature variations, so as not to worry the user.

Perhaps a scan tool could be used to determine if the computer is getting valid temperature information from the temperature sender (sounds like the dealer did that).

I suspect that to install a separate temperature gauge would require a fully separate sender + gauge. The original would have to be left in place as the computer will need its temperature data to operate correctly (or you'll get the dreaded "check engine light").

 

[Garak]

Originally Posted By: Rick in PA
Everything goes through the computer these days. I remember thinking how steady the temperature gauge on my car read. It would rise from cold to mid-range and be pegged there as the car ran. Later, I found out that the computer controls the temperature gauge and it filters out normal engine temperature variations, so as not to worry the user.

Somewhat off topic, GM was one of the last ones to do this, and it was nice to be able to actually see and understand what's going on. My god daughter's older Monte is a proper gauge, and it "worries the user" as you indicate.

But she is beginning to understand the normal behaviour.

 

[Lee4212]

Thought about just changing the sending unit myself just to be sure. I see it so I can't be that hard...right? They did do a sweep of the cluster gauges and at the moment it reads zero when cold but...one never knows.

 

[Carbon12]

I had a 2004 cavalier that did the same thing. I ended up putting a couple thermostats in it before it became obvious that the gauge itself was failing. The rest of the gauges starting failing eventually. When I traded the thing in the tach was all that worked. Currently experiencing difficulties with gauges on a 2003 GMC Sierra. The early to mid 2000s GMs are prone to these issues.

Also being that it is a 3.4, you want to keep a close eye on the coolant level since the intake manifold gasket fails and allow coolant into the crankcase. Maybe get a UOA once in a while to keep an eye on Potassium (K) which is an indicator of coolant in the oil

 

[daman]

ebay has clusters everyday for cheap.. plug and play.

 

[eljefino]

+3 on the coolant temp sensor. Can you get temp on the driver information display? That would use the same data. Or scan tool. Does your rad fan run with the AC off and a cold car? That would indicate a fail safe is in effect. Check Engine light on?

 

[Johnny2Bad]

Most modern cars come with a coolant temperature gauge that is actually an idiot light. It operates just as one would, go / no go rather than linear temperature readings.

Consumers like gauges so they give them gauges. Sort of. Has been common practice since the mid-1990's when ODBII was introduced (1996).

 

[JimPghPA]

When the sensor for the fuel level went on our 2001 Impala I picked one up for about 1/10 the cost of an original equipment one from RockAuto. Check e-bay and RockAuto to see if you can find an after market instrument cluster for a much lower price then from a dealer.

 

[tnt31]

+4 on the Coolant Temp Sensor. Had similar experience with wild temp swings indicated on the Temp Gauge on a GM 3.9L V6. Replacing the CTS resolved it. I think I paid less then $20 with shipping for a Delphi CTS from Rock Auto so fairly inexpensive to try.

 

[Anduril]

I was going to second/third/etc. the sensor. Much cheaper than the gauge cluster, and IMO more likely to solve your problem. You can verify with a scan tool - if the temp reading given to you by the computer is all over the place, it's the sensor. If it does what you'd expect while the gauge doesn't cooperate, then replace the cluster.

 

[Silverado12]

You have a bad cluster. It's a common problem on these cars and what kind of gives it away is the gauge points in a weird direction when cold. I had a fuel gauge on a similar Impala do the same thing. Replacing the cluste is a DIY job, but the dash has to come off. I can explain it if you want, but basically there are a few screws and the rest pops off. Some of the screws are hidden, so if you don't get them all you'll break your panel. IIRC there are 2 screws behind each end (fuse) panel, two on the cluster visor and one near the headlight switch that you see once you pop off the bottom panel.