PontiacBonnevilleClub.com

If it's pinned, it's electrical meaning an open in the circuit somewhere as it's reading "infinite" resistance. If it's electrical, it's usually one of two things. The ECT sensor or the stepper motor in the cluster. GM calls for IPC replacement, but sme here will just replace parts internally.

Many in this section (as well as Bonneville's in general), have had similar issues. It could be the wiring too, but usually it's one of the others.

Exactly the problem my wife had with my 2005 GXP, while In FL a number of years ago. Eventually, the temp gauge kept failing regularly, and then the fuel gauge started fluctuating. Last year had the entire cluster replaced, unfortunately outside the warranty. All has been well since then.

I believe the DIC throws a message once it starts getting past 260 on the SSEi's. Not sure why GXP would be any different. Can you check coolant temp on the DIC?

You can get a scantool on the car to confirm the temperature reading matches that of the gauge, but my hunch is that the cluster stepper motors have failed. This is a common failure for many mid 2000's GM vehicles - not just the Bonneville. There are many websites who will replace all bulbs and motors in your cluster for anywhere from $100 to $120, and have a quick turnaround. You just have to ship it to them (you can still drive your car without a cluster if you need to). If you're daring enough and are good with soldering/electronics, X25.168 stepper motors can be found on eBay.

The DIC should also warn you if the car is in overheat territory, though the exact temperature threshold escapes me

Is there a tutorial on how to remove the cluster? I'd like to take mine out and ship it off to have the motors replaced.

There's a reply in your thread posted back in December: http://www.pontiacbonnevilleclub.com/fo ... 36714.html

Thanks!

So it can't get it up?

Repair, don't replace. That is 100% rebuildable.