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I have a 2006 H3 that I just had a diagnostic done on, they told me that I had a computer module out, which I had them replace, and that I need a new thermostat, I bought the thermostat from the chevy dealer and now need some advice on locating it and changing it, any help would be greatly appericiated.
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You need to drain the coolant, jack it up enough to get the front driver's side wheel off, remove the wheel well liner and now you can access the thermostat. Follow the radiator inlet hose to the engine block. Remove the hose clamp and 2 thermostat housing bolts. Replace thermostat, put everything back together and refill coolant.
I haven't done it yet, but i've looked into the install since i think mine needs replacement as well. The price of the thermostat and coolant alone is probably $100, i didn't even bother calling a dealer. Hope it works out for ya
Regarding the P0128 code: thermostat or temp sensor?
shouldn't both be changed? at least that was suggested somewhere since you can't tell which one is actually faulty and exactly where is the temp sensor located? Your diagram of the thermostat location was most helpful. I have a 06 H3 70k, dash gage between 1/4 to 1/2 when warmed up, plenty of cabin heat, had CEL cleared now throwing the P0128 code again.
If you search that code there is another thread going that is tied back to this one.
In my case, the first time I threw a PO128, I found the cracked radiator. I replaced the radiator and thought I was good. About a month later I threw the code again. The main call out in the maintance manual is the thermostat. I had it replaced and have been good ever since. Since new, I have replace the heater core, radiator, all hoses and now the thermostat. I'm not sure if any of them are a result of the early heater core failure (6 month old at the time) or not.
I have not had to replace the sensor or gauge... yet. After the thermostat was replaced my gauge does read a quarter higher when warmed up (above half way now).
Red 06, hood stripe, red & black leather interior, tow package, Monsoon radio, iPod attachment, body lift, Tbar crank, Bilstein shocks, extended bump stops, air horn, flares w/guards, 35's, GM exhaust, H3 tips, intake, filter, tune, UCP, diff slider, spring delete, ported throttle body, ladder, Thor bumper, winch, dual batteries, Tmax controller, KC lights, red grille, BA shock slider, stealth rack, rock sliders, Hi-Lift jack, drill/slot rotors w/ceramic pads, braided lines, shock/spring sliders
On the HummerXForum I did find a diagram identical to the one Doc Olds presented on this thread which additionally included the location of the Temp Sensor (CTS) and was labeled as #313. Located opposite side of the thermostat housing (on the passenger/exhaust manifold side) appears near cylinder heads 2/3.
I've read where one might as well change this $15 sensor also along with the thermostat since your draining and replacing the coolant anyway. If this sensor eventually corrodes it makes sense to change it now @ 70k. From what I've read the dash gage has no bearing from vehicle to vehicle. Most common between 1/4 to 3/4 after the engine is warmed up, I'll keep an eye on it and eventually report once I have the work done. I'd welcome any further comments.