I'm going nuts trying to find some info online and having no luck. Shoot me a PM if you know the answer to this... 2005 GMC Sierra 4.3. Check engine light started coming on, got a code that said "Coolant Temperature Below Normal." I figured I'd just replace the thermostat and be done with it...Is the thermostat in that vehicle under the spot and thing that looks like a thermostat housing for a SBC, right at the front of the intake, with two bolts on it? Also, since the gauge is reading the way it has always read, I'm wondering if it's a faulty temp sensor to the ecu or if the extra bumpy roads where it is right now are causing the plug to wiggle and make a bad connection. Where would I find that coolant temp sensor? Thanks. Sorry for clogging board with this late model crap...the GM board was absoultely useless all week. Thanks.
Not a GM tech but my experience with computer cars is that sometimes they just get a bad code. I think that the computers may not be American made (although your cable sets for that year are American made by Arrow Electronics). Anyway sometimes something just screws up and the computer gets confused. Before you start changing parts erase the code (I usually just unhook the battery for 30 seconds to a minute) then drive it again and see if you get the code again. Now the real wize kids can chime in and you'll get a much better answer. Oh your water temp sendor can be in the head or near the T stat houseing or in the radiator tank. I've seen them in all those places on GM vehicles.
The thermostat housing connects the upper radiator hose to the intake manifold, like a SBC. The coolant temp sensor looks like it is next to the thermostat housing on the front of the intake manifold also (between the thermostat housing and the heater hose). Hope this helps.
Thanks guys...this is INFINITELY better than anything I've found before. My friend (Oldcarpilot) is borrowing it while in town, and he keep saying that the light will go on for awhile, then magically go off, so I'm leaning toward it being a confused computer, for whatever reason. I used to have a Quad 4, and I went to seal up a leaky thermostat housing...at least that is what I would have bet $500 that the name of the part was. I took it off and found no thermostat underneath...it was simply a "Water Outlet." The thermostat was hidden in the back where it was nearly impossible to get to, thankfully (at that time) I didn't need to...I just wanted to make sure I don't have a repeat when I start taking things apart on this one. Thanks.
Get an ACDelco or GM Thermostat... ACD# 131-151 GM# 12597583 http://webcaps.ecomm.gm.com/internet/PartImage.jsp?mfgname=ACDELCO&prodlinecd=13&acpartnbr=131-151 My guess is the coolant temp sensor... ACD# 213-928 GM# 15326386 http://webcaps.ecomm.gm.com/internet/PartImage.jsp?mfgname=ACDELCO&prodlinecd=21&acpartnbr=213-928 The electrical connector for that sensor is... ACD# PT1798 GM# 88987993 http://webcaps.ecomm.gm.com/internet/PartImage.jsp?mfgname=&prodlinecd=&acpartnbr=pt1798 Don't buy aftermarket junk... http://webcaps.ecomm.gm.com/internet/Vehicle.jsp
Wow!!! Im glad to see people being so helpful, and not tearin up the thread for talkin about a OT car...
I work at a GM dealership in parts and just talked to one of the techs he said check the coolant level if it's ok put a thermostat in it and wa la.
took a "poll" in the shop . majority rules , we all agree its the coolant temp sensor (2 wire connector) should fix the concern .
Two cents from a service manager in a g.m. dealer..thermostat.See it quite often,its sticking,causing the engine to take too long to warm up at times. (emissions)
Thanks to all. I'll try to snag the parts listed, (and return the aftermarket junk I already bought!) starting with the simpler fixes first. 44,000 miles on the odometer...I guess the age is more of concern, though. Thanks.
The temp sensor is about half way back on the left cylinder head on a 4.3. If the thermostat is stuck open this would also cause the code to be set. The computer looks for 185 degrees on the coolant and 600 degrees on the O2 sensor after the engine is warmed up. Code may be cleared from computer by disconnecting the battery cable for longer than three minutes. Hope this helps, Buffalotrux Keepin 'em inline since '53
Well I thought about it but its a chebby and I'm havin' enough fun on the oil thread. Ya know are you sure you have enough zddp in it?
What is the code with the light? A p0128 is a death sentence for a thermostat. Are there any other codes? are you super low on coolant. Those plastic maniflods on 3.8 L and 4.3L paid for my college. DO NOT get a shitty aftermarket thermostat either. They probably wont fix the P0128. On second thought, take it to a GM dealer if you dont know where the thermostat is, if you start craking open that cooling system and get air trapped in that thing, your motor is toast and the temp gauge may not tell you. Ive seen it alot on s-10 blazers and that is a $5,000 bill after I put a motor in one of those. Also, You CAN NOT, I repeat CAN NOT clear codes by disconnecting the battery after a hard code sets. It is stord in the history of the ecu and needs to be cleard wiht a scan tool/code clearing device. The light will go off after 50 cycles, but the code will still be there which may cause more of a headache later on.
If you had a scanner that gives you data stream, you could hook up and look at CTS temp vs. the gauge reading. If CTS is obviously lower than the gauge, then you have a bad CTS. I doubt the connector is wiggling loose. If CTS and Gauge appear to agree, probably a sticking T-stat. Or you could just replace them both and flush the coolant at the same time and be done with the problem.
#1. You can't clear that code by disconnecting the battery #2. That code relates directly to coolant temp being too cold or taking too long to come up to temp #3. Thermostats are frequently the cause of this problem, replace it. #4 If the temp sensor went "open" or "shorted" you would get a different code #5. Alot of guys on this board are sharper than those on the GM forums...I know, alot of them worked for me in my previous career.
You guys are kicking ass here. Thanks from me too. (I'm borrowing the truck from him) It is a P0128 code. We'll replace the thermostat stat!
Funny.. I've cleared plenty of codes by disconnecting the battery. It takes a lot longer than 30 seconds.. but it can be done! I am a GM technician (of the transmission variety mostly but I dabble in everything) I've had plenty of ECU codes clear in the time it takes me to either R&R or overhaul a transmission. to the OP, Yes.. We've replaced many a thermostat for that reason. If the engine takes too long to get up to the predetermined temperature, it will set the code. Someone else I believe already posted that if the ECT sensor was malfunctioning you'd have a different code either instead of, or in addition to your current code. Blame the EPA. Good luck with your repairs!
I have had this happen twice on my 06 GMC. Only 81,000 miles, don't know why GM can't correct this issue since i've read this is a common problem with the 4.3.
GM tech for 25 years. Replace the thermostat. OBDII codes will not clear by disconnecting the battery! ( the early systems will ) The light will go out after 3 drive cycles if a fault is not detected in the coded system. History codes clear after 100 cycles without a fault detected.
yup me too but on my 04. first time dealer replaced the thermostat under warranty, second time i did it replacing all the hoses at the same time. in this hot AZ climate i felt better with new hoses after 4 or so tears. i'm at around 75000 miles now. later jim
p0128 is common on all GM's, we see a lot of them. atleast the 4.3 is easily gotten to, try a 3.4 in a 'U' van after the people have driven what seems like a thousand miles to get to the dealership, and want to wait for the repair, lol.
If you use dexcool the red .Drain it out and replace with the normal color antifreeze .There has been alot of said and noted problems with this antifreeze .This is nothing to do with your thread but just some friendly advise ....Look it up on your computer if you like.....
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