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Gary, Buick Technician
Category: Buick
Satisfied Customers: 15562
Experience:  15 years master GM tech and mater ASE tech
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2002 Buick Century: temp gauge into RED, TEMP...lit..hills; engine

Customer Question

2002 Buick Century: temp gauge into RED, TEMP. icon lit; car has no power(no advance, will barely make the hills; engine not really that hot.
Does the computer take its cues from the gauge/sender info.?
Submitted: 5 years ago.
Category: Buick
Expert:  Gary replied 5 years ago.
how quickly will it get into the red and over heat?
Customer: replied 5 years ago.
It goes immediately into the red, even after sitting for a while.
Expert:  Gary replied 5 years ago.
so starting this cold in the morning as soon as you start it up it spikes into the red?
Customer: replied 5 years ago.

I left the car at a friend's place 30 miles away yesterday and I have not been back yet; please cancel my inquiry for now. I am also in the process of signing up for the monthly

plan. I will return to this space after I check out the car tomorrow. Must attend New Year's dinner to-day at Mother-in-Law's.

Expert:  Gary replied 5 years ago.
just reply back threw this post when you can and i will answer your reply rush
Customer: replied 5 years ago.

Hello, gmwrench; I'm back...

I went to the car the next day; the gauge was down to cold, so I started the car.

It ran fine, so I headed for home- 50 km./ 30 mi. away. After 4 or 5 mi. (when it warmed up), the gauge trotted on up to HOT and she lost her get-up-and-go, as before(engine protection mode).

I pulled over, opened the hood and disconnected the wires from the Temp.

sending unit. I then tested the harness as per my Haynes shop manual– run a jumper from the green wire terminal in the plug to ground. Nothing. The dash gauge didn't

move. So then I thought: I'll just leave the plug off and drive 'er home like that.

Wrong. Now it wouldn't start at all. Finally, I put a jumper between the green wire and

the orange w/black wire in the plug. It seemed to work: I drove home, the car ran well,

the Rad. cooling fans operated; I drove some to-day, also. What does this mean?


Expert:  Gary replied 5 years ago.
which switch did you jump?and where is it located?
Customer: replied 5 years ago.
I jumpered the plug that I disconnected from the Temp. sending unit.
Expert:  Gary replied 5 years ago.
a 2 wire connector you jumped? this one here?graphic
Customer: replied 5 years ago.
Yes, that looks like it, but mine has 3 wires– orange w/ black, light green and dark green.
I jumpered the dark green & the orange w/black stripe.
Expert:  Gary replied 5 years ago.
so if you hook that back up and idle the engine will the cooling fan come on?
Customer: replied 5 years ago.
Expert:  Gary replied 5 years ago.
ok.we either have a sensor problem or the possibility of a bad head gasket allowing compression to enter the cooling system and cavatating the coolant and causing this car to over heat.try the sensor first if that doesn't do it more than likely the head gaskets are causing this problem
Customer: replied 5 years ago.
As I mentioned way earlier, the car is not over-heating; just the gauge says it is.
As I mentioned earlier, the gauge failed the jumper-to-ground test.
Expert:  Gary replied 5 years ago.

im sorry i missed that post

do you have any access to a scan tool so we can perform a needle gage sweep to see if we have a cluster problem or wiring or computer problem?with that sensor plugged in we need to know if the PCM is getting the correct tempature reading.the computer gets the temp reading then sends that to the IPC gage cluster.

Customer: replied 5 years ago.

I have a CAN OBD2 tool, but I'm not very experienced with it. Tomorrow I'll hook it up,

reconnect the plug to the Temp. sending unit and give it a try.

I have the manual for theOBD2 but what should I do, in what order? Start the car?

Take readings first? Warm the engine up...???

Expert:  Gary replied 5 years ago.
as you run the car see if the PCM coolant temp is reading the same as the tempature gage reading on the gage cluster
Customer: replied 5 years ago.

I'm sorry I haven't gotten back to you; I've been busy day and night for the past week:

gas tank on my Mazda pickup, wheel bearing/hub on my '97 Buick and thus brake service, Wife in hospital, work – the list goes on.

I am on the Just Answer monthly pay plan, so I will get back to this issue soon, maybe this week-end.


Expert:  Gary replied 5 years ago.
no problem

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