Low temp gauge, no codes - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum



Welcome Enthusiast! If you already own a Chevy TrailBlazer or GMC Envoy or perhaps thinking of purchasing such a vehicle, then you have come to the best TrailBlazer and Envoy site on the net! Rainier, Bravada, Ascender, and 9-7x owners welcome too!

You are currently viewing our site as a guest which gives you limited access to view most discussions and access our other features. By joining our free community you will have access to search and post topics, communicate privately with other members, respond to polls, upload content, and access many other special features. Registration is fast, simple and absolutely free so please, join our community today!

If you have any problems with the registration process or your account login, please contact contact us.
Join Today!
Go Back   Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum > 2002 - 2009 TrailBlazer/Envoy Tech > 02-09 Vortec 4.2L I-6 Engine and Drivetrain > OEM Issues

OEM Issues Original Equipment Repairs and/or Problems

TrailVoy.com is the premier GMC Envoy Forum on the internet. Registered Users do not see the above ads.
Reply
 
Thread Tools
  #1  
Old 11-12-2010, 04:17 PM
coolcloo1019's Avatar
coolcloo1019 coolcloo1019 is offline
Senior Member
 
2002 Chevy TrailBlazer LTZ
Indigo Blue Metallic 4.2L I6 2WD
Join Date: Nov 2006
Location: Sevierville, TN
Posts: 790
Low temp gauge, no codes

Did some searching but couldn't find someone with the same problem I'm having. I replaced my thermostat in February because my gauge was reading low and I had CEL light on. Took care of that problem.

Within the past couple weeks I've noticed that my needle rarely gets past 2nd hash mark to the left of 210. Occasionally the needle will read 210 but goes right back down. This would lead me to believe my thermostat may be going out again but why am I not getting any codes if it's almost constantly 2 hashes below 210? Any ideas fellas?

Also, I replaced my battery about 2 months ago and within this past week if I am just idling, my battery gauge dips down to about 12 and then back to roughly 15-16 and keeps doing this over and over. Also makes my HID's flicker. If I idle the engine up to about 1k rpm, the lights smooth out and the gauge sticks around 15. Could this be an alternator issue?
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2  
Old 11-12-2010, 04:47 PM
Chickenhawk's Avatar
Chickenhawk Chickenhawk is offline
Senior Member
 
2004 Chevy TrailBlazer LT
Medium Red Metallic 4.2L I6 4X4
Join Date: Apr 2008
Location: Canada
Posts: 996
Plug in a scan gauge and take a look at the coolant temperature reading. If it is low and fluctuating, you need to replace the coolant temperature sensor.
Reply With Quote Quick reply to this message
  #3  
Old 11-12-2010, 06:29 PM
the roadie's Avatar
the roadie the roadie is offline
No longer with us
 
2004 GMC Envoy SLT "Roadiemobile"
Extreme Offroad Pewter 4.2L I6 4X4
Join Date: Apr 2005
Posts: 26,181
Could also be a bad replacement thermostat. I'd change both while I was in there.

Your other problem does sound like the alternator, or loose wiring, corroded connectors, or erratic idle. At idle, are you at a steady 600 RPM, or does it fluctuate? Have you ever cleaned the throttle body?
Reply With Quote Quick reply to this message
  #4  
Old 11-16-2010, 03:58 PM
coolcloo1019's Avatar
coolcloo1019 coolcloo1019 is offline
Senior Member
 
2002 Chevy TrailBlazer LTZ
Indigo Blue Metallic 4.2L I6 2WD
Join Date: Nov 2006
Location: Sevierville, TN
Posts: 790
Well I finally got a chance to get a scanner hooked up. The temperature reading on the scanner was fluctuating between 173-176*. I'd say it's my thermostat again. That's what I get for buying cheap I guess.
Reply With Quote Quick reply to this message
  #5  
Old 11-16-2010, 06:37 PM
Chickenhawk's Avatar
Chickenhawk Chickenhawk is offline
Senior Member
 
2004 Chevy TrailBlazer LT
Medium Red Metallic 4.2L I6 4X4
Join Date: Apr 2008
Location: Canada
Posts: 996
$20 it's your coolant temp sensor. Thermostats don't open and close that fast to cause fluctuations. When they go bad, they usually stick open and the temp stays steady, just too low.

The esteemed Roadie and I disagree on only one thing. (Well ... two, if you include who is better looking.)

He feels almost all the time it is the thermostat, and I feel that the coolant temp sensor fails almost as often as the thermostat.

My opinion: if the temp is low and steady, it is nearly always the thermostat. If the temp is low and fluctuates, it is nearly always the temp sensor.
Reply With Quote Quick reply to this message
  #6  
Old 11-16-2010, 09:00 PM
the roadie's Avatar
the roadie the roadie is offline
No longer with us
 
2004 GMC Envoy SLT "Roadiemobile"
Extreme Offroad Pewter 4.2L I6 4X4
Join Date: Apr 2005
Posts: 26,181
Quote:
Originally Posted by Chickenhawk View Post
He feels almost all the time it is the thermostat, and I feel that the coolant temp sensor fails almost as often as the thermostat.
If the temp gauge needle goes to an impossible angle, like straight down, it could be the instrument panel stepper motor. But that's even more rare.
Reply With Quote Quick reply to this message
  #7  
Old 11-16-2010, 09:33 PM
SCmike SCmike is offline
Junior Member
 
2005 GMC Envoy SLT
Medium Red Metallic 4.2L I6 AWD
Join Date: Oct 2010
Location: Sumter, SC
Posts: 4
CEL driving me crazy!!!

I recently replaced the coolant temp sensor due to the CEL being on. I ran a scan and got (2) error codes saying the sensor was the issue. After replacing the sensor, I drove the Envoy about 2 days with no trouble. Then after the car had been sitting for about 2 hours, I crank it up and the CEL comes on immediately. I rescan and get the same thing; coolant temp sensor x2. What's up with this? Prior to changing the coolant sensor, I just replaced the entire computer system and had it flashed by the dealer.
Reply With Quote Quick reply to this message
  #8  
Old 11-17-2010, 10:15 AM
coolcloo1019's Avatar
coolcloo1019 coolcloo1019 is offline
Senior Member
 
2002 Chevy TrailBlazer LTZ
Indigo Blue Metallic 4.2L I6 2WD
Join Date: Nov 2006
Location: Sevierville, TN
Posts: 790
But if it was the thermostat again, shouldn't I be getting a CEL?

I guess the easiest thing would be to just replace both the thermostat and the sensor and then there will be no questions...
Reply With Quote Quick reply to this message
  #9  
Old 11-17-2010, 10:20 AM
Super 88's Avatar
Super 88 Super 88 is offline
TrailVoy Alumni
 
2005 Chevy TrailBlazer LS EXT
Midnight Blue Metallic 4.2L I6 2WD
Join Date: Oct 2006
Location: North San Diego
Posts: 2,667
Quote:
Originally Posted by SCmike View Post
I recently replaced the coolant temp sensor due to the CEL being on. I ran a scan and got (2) error codes saying the sensor was the issue. After replacing the sensor, I drove the Envoy about 2 days with no trouble. Then after the car had been sitting for about 2 hours, I crank it up and the CEL comes on immediately. I rescan and get the same thing; coolant temp sensor x2. What's up with this? Prior to changing the coolant sensor, I just replaced the entire computer system and had it flashed by the dealer.
It would be helpful if you told us what code number you are getting.
Reply With Quote Quick reply to this message
  #10  
Old 11-17-2010, 06:50 PM
Chickenhawk's Avatar
Chickenhawk Chickenhawk is offline
Senior Member
 
2004 Chevy TrailBlazer LT
Medium Red Metallic 4.2L I6 4X4
Join Date: Apr 2008
Location: Canada
Posts: 996
Quote:
Originally Posted by coolcloo1019 View Post
But if it was the thermostat again, shouldn't I be getting a CEL?

I guess the easiest thing would be to just replace both the thermostat and the sensor and then there will be no questions...
The CEL illuminates after a certain period of low temps, but when it illuminates, it tends to be REALLY bad. A slight tick to the left doesn't show anything.

The problem is that the dash gauge is not linear. That slight tick to the left is actually a big drop in temps, and can certainly adversely affect your mileage.

As to changing both, we usually recommend folks do this just because it is a pain to get at both so once the alternator is out, you might as well. On the other hand, the sensor can be slapped in with little to no coolant loss, and the thermostat requires draining a fair amount of coolant, so if the indications are that it is the sensor and if you already changed the thermostat with a good brand-name one and if one feels lucky, it might be worth it to try the sensor first.

I did, and this is how I know the indications (fluctuating temps, especially on the highway) that it may be the sensor and not the thermostat this time.

Good luck and let us know how it works for you.



And ... by the way, I need to add that the Roadie has a million times more experience than me with these vehicles, but I still am better looking.

After all, I may be the most boring person on the face of the earth but I still get compared regularly to the Dos Equis guy ... and I once doubled for Dennis Farina in a movie!

Take THAT Roadie!

Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum forums, you must first register.

Please enter your desired user name, your email address and other required details in the form below.
(Only letters, numbers, dashes and underscores are permitted for user names)
The user name that you choose is permanent and can never be changed.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


» Sponsors

Advertising Info

All times are GMT -4. The time now is 02:08 AM.


Chevy TrailBlazer and GMC Envoy Enthusiasts - Copyright 2004 - 2009 All Rights Reserved.
All trademarks referenced herein are property of their respective owners.
RSS Feed