no overdrive
12-03-2018, 10:11 PM
#1
Thread Starter
Join Date: 12-03-2018
Location: kansas city
Posts: 7
no overdrive
New to this site and hope for some help solving my problem. I noticed this morning while driving my 2010 HHR with a 2.2 to work that I no longer had overdrive, all else seemed good, just showing 3000 rpms while going 60 mph, also noticed the coolant temp on my DIC display had the temp readings going all over the board jumping temps from 194 all the way down to 181, and moving up and down constantly but staying below 190 most of the time. Heater working ok, and them I got a check engine light with a P0700 code. My question is, can a faulty temp sensor cause my overdrive not to kick in? All other shifts are good, and has no fluid leaking anywhere.
12-03-2018, 10:52 PM
#3
Moderator
Join Date: 05-01-2014
Location: California
Posts: 7,808
Hi black2010, 
to the forums!!
The p0700 is a generic transmission code, telling you that there is a problem with the transmission. You will need a better tool to get the actual codes. Often the codes are followed by a suffix. Post the codes here, make sure you include any suffix.
to the forums!!The p0700 is a generic transmission code, telling you that there is a problem with the transmission. You will need a better tool to get the actual codes. Often the codes are followed by a suffix. Post the codes here, make sure you include any suffix.
12-04-2018, 05:05 AM
#5
Thread Starter
Join Date: 12-03-2018
Location: kansas city
Posts: 7
Thanks for the responses, I read that if the TCM doesn't get a correct temp signal, that is may not make the overdrive shift. By the way the temp readings are fluctuating like crazy, that the TCM may not be getting a correct reading. The temp readout used to always be very consistent right on or about 195 once operating temp was reached. Will do more investigating today.
12-04-2018, 08:10 AM
#7
Technical Moderator
Join Date: 01-23-2009
Location: Fredericksburg, Virginia
Posts: 24,692
181-190 is better than 195 always, both are okay. So I don't think that is the trans problem. Would not hurt to change t-stat, sensor and DexCool (it has a shelf life of 5 years).
12-04-2018, 10:47 PM
#8
Thread Starter
Join Date: 12-03-2018
Location: kansas city
Posts: 7
Well I replaced the coolant temp sensor and t-stat with correct GM parts, and still have the same issues,so that did not help with the problem. Trans still will not shift to overdrive, and is pulling the p0700 code, with no other codes present. The one thing I do not understand, is my DIC temp display still shows the temps fluctuating constantly up and down between 181 up to 194, does not hold a constant temp display. It used to hold a pretty constant 194 reading before. I did remove and reseat the tcm connector, but no changes in the overdrive shift issue. I will continue to look and check out different things related to the trans.
12-05-2018, 08:09 AM
#9
Technical Moderator
Join Date: 01-23-2009
Location: Fredericksburg, Virginia
Posts: 24,692
Do you mean the display flashes back and forth 181 then 184?
It is normal for the temp to vary from 181-219. Not flash. You might be low on DexCool; check under the pressure cap.
Lately, we have been hearing about oil and water migrating up the wires to the computers.
It is normal for the temp to vary from 181-219. Not flash. You might be low on DexCool; check under the pressure cap.
Lately, we have been hearing about oil and water migrating up the wires to the computers.
12-05-2018, 12:18 PM
#10
Thread Starter
Join Date: 12-03-2018
Location: kansas city
Posts: 7
The temp display will just flip up and down to different temp readings maybe once every couple of seconds, this started the same time I lost overdrive, my temp gauge itself looks to be holding steady where it always has, but the digital coolant readout on the information center is the area it is fluctuating. Makes no sense right now to me why it is doing it. My coolant levels were correct before I changed the temp sensor and t-stat and are correct now, so that isn't the issue. The check engine light with the p0700 did not display for the first time until I had driven it about 20 miles with no overdrive.