Tranny slip? Electrical or mechanical? Please help asap

gmc
terrain

#1

Please help guys, my wife has a 2011 GMC Terrain SUV and on my way home, the accelerator became intermittently unresponsive, like I was revving it in park but still “caught” to get me to Auto Zone. The scan revealed PO700 PO716 PO717. One is a “Transmission Control Module Requested MIL Illumination”, the other an "Input Speed Sensor Performance, and “Input Speed Sensor No Signal”.
The Tranny Module is a $325 part with $300 core charge, but I don’t know if it’s dead, the speed sensor $40.
I just had a different module replaced this week which fixed her car for a few days (it was dying at idle) $180 with labor.
Any info? We really cant handle major Tranny work now as my wife will have major surgery in 2 weeks. Please advise me guys. Thanks so much


#2

I will also say I can smell gas very clearly on her oil dipstick which I have heard means fuel injector probs, and I found something that plugs into the intake manifold had popped off (I replaced it), it looks like the boot of a spark plug wire, just a bit smaller. The mechanic obviously didn’t put that back on securely.


#3

Here is the definition for the P0716 code:
CVT Input Shaft (Drive Pulley) Speed Sensor “A” Circuit Range/Performance.

The other code relates to that sensor also. Check the connection to that sensor and also the power for it along with the wiring to that sensor from the ECU. Hopefully it’s just a bad connection to the sensor. If the wiring checks out then I would focus on replacing that sensor.


#4

Please forgive my ignorance, is the “pulley” my serpentine belt? I am poor at modern cars, in other words, is it “slipping” because a belt is slipping or do you only suspect the sensor/wiring?


#5

The P0717 is a failed turbine speed sensor. That will cause a P0716 AND a P0700 code. Replacing the turbine speed sensor will possibly clear up the other 2. It is NOT likely the module. Replace the $40 sensor and check again.

As for gas in the oil, that’s another problem to address ASAP.

If you are in over your head with these repairs, it might be more cost effective to bring in a pro before serious damage is done.


#6

No, it is not. It is part of the transmission. Not to be rude, but if you are asking that, It is time for a pro.


#7

Also if I may ask, the Auto Zone scan for PO 700 indicates its the TCM "Tranny control module, a friggin’ $325 part with a $300 core charge, the speed sensor is barely $40, which are you leaning towards? I understand I’m asking for your advice “blind” but you clearly know what you’re doing…and thanks and God Bless you for helping us. (I dont mean to sound cheesy, but my wife is having major surgery that will cost us a small fortune in 2 weeks, I cant just keep dropping new sensors in to guess.


#8

It’s not rude, I just don’t know much about modern cars. I ask for advice here so I don’t show up and have the mechanics just keep replacing sensors without need. The mechanic put in a new sensor 4 days ago, clearly that wasn’t the problem…


#9

If you walk into a mechanic “blind” it’s just as bad as a woman going in for an oil change and having her told she needs an intake manifold, understand? I know the repair is likely beyond me, but it will help if you guys tell me what I should have done


#10

Thanks Mustang, that’s what I was hoping for, we will begin with the speed sensor.
Any idea what the “boot” (looks like a sparkplug boot but smaller) is that was popped off the post? It plugged into the side of the intake manifold cover (see, I know some stuff (-;/. My mechanic obviously didn’t put this back on properly, it was swinging free before I replaced it.


#11

I will do as you suggest on the gas smell on the oil dipstick. I read that it is often a fuel injector fouling that causes this.


#12

If you think you need to act like that, don’t use that mechanic. Find a trustworthy one. They are out there. You can find some on the CarTalk Mechanics files.

Lots of people think they need to walk in knowing what might be wrong or they will get ripped off. If you walk in and tell the mechanic what to change, he will change that and you might not get the problem fixed. Describe what the car is doing, pay him for his diagnostic time and let him (or her) fix the car.

And ignore what AutoZone or O’Reilly’s tell you except the P0700 or whatever. The folks that work there are not mechanics ad they don’t know what they are doing.


#13

The P0700 code is most likely set BECAUSE the sensor is bad, not because the control module is bad. The mechanic will change the sensor and re-check.


#14

Last question if I may, can you tell me if the speed sensor in question is fairly accessible? If it helps you, I can do many electrical repairs, just not engine or Tranny work, I’ve installed my own PCM, many sensors, fuel injectors, alternators etc.(not on this car but) I just can’t do “under the chassis” repairs as I am permanently disabled from a bad motorcycle accident (spinal damage). If i can reach it, I can install it.
Thanks for your valuable time as always. I do appreciate your wisdom and your candor.


#15

I don’t know for sure but I’d guess it is under the car - Murphy’s Law, you know. Good Luck!


#16

I understand completely, and what you say makes sense. To be honest, i typically pride myself on reading the character of a man, this place lets me bring in my own parts which is rare these days, but I am now suspect since they swapped out a module based solely on the scan and it obviously wasn’t the problem, it took 15 min $100 labor that he pulled out of thin air (I watched him think it up)…and leaving that boot I told you about on the side of my intake manifold cover unplugged wasn’t good either.


#17

You really are the best on the site my friend, wish I could repay the advice…do you know if I’m risking damage driving it to the shop, it’s just riding in “limp mode” correct? I’m not low on fluids or anything risking seizing something…


#18

and you’re so right, the Auto Zone people I’ve dealt with are pathetic…I watched a kid struggle for 30 min installing my battery…MY BATTERY! (he couldn’t figure out which mm the nut was)


#19

You and Mustangman have been so helpful, I’m very grateful for your assistance. Can you see where this speed sensor is on my 2011 GMC Terrain? I’m not being lazy, there is no Haynes or Chilton for this model.
Thanks again


#20

Yes, I think so. The lack of sensor confuses it but I think will get you to the shop OK.