CVT: D v. L

A forum for the Nissan Quest... minivan lovers unite!
RonBranam12
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Car: 2016 Nissan Quest SV

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Just curious as to when Low should be used in stead of Drive with this transmission. I know Drive is the normal operating mode. I have been in the habit of using low range on other cars when on a down grade to use the engine for compression braking. Is that OK with the CVT? Also, if climbing a grade would Low be appropriate? Both of these at slow speed of course. Less than 25 MPH.


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VStar650CL
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2004 Nissan Altima 2.5 S

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Yes, it's fine to use Low range on a CVT just as you would on a conventional A/T. The only difference is that the CVT is being locked into the lower range by software and not a mechanical gearset.

RonBranam12
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Joined: Fri Aug 20, 2021 6:48 am
Car: 2016 Nissan Quest SV

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Thanks. I wish there was a "Like" button. At Laguna Seca Raceway there some short 6% grades when Low comes in real handy.

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phmichel
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Car: 2013 Nissan Rogue S AWD
2017 Nissan Quest SV
Location: NW Oregon

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VStar650CL wrote:
Thu Oct 14, 2021 4:31 pm
Yes, it's fine to use Low range on a CVT just as you would on a conventional A/T. The only difference is that the CVT is being locked into the lower range by software and not a mechanical gearset.
VStar - I've noticed something: On my 2013 Rogue AWD if I hit the L button at like 40 mph, the OD goes off and revs go real high (like putting a MT in 2nd gear from 4th). But on our 2017 Quest if I do the same thing it seems to recognize the current road speed and compensates somehow by adjusting the RPM and matching it to road speed (it doesn't over-rev). I assume its part of an improved design or CVT firmware on the newer Jatco?

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VStar650CL
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phmichel wrote:
Sat Oct 16, 2021 10:31 am
VStar - I've noticed something: On my 2013 Rogue AWD if I hit the L button at like 40 mph, the OD goes off and revs go real high (like putting a MT in 2nd gear from 4th). But on our 2017 Quest if I do the same thing it seems to recognize the current road speed and compensates somehow by adjusting the RPM and matching it to road speed (it doesn't over-rev). I assume its part of an improved design or CVT firmware on the newer Jatco?
The gen1 Rogue TCM software was among the first ever used by Nissan, and some aspects of it were pretty primitive by later standards. It isn't exactly Jatco, either -- Hitachi makes the TCM hardware and also writes the firmware to a spec produced jointly by Nissan and Jatco. So when there's a fly in the soup, it's usually impossible to determine which of the 3 chefs let it land there. ;)

RonBranam12
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Joined: Fri Aug 20, 2021 6:48 am
Car: 2016 Nissan Quest SV

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A little off subject but...
Now that I've been driving around town, I've noticed a noise. When first accelerating (usually after backing up, but not always) and when decelerating into what I believe to be the last downshift, I hear what sounds like a belt slipping. Not a high-pitched squeal like fan belt, more like a burp. Both of these are sometimes, not all times. Any thoughts?

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phmichel
Posts: 260
Joined: Tue Jun 24, 2014 3:00 pm
Car: 2013 Nissan Rogue S AWD
2017 Nissan Quest SV
Location: NW Oregon

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VStar650CL wrote:
Sun Oct 17, 2021 5:46 am
phmichel wrote:
Sat Oct 16, 2021 10:31 am
VStar - I've noticed something: On my 2013 Rogue AWD if I hit the L button at like 40 mph, the OD goes off and revs go real high (like putting a MT in 2nd gear from 4th). But on our 2017 Quest if I do the same thing it seems to recognize the current road speed and compensates somehow by adjusting the RPM and matching it to road speed (it doesn't over-rev). I assume its part of an improved design or CVT firmware on the newer Jatco?
The gen1 Rogue TCM software was among the first ever used by Nissan, and some aspects of it were pretty primitive by later standards. It isn't exactly Jatco, either -- Hitachi makes the TCM hardware and also writes the firmware to a spec produced jointly by Nissan and Jatco. So when there's a fly in the soup, it's usually impossible to determine which of the 3 chefs let it land there. ;)
Ha! :chuckle: Well said. It's not really a "fly in the soup", just an observation.

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VStar650CL
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RonBranam12 wrote:
Sun Oct 17, 2021 7:44 pm
A little off subject but...
Now that I've been driving around town, I've noticed a noise. When first accelerating (usually after backing up, but not always) and when decelerating into what I believe to be the last downshift, I hear what sounds like a belt slipping. Not a high-pitched squeal like fan belt, more like a burp. Both of these are sometimes, not all times. Any thoughts?
That could be judder. If it is, the TCM will have detected it and you'll have a P17F1 or P17F0 stored. It could also be a loud or balky stepper motor in the CVT, a balky TC sprag-clutch, or something that isn't the CVT at all like a leaky active motor mount. Get it scanned with a trans-capable scanner and see what's in there.

RonBranam12
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Joined: Fri Aug 20, 2021 6:48 am
Car: 2016 Nissan Quest SV

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VStar650CL wrote:
Sun Oct 17, 2021 8:09 pm
That could be judder. If it is, the TCM will have detected it and you'll have a P17F1 or P17F0 stored. It could also be a loud or balky stepper motor in the CVT, a balky TC sprag-clutch, or something that isn't the CVT at all like a leaky active motor mount. Get it scanned with a trans-capable scanner and see what's in there.
I don't like the sound of that. Pun intended. I think it's time I took this info. to my mechanic. I hope he won't mind it came from the internet. BTW: Will the ELM 327 I received in the mail today show this?

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VStar650CL
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2004 Nissan Altima 2.5 S

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If you're hooked up with CVTz50 it will read both TCM (transmission) and ECM (engine) codes, so judder codes will definitely show up. It won't do other systems. If your mystery noise is from something like an ABS solenoid, you'll need a better package like Torque Pro that can do work support for all the systems in the car.

RonBranam12
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Car: 2016 Nissan Quest SV

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I did a bing search and none of the sites showing Nissan OBDII codes listed those two. Granted, none of these sites were official Nissan. Is there an official Nissan OBDII code list?
Hey, I'm trying to get into this technology. I admit, I'm a dinosaur. I just this uear got a smartphone.

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VStar650CL
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2004 Nissan Altima 2.5 S

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Nissan has always kept the judder codes sort of QT, they're "proprietary" and not OBD-II (although they are OBD-II compliant). They don't even turn on the MIL, and our instructions about them are to take no action about either one unless the customer complains about palpable tranny misbehavior. To explain what they mean, P1F71 indicates minor belt-slip (judder) was detected. The belt is probably okay but the Valve Body may need replacement. P1F70 is the "death code." It means the TCM detected major slippage, so belt damage is almost certain.


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