Auto tranny acting wierd down hills.

**nissanaltimacrazyhorse** · 05-08-2008, 02:27 AM

My tranny seems to be acting really wierd or its really smart and its doing its job. When im going down a hill on road around 40mph maybe alittle more it shifts into 3 all by its self, skips 4th and it revs up to 3k and then when i get back on the gas to keep going is takes a couple of seconds and seems to shift hard back into 4th. Now ive only noticed this on one hill and it just seems odd because usually it just shifts to 4th, what do you think i have a problem stirring???

layonnn · 05-08-2008, 02:40 AM

The transmission shifts weirdly. Normal. Mine downshift when i let off the gas an coming up to a stoplight.

Flying Brick · 05-08-2008, 03:48 AM

The computer will attempt to shift your auto trans down if it senses you are coasting down a hill and accelerating with out being on the throttle. You can feel it do this going down steep hills if you take your foot off the gas let it coast and start gaining speed and just lightly tap your brake it will shift down a gear. But I have noticed sometimes on an exit ramp that is downhill it seems to get a little confused for a second when you are trying to speed up. I usually just back of the gas pedal for a second and it straightens out. This should be normal. Nothing to worry about. I think there is a mention of this feature in the owner's manual. I had to look this up myself when I first noticed it.

**nissanaltimacrazyhorse** · 05-08-2008, 04:40 AM

ya it just catches me off guard when it does it if its normal great its saving me some brakes. If not i have some serious tranny problems going on

sealevel · 05-08-2008, 04:44 AM

No problemo!

**RoverGGM** · 05-08-2008, 05:13 AM

Yes, just like the Brick pilot stated, the transmission is controlled by software called "Grade Logic".

To reduce gear "hunting" and unnecessary shifting, Grade Logic Control and Shift Hold Control systems are integrated into the shift programming of FJ automatic transmissions. Grade Logic Control alters the 5-speed automatic's shift schedule, reducing shift frequency while traveling uphill or downhill. Using inputs monitoring throttle position, vehicle speed and acceleration/deceleration, Grade Logic compares the operating parameters with a digital map stored in the transmission computer. When the system determines the FJ is on a hill, the shift schedule is adjusted to automatically hold the transmission in a lower gear for better climbing power or increased downhill engine braking.

Shift Hold Control prevents upshifts to higher gears (fourth and fifth) in repeated winding-road situations where the throttle is quickly released and the brakes are applied. This reduces disturbance to the chassis when entering a corner, and ensures strong power is available without a downshift. Shift Hold Control improves throttle responsiveness and reduces unnecessary shifting on curving roads.

**nissanaltimacrazyhorse** · 05-08-2008, 05:27 AM

Quote:

RoverGGM previously said:

Yes, just like the Brick pilot stated, the transmission is controlled by software called "Grade Logic".

To reduce gear "hunting" and unnecessary shifting, Grade Logic Control and Shift Hold Control systems are integrated into the shift programming of FJ automatic transmissions. Grade Logic Control alters the 5-speed automatic's shift schedule, reducing shift frequency while traveling uphill or downhill. Using inputs monitoring throttle position, vehicle speed and acceleration/deceleration, Grade Logic compares the operating parameters with a digital map stored in the transmission computer. When the system determines the FJ is on a hill, the shift schedule is adjusted to automatically hold the transmission in a lower gear for better climbing power or increased downhill engine braking.

Shift Hold Control prevents upshifts to higher gears (fourth and fifth) in repeated winding-road situations where the throttle is quickly released and the brakes are applied. This reduces disturbance to the chassis when entering a corner, and ensures strong power is available without a downshift. Shift Hold Control improves throttle responsiveness and reduces unnecessary shifting on curving roads.

Never knew that good info. So i guess i should only worry if it starts to slip.

wesayso · 05-08-2008, 05:31 AM

Quote:

RoverGGM previously said:

Yes, just like the Brick pilot stated, the transmission is controlled by software called "Grade Logic".

To reduce gear "hunting" and unnecessary shifting, Grade Logic Control and Shift Hold Control systems are integrated into the shift programming of FJ automatic transmissions. Grade Logic Control alters the 5-speed automatic's shift schedule, reducing shift frequency while traveling uphill or downhill. Using inputs monitoring throttle position, vehicle speed and acceleration/deceleration, Grade Logic compares the operating parameters with a digital map stored in the transmission computer. When the system determines the FJ is on a hill, the shift schedule is adjusted to automatically hold the transmission in a lower gear for better climbing power or increased downhill engine braking.

Shift Hold Control prevents upshifts to higher gears (fourth and fifth) in repeated winding-road situations where the throttle is quickly released and the brakes are applied. This reduces disturbance to the chassis when entering a corner, and ensures strong power is available without a downshift. Shift Hold Control improves throttle responsiveness and reduces unnecessary shifting on curving roads.

I knew my FJ was smart.

Hey Rover, your sig sounds like a Heinlein quote.

**RoverGGM** · 05-08-2008, 05:42 AM

Quote:

wesayso previously said:

I knew my FJ was smart.

Hey Rover, your sig sounds like a Heinlein quote.

Edited sig to reflect due credit (I forgot where I originally found it)

**DEWFPO** · 05-08-2008, 07:41 PM

This auto transmission is far too smart for itself. So much so, that I hope it's not it's downfall.

It shifts, a whole lot more than it needs to for me. In fact I often manually shift it because it can get spasms. I drive one road that has a speed limit of 35 mph and is fairly flat. The trans shifts into O.D. as soon as it hits 35 since I'm off the pedal. As soon as I touch the pedal to maintain speed, it downshifts, then upshifts, then downshifts, then upshifts and will continuously do this unless I don't touch the gas pedal at all or manually shift it into 4th. It shifts way too much under this condition. There should be a software reflash to correct this.

There's also this one road I travel on that has a fairly steep and long dip to it. At the bottom of the dip I get back on the gas to try to maintain speed coming up and as soon as I step on the gas, the trans will UPshift a gear, then immediately DOWNshift a gear to get the rpm back up. It does this every single time. The trans shifts so much more frequently than any other I've driven. I hope it doesn't wear out before 100K miles.

DEWFPO