Dont buy 550 navara

[apk47]

As we all know the V6 7 speed transmission is calibrated so that it upshifts at approx 1500 rpm when in 1st in manual mode, which is frustrating and it also has the unsafe behaviour of up-shifting when descending down hills. I have found you can fix this by implementing a work around that allows 4 low to be selected and manual mode to work as it should.
Basically the Navara’s have an electric transfer actuator device , which is a rotary actuator that rotates the shift rod inside the transfer case. There is a DC 12V motor and plastic gearbox arrangement that allows the shift rod to rotate through ¾ of a turn total travel, from 2H to 4LOW.
When the transfer case is in 2H the slot in the shift rod is in a vertical position. When the transfer case shifts to 4H it does so by rotating the shift rod ¼ of a turn clockwise. When the transfer case shifts to 4LOW it rotates another ½ of a turn clockwise.
On the transfer case actuator housing there is a connector which has 7 wires. The orange wire (pin23) goes to one of the motor terminals and the grey wire (pin24) goes to the other terminal.
When 12V +ve is applied to the grey wire and 12V gnd to the orange wire the transfer case actuator moves from 2H to 4H to 4LOW. (which takes less than 3 seconds, and should only occur when the engine is idling, the transmission is in neutral and your foot is on the brake)
Similarly when when 12V +ve is applied to the orange wire and 12V gnd to the grey wire the transfer case actuator moves back from 4LOW to 4H to 2H. (which again takes less than 3 seconds)
So what I have done is to cut the orange and grey wires and run wires up into the cabin, and fitted momentary switches so that I can change the motor polarity and manually shift the transfer case from 2H to 4LOW or back from 4LOW to 2H. (This works because the shift rod has fixed mechanical stops at each end of travel so that the motor stalls when it reaches either end of the ¾ range of motion. )
Effectively this is exactly the same as manually pulling on a transfer case lever for a 4WD that has one like a Patrol or D22.
Basically you never touch the 4WD selector on the dash from the 2H position as you are just applying electrical power to the transfer case actuator to initiate a manual change without the computer knowing.

So the procedure is:
drive to a 4WD track, and when you want to shift to 4LOW.
Follow these steps to select 4LOW
1. Let engine idle
2. Shift the transmission to neutral position
3. Put your foot on the brake.
4. Press momentary switches for 3 seconds only, (with the polarity 12V+ve on grey wire This will select 4LOW)
Drive around in manual mode or auto and everything behaves just how it should.

When you want to go back to 2H
Follow these steps to select 2H
1. Let engine idle
2. Shift the transmission to neutral position
3. Put your foot on the brake.
4. Press momentary switches for 3 seconds only with the polarity 12V+ve on orange wire (This will select 2H)

I have been using this for several months and I will soon be adding a couple more switches so that I can set everything back to std with a flip of a switch inside the cab, (which is good as this is the only way you can use 4H mode.) or press momentary switches and get a true low range manual mode where I can sit on 4000rpm and the transmission will stay in first gear if desired.


See pics below.

Thanks for the great idea. Since this is an older post, it appears the picture links are no longer valid, would it be possible to repost the pictures?

Thanks in advance
Andrew.

 

[Harris751]

Hi All,

Sorry to drag up an old thread. I'd really like to do this mod.

All the links to the photos are no longer working.. can anyone share the photos of the wiring and switches?

Is the grey and orange wire completely isolated from the computer before the voltage is supplied?

Any help would be awesome.

 

[Old.Tony]

I've tried to retrieve the images from the Way Back Machine but they're unavailable. We'll have to hope that @raptorthumper still has them and can repost them.

 

[apk47]

Hi All,

Sorry to drag up an old thread. I'd really like to do this mod.

All the links to the photos are no longer working.. can anyone share the photos of the wiring and switches?

Is the grey and orange wire completely isolated from the computer before the voltage is supplied?

Any help would be awesome.

I just did the mod and it works! (Last night)

Yes, the grey/orange wires need to be isolated from the computer if you use external power source. I did this via a second switch so you could use it as default or use the modification.

I ran 4 wires back into the cabin, cut the actuator orange and grey wires near the plug connecting to actuator as I couldn't easily get access to the wires elsewhere along length but not right at the end, so I had some length to play with. In the end ran longer wires to achieve this.
In the cabin I also ran 2 wires from the battery via a fuse.

I purchased a small black pastic box from jaycar (deeper one was necessary) to house the 2 switches cutting out the shape of the switches to mount them. Drilled holes and filed it flat.
To change to 4lo, i turn car on, put into neutral and apply brake. The change sw1 from default to custom. Then depress switch 2 down for a few second (can hear it work in the cabin).
When switching back to 2wd, i do the following, with car on, put into neutral, apply brake and push switch 2 up for 3 seconds. Then switch switch 1 to default again.

Switch 2 is normally in middle neutral position unless depressed up/ down.

 

[Harris751]

I just did the mod and it works! (Last night)

Yes, the grey/orange wires need to be isolated from the computer if you use external power source. I did this via a second switch so you could use it as default or use the modification.

I ran 4 wires back into the cabin, cut the actuator orange and grey wires near the plug connecting to actuator as I couldn't easily get access to the wires elsewhere along length but not right at the end, so I had some length to play with. In the end ran longer wires to achieve this.
In the cabin I also ran 2 wires from the battery via a fuse.

I purchased a small black pastic box from jaycar (deeper one was necessary) to house the 2 switches cutting out the shape of the switches to mount them. Drilled holes and filed it flat.
To change to 4lo, i turn car on, put into neutral and apply brake. The change sw1 from default to custom. Then depress switch 2 down for a few second (can hear it work in the cabin).
When switching back to 2wd, i do the following, with car on, put into neutral, apply brake and push switch 2 up for 3 seconds. Then switch switch 1 to default again.

Switch 2 is normally in middle neutral position unless depressed up/ down.

Awesome, thanks for the pics.

Has anyone worked out if there is a feedback signal from the selector that we could read with an Arduino?

Could make a little control unit with a touch screen that controls everything automatically.

Also, I am the only one who's doing this with a 4cyl? My facelift yd25 has all these same issues.

Chris

 

[Harris751]

I did this mod today on my 2010 facelift 2.5
Mechanically it works, but I get the 4wd light on and flashing low range light that won't clear now.

 

[Old.Tony]

Have any other plugs on the gearbox been removed? The 4WD light and 4LO flash are indicative of the sensor feedback being missing.

I've checked the manual and the transfer cases on the YD25's RE5 gearbox are not the same as those on the V9X's RE7 gearbox. I haven't gone over the wiring diagrams for each but they may not have used the same coloured wires in each - so the instructions for the STX550's transfer case may not be appropriate for the 4 cyl car.

 

[Harris751]

I've checked the wiring diagram further. The RE5 transfer case has the same orange and grey colour wires. I didn't disturb any other wires. Looking further into it, there is 4 position switches built into the control motor that report back to the TCU, maybe it doesn't work on the RE5.

 

[Old.Tony]

If you return the wiring to the original state, does this fix the problem?

 

[apk47]

I've checked the wiring diagram further. The RE5 transfer case has the same orange and grey colour wires. I didn't disturb any other wires. Looking further into it, there is 4 position switches built into the control motor that report back to the TCU, maybe it doesn't work on the RE5.

Did you hold down the button for the full 3 seconds or even a bit longer so it turn the actuator has time to fully rotate and hit the end stop?
If so, can you then put it into drive and move forward?
If you are able to do this, can you tell that you are in 4lo by the speed/revs /gear?
I found sometimes it flashes off i doesn’t hold It down long enough (now i wait until the light shows just the 4wd on the dash). Another time, i has to load/ unload gearbox so moving forward was necessary to stop flashing.
in which case i would go back to 2wd and start again.

Andrew

 

[Harris751]

Not really to sure at this point what's happening. With everything back to stock I have a solid lite 4wd light and the VDC light on. Have tried above suggestions but still the same.

 

[Old.Tony]

Could an ABS sensor have started to fail? Well, maybe not fail, but if a bearing starts to disintegrate, the debris (metal + grease) can get stuck in the teeth of the ABS ring and make the car think the ABS system has a fault. This will trigger the 4WD and VDC issues.

It's usually the front wheels. Do your bearings sound ok? Is the sound of the car going around a left hand corner precisely the same as going around a right hand corner, or is there a new subharmonic you can just hear? This is a sign one of your wheel bearings is on the way out. I've had to replace mine before (362,000km on clock now).

 

[Harris751]

Could an ABS sensor have started to fail? Well, maybe not fail, but if a bearing starts to disintegrate, the debris (metal + grease) can get stuck in the teeth of the ABS ring and make the car think the ABS system has a fault. This will trigger the 4WD and VDC issues.

It's usually the front wheels. Do your bearings sound ok? Is the sound of the car going around a left hand corner precisely the same as going around a right hand corner, or is there a new subharmonic you can just hear? This is a sign one of your wheel bearings is on the way out. I've had to replace mine before (362,000km on clock now).

No bearing noise to speak of.

I have started checking voltages at the TCM pins inline with the workshop manual. The position signals from the actuator are not what they are meant to be. I'm wondering if I have done some damage inside the actuator.

 

[Harris751]

All fixed and mod is working well.

Long story short, the drive shaft from the actuator can do a full 360 rotation and can be fitted to the transfer case 180 out. Through testing the voltages at the TCM I was able to establish this and rectify.

So can confirm that this works on the 2.5 facelift model as well.

 

[Cowboy550]

Hello All the Trend is don’t buy a 550 Navara.
My Stx550 is 9yo 2012, amazing DC, unbelievable at towing the 7 speed auto is flawless, so comfortable, awesome sound system and display, for me it’s all about the power but dam is a very nice saddle.

when you compare a STX550 to a D22 Im scratching my head in wonder .... really ? I do agree down hill decent would be nice, the fix offered here is fantastic and I take my hat off to you for Aussie engineering. But I wouldn’t go scrub bashing in 70k stock Stx550.

I found low 4wd first gear so slow being a 7 speed. when your towing 3 ton around the high country you understand the auto and it amazing capabilities, would I buy a STX550 again if I could turn back the clock ? absolutely I would

I read all your posts
thank you for the entertainment

 

[Harris751]

My final solution with the switches. I know this won't be everyone's cup of tea, but I like the simple utilitarian look and functionality.

 

[Jim_Zhu]

Hi all,

Thanks for the great insights and pleased to see so many knowledgeable guys here.
I recently bought a 2013 stx550 and was quite happy with the general on-road performance(Unable to do offroading and camping due to the current lockdown).
I only had humble experience on 4WD and is new to this forum.
After reading through all the posts here in this thread, I guess I had a few thoughts that I would like to share and consult with you gents more experienced members here:

1. Given the situation under 4LO, the tranny will upshift from 1st to 2nd at about 1800rpm, my question is: Practically, when going a steep downhill start from idle in 1st gear LO, if we don't push the accelerator and just let the vehicle crawling, is it gonna accelerate itself to 1800rpm and trigger an upshift to 2nd gear LO, hence make it unsafe? If it can, how steep the downhill needs to be or how much load it needs to carry? I did a test on a relatively steep ramp at a car park(with 2adults and no extra load), the vehicle is just crawling constantly at idle speed(800rpm in 1st gear LO) when going down that ramp. So I doubt it will be very hard to let it accelerate itself to 1800rpm in 1st LO if we can be patient not pushing the accelerator downhill.

2. Given Nissan keep emphasizing this upshifting is in-line with their design, and it will NOT upshift in 2H and 4H(I've also tested this to verify). I'm trying to think if that explanation can make some sense anyhow. Coz, if they didn't deliberately make this design and apply to 4LO, why would 4LO has different tranny behaviour than the other 2 modes(2H and 4H)? I guess we need to suss out this especially for those who want to apply the mods to disable the upshift.

Looking forward to some replies and I'm just trying to not let people here overreact on this. Don't get me wrong, I'm not trying to say this is a good thing, but just not that too bad. The impression I got after reading through all the 10 pages of discussions here has indeed make me feel a bit frustrated. But maybe, we have amplified the issue!

Regards,
Jim

 

[Old.Tony]

Hey Jim,

Down a steep incline when you're offroad you can easily accelerate. Engine braking is important to try and keep the brakes cooler (you're often dunking the car through water, and you don't want red-hot discs). We've been down an incline where the gravel dislodged by the car travelled faster down the hill than the car did (Boundary Rd, Nundle). That was 1st gear 4LO with brakes on constantly! The slightest release of the brake caused the car to accelerate quickly. 4HI would have made the car even harder to hold on the hill. Too high a speed would have resulted in a shifting of the surface under the wheels causing an uncontrolled descent.

As for the different behaviour - not sure, I've not seen the TCM programming (which would be responsible for this). In the Nissan 370Z (where your gearbox came from) there might be a function that the TCM is made aware of (like ECO or TCS) and this is what's causing the issue because (erroneously) the same code is used for 4LO.

 

[Jim_Zhu]

Hey Jim,

Down a steep incline when you're offroad you can easily accelerate. Engine braking is important to try and keep the brakes cooler (you're often dunking the car through water, and you don't want red-hot discs). We've been down an incline where the gravel dislodged by the car travelled faster down the hill than the car did (Boundary Rd, Nundle). That was 1st gear 4LO with brakes on constantly! The slightest release of the brake caused the car to accelerate quickly. 4HI would have made the car even harder to hold on the hill. Too high a speed would have resulted in a shifting of the surface under the wheels causing an uncontrolled descent.

As for the different behaviour - not sure, I've not seen the TCM programming (which would be responsible for this). In the Nissan 370Z (where your gearbox came from) there might be a function that the TCM is made aware of (like ECO or TCS) and this is what's causing the issue because (erroneously) the same code is used for 4LO.

Hi Tony, thanks for sharing the insights. I guess the situation you described with a bit of loose surface gravel is somewhat similar to sand driving, in which letting the sand move faster than the car, or in other words, braking the car to make it move slower than the sand is also unsafe. I'm curious to see practically, how much impact this upshifting behaviour in 4LO will have to different offroad situations. By then, I shall come back and share my experience with our community here.

Cheers,
Jim

 

[AaronOM]

Gday guys.
Very keen to do this wiring mod to my 2011 stx550. Love a good 4x4 trip but the only thing holding me back in this upshift issue, pretty much rules out any wet steep tracks where brakes wouldn’t be enough.
Unfortunately I am a complete novice when it coming to any auto elec kind of work. Would anyone be able to post up a step by step guide? And any extra photos would be a huge help.
Coming into a bit of free time so keen as to get this fixed up so I can get out and about!
Cheers guys.
Aaron.