Nissan Mistral auto box ECU

[paulp]

Hi

Is any one on here breaking a Nissan mistral 2.7td auto.
I am looking for the auto gearbox ECU, the one behind the O/S rear quarter trim by seat 6/7, for sale?

The symptoms are not holding torque lock in overdrive so instead of 2500 RPM " 70mph its 3000 RPM plus.
Newer Terrano have the ECU under the dash board behind the stereo system.

Thanks in advance

Paulp

 

[macabethiel]

70 mph in top gear?

Is this a new issue? If it is ignore comments below.

As I recall our r3mR was on the cusp of dropping down a gear at around 70 mph so I used the Eco switch to change up earlier - not sure yours has one.

Do you have a switch for Eco/Power if you have that will shift the gear range slightly as can a change of auto trans fluid.

Likewise are you talking laden or unladen as load will again make it go for higher engine rpm at any given road speed.

Lastly any drop off in engine power will also make it drop a gear. From my memory the Nissan Gearbox Brain is a fluid block controlled system with a simple electric kick down switch, there might also be some vacuum linked solenoids - check the fine hoses if yours has such a solenoid.

The later more modern solenoid shifters are controlled electronically with a connection between the engine ECU & the Gearbox ECU some systems are a sort of hybrid as ECU control took over the Gearbox Brain mounted in the gearbox itself where gear change points are governed by fluid pressure / engine load alone.

 

[paulp]

ECU

Hi thank you.
The ECU is electronic and the torque lock is controlled by the ECU.
On a previous one I could see the resistor burnt out. The one on it now looks more modern as it looks to have a CPU like a computer. It does have a mode switch and it makes no difference in what mode it is in.
The diagnostic mode also runs on start up and shows no fault in normal function.
Oh well the search goes on......of I could find the link led ECU it may be able to get repaired

Thanks for the response

Regards Paul

 

[elty001]

Banshee has just broke an auto,maybe he can help you out:nenau

 

[macabethiel]

Hi thank you.
The ECU is electronic and the torque lock is controlled by the ECU.
On a previous one I could see the resistor burnt out. The one on it now looks more modern as it looks to have a CPU like a computer. It does have a mode switch and it makes no difference in what mode it is in.
The diagnostic mode also runs on start up and shows no fault in normal function.
Oh well the search goes on......of I could find the link led ECU it may be able to get repaired

Thanks for the response

Regards Paul

Still not sure if this is a new problem you have encountered or is it how the vehicle was when you bought it?

The Mode Switch should definitely make a difference, at least mine did- I can't remember how mine actually operated is it something you can check perhaps?

I am a little confused when you say it is not holding the Torque Lock in overdrive. Do you mean the Torque Convertor lock is not locking up solid or is it dropping a gear as it will not sustain that speed in overdrive top if my question makes sense.
On my r3mR if you switched the overdrive on that did not mean it would always be in overdrive top. The gear selection was always load dependent be it an incline, road speed (air resistance), load carried & throttle position. Could be as you suspect the gearbox ECU.

 

[paulp]

ECU

Ok thank you.
The mode switch on the mistral is normal power and hold, never really could tell the difference,but have never towed anything heavy.

The ECU is more than likely the fault
The thing is the truck needs a couple of jobs doing and four tyres and if the gearbox is US I will look to sell on as spares or repair.

Ty for your input

Paul

 

[Banshee]

Ok thank you.
The mode switch on the mistral is normal power and hold, never really could tell the difference,but have never towed anything heavy.

The ECU is more than likely the fault
The thing is the truck needs a couple of jobs doing and four tyres and if the gearbox is US I will look to sell on as spares or repair.

Ty for your input

Paul

Let me know if you want to get rid :thumb2

 

[Barrbeast]

Terrano autoboxes are all (for the R20 at least) lighter duty versions of the Trol's RE4R03A transmission (Terrano has the RE4R01A box) so they're all transmission ecu working through electric solenoids with a throttle position sensor.

Not unknown (especially with older boxes) for the torque converter lockup to stop working properly. A lot of folk have spent time trying to sort it but with varying degrees of success. Easiest solution though is to fit a manual lockup switch if you can find the right cables leading from the ecu, that's what I did on my Trol and it's great as you can control when it locks up and keep it there (I can get lockup in 3rd when I've got OD off). I can point you to the Trol forum threads if that's of interest.

First thing you can do though is rule out an issue with the lockup system. Disconnect your throttle position sensor, this will make the ecu go to default mode based on speedo and revs. If it starts going into lockup you know it's not the lockup system at issue.