TD27T auto - resistor on speed sensor?

[keepwalkn]

hi guys,

sick of my terrano locking up as soon as you are "cruising" above 60km/h.
it won't unlock until you really squeeze the throttle and then it revs it's nuts off.

what I want to do is put a resistor in the speed sensor circuit to the auto trans ecu to make the ecu think that 75-80 is 60 and then lock it up...
the td27 simply doesn't have the torque to pull small hills at 60/1600rpm.

can this be done? any help would be appreciated - wiring diagrams etc.

thanks.

[phaedrus]

It might be worth adjusting the TPS, which in a D21 is on the top of the injector pump.

Also check that it hasn't got a broken wire as it comes out of the sensor itself - I had one that did this and was able to repair it by cutting into the sensor a little and soldering on a new piece of wire.

Otherwise you can wire up a 5 or 10k pot to it and mess around but I never found that to be very successful.

Cheers, P.

[keepwalkn]

already adjusted the TPS so that the shifts occur at a higher RPM.
the converter lockup is controlled by speed and trans temperature and lastly throttle position. the auto kick-down is activated by a switch on the accelerator pedal - you can hear it click as you press the pedal down.

does the auto ecu see the speed signal as voltage?
I want the lockup to work like normal in terms of unlock and trans temp, so those signals won't change, I just want to modify the speed the trans ecu sees...

[tweake]

i wonder if the system is similar to a patrol and you can manualise the lockup. ie switch it off/on when required
also do they run a "sport" mode on the gearbox at all or any overdrive?

[keepwalkn]

i wonder if the system is similar to a patrol and you can manualise the lockup. ie switch it off/on when required
also do they run a "sport" mode on the gearbox at all or any overdrive?

I was hoping I could use the speed sensor circuit and not just cut the TC lock power feed...people have reported problems with the box not locking automatically after they manually lock/unlock it.

edit: see here http://www.nissanpathfinders.net/forum/ ... ranny-mod/
this is db's mod but the problem was when you wanted the converter to lock again it wouldn't and you have to shut off the car and restart...

What about having a 3 position switch?
1: TCU controls the lockup
2: Manual lockup (sends 12v to the solenoid no matter what gear)
3: No lockup

[tweake]

have you got a manual or wiring diagram of the auto?
i've only got navara one here. it shows a revolution sensor as well as a feed from combo meter (gauges) which will be the speed info.
resistor will only work if it a voltage controlled system not a frequency controlled system.

[keepwalkn]

have you got a manual or wiring diagram of the auto?
i've only got navara one here. it shows a revolution sensor as well as a feed from combo meter (gauges) which will be the speed info.
resistor will only work if it a voltage controlled system not a frequency controlled system.

Yeh I have one...
Need to find that out...check out my last post tweake...thoughts?

[tweake]

i see there is also and engine rpm input.
with the patrol it could be tcm is not seeing the rpm change due to the lock up and stops using the lockup.

you could change the speed voltage/feq but i don't know what the revolution sensor on the auto box is for.

[tweake]

going by the navara one, looks like revolution sensor is the main one for vehicle speed with the speed from the gauges being a back up.
it sends out pulses. you may be able to use of the frequency conversion kits to change it.

[keepwalkn]

Edit:
I found this on the 240SX forums - They use the same gearbox.
REVOLUTION SENSOR TEST
1) Check resistance between revolution sensor terminals.
Resistance should be 500-650 ohms. If resistance is not as specified,
replace sensor.
2) Revolution sensor is a voltage generating sensor and
should be tested using a voltmeter set on AC scale. Check voltage
between ATCU terminal No. 25 and ground (Infiniti, 240SX and 300ZX) or
ATCU terminal No. 16 and ground (Pathfinder and Pickup), while driving
vehicle. Voltage should rise gradually relative to vehicle speed. At
zero MPH, voltage should not be present. If voltage does not rise
gradually, repair circuit as necessary.

That says to me I can use a resistor to trick the TCU?

Sent one of the guys on the Patrol4x4.com forum a message. He is cluey with the RE4R03 boxes...
I want to firm up the shift pressure too so I am looking at changing the dropping resistor to one of lesser resistance...Just need to find the bugger!

[keepwalkn]

Ok, I found the line pressure solenoid dropping resistor, this controls the line pressure for the shifting of gears in the transmission.