Transmission difference problem?

[-JJ-]

I have recived my 94' 4EAT from japan, looks nice and doesnt smell burnt like mine , only problem is that it has, what i assume to be, a speed sensor in the front diff, my 92' 4EAT does not, it this going to cause major problems, or can i wire the box up the same as my original box, negationg the front diff sensor??????

Cheers
Jake

[oab_au]

Originally Posted by -JJ-

I have recived my 94' 4EAT from japan, looks nice and doesnt smell burnt like mine , only problem is that it has, what i assume to be, a speed sensor in the front diff, my 92' 4EAT does not, it this going to cause major problems, or can i wire the box up the same as my original box, negationg the front diff sensor??????

Cheers
Jake

Gid'ay mate I thought that it would have the sensor in the front diff, instead of in the transmission. Don't know why they would keep it there, it the latter boxs.

The wiring that runs down to the box has the sensor wires at the plug. You need to run these wires to the sensor in front diff. I am sure that Phil (b3lha) has sorted this out, before. Send him a PM. If he can't help, I'll scan the wiring.

Harvey.

[-JJ-]

I have a speed sensor in the old box, in the transfer case, there is the same sensor on the new box too, aswell as the sensor in the front diff??

[oab_au]

Originally Posted by -JJ-

I have a speed sensor in the old box, in the transfer case, there is the same sensor on the new box too, aswell as the sensor in the front diff??

Hi Jake, there are two speed sensors. The No.1 is inside the rear section, of both types of boxes. The No.2 speed sensor on the Aust box is inside the box, at the parking gear. In the JDM box, it is on the front diff.

You need to run the three sensor wires from the plug, that the box plugs into, to the sensor in the front diff.
Looking at the plug that the box plugs into, there is 16 holes, the sensor output is a white wire at pos. 15. The black is at pos.14, and the brown is at pos.8.

I don't have the diagram of the wiring, to the JDM/US No.2 sensor to tell what the colour is.

Harvey.

[-JJ-]

I don't have the diagram of the wiring, to the JDM/US No.2 sensor to tell what the colour is.

?? what do you mean ??

Do you mean the order they attach to the no2 sensor on the box??

also i have just pm'd Phil

[oab_au]

Originally Posted by -JJ-

I don't have the diagram of the wiring, to the JDM/US No.2 sensor to tell what the colour is.

?? what do you mean ??

Do you mean the order they attach to the no2 sensor on the box??

also i have just pm'd Phil

I don't have any info on the wiring of the No.2 sensor that is mounted in the front diff. I can't tell if the wiring for that sensor is connected through that plug, or has a different loom and plug for it. I just guess that the wiring colours are the same as the Aust sensor.

Harvey.

[-JJ-]

oh ok, i hope so, well maybe phil can help out.... Where are ya dude?

what would happen if i didnt wire it up??

[oab_au]

Originally Posted by -JJ-

oh ok, i hope so, well maybe phil can help out.... Where are ya dude?

what would happen if i didnt wire it up??

If it is not connected, the Limited Slip clutch won't work. You would spin the back wheels, on hard acceleration, or slippery conditions.
Its not a big deal to connect it.

Harvey.

[-JJ-]

k so i know which wires to run to the sensor, the sensor has three prongs on it, in which order do they conect?

Transmission:


The nubers represent the prongs on the sensor in the front diff, can you tell me which colour goes with the number?

[b3lha]

Hi Jake, Harvey.

Got your PM.

The speed sensors are not wire-for-wire compatible. I have an idea of how can be made to work, but have not tested it in practice.

I have the US manual which seems to reflect the JDM gearbox wiring (separate sensor). Pin 3 is power (Red/White), Pin 2 is ground (Black/White), Pin 1 is the speed signal (Yellow/Red). This speed signal feeds directly to Pin 11 of the TCU and Pin 11 of the ECU and several other places.

It's difficult to read the pin numbers on the scans in Harvey's locker, but it appears as though the signal from the Aussie/Euro (internal) speed sensor goes ONLY to the TCU and then a separate signal comes out of the TCU to feed the ECU, speedo etc. This output signal also connects back into the TCU on pin 11 where the JDM speed sensor connects.

My theory is that the TCU contains a circuit to modify the speed signal from the Aussie/Euro speed sensor into the sort of signal produced by the JDM speed sensor.

The input is pin 17 of B66, the modified signal comes out on another pin (can't read the number). This modified signal is then looped into all the places where the JDM signal connects (pin 11 of the TCU, pin 11 of the ECU etc.)

I think you need bypass this signal conversion step. Run a wire from pin 1 of the sensor and solder it onto the Yellow/Red wire that is connected to pin 17 of B66, disconnect the wires going into pin 17 and out from pin ??.

What do you think Harvey? You can see the diagram better than I. Is it plausible or am I talking nonsense?

Phil.

[-JJ-]

why would it not be possible to attach the speed sender cable from the new sensor to the tcu in place of the old sensor??? and then let the tcu send the signals out to the ecu etc? or will the signal from the diff speed sensor be differnt from the signal that would come out of the in box sensor?

[b3lha]

I think the JDM (diff) sensor and Aussie/Euro (internal) sensor produce different types of signals. Perhaps, being driven by different gears, they produce a different number of pulses per revolution - or perhaps one is a square wave and one is a sine wave. I don't know for sure. There must be a reason why Subaru wired them differently.

I assume that the JDM sensor is the same as the USA sensor described in my book: 5v square wave, 4 pulses per revolution of the sensor. Maybe Harvey's book explains the signal of the Aussie/Euro sensor.

[oab_au]

Originally Posted by b3lha

I think the JDM (diff) sensor and Aussie/Euro (internal) sensor produce different types of signals. Perhaps, being driven by different gears, they produce a different number of pulses per revolution - or perhaps one is a square wave and one is a sine wave. I don't know for sure. There must be a reason why Subaru wired them differently.

I assume that the JDM sensor is the same as the USA sensor described in my book: 5v square wave, 4 pulses per revolution of the sensor. Maybe Harvey's book explains the signal of the Aussie/Euro sensor.

Hi Phil, I am having troubles with the server, times out before I can get an image posted. Where about in the book did you find the output info.

Harvey.

[b3lha]

Originally Posted by oab_au

Where about in the book did you find the output info.

Book 6 (Electrical), Section 6.2 (Body Electrical System), Chapter 13 (Vehicle Speed Sensor)

[b3lha]

I had another look at Harvey's diagram on my computer at work which has a much better screen. I can see it clearly now.

On my diagram (USA/JDM), the speed sensor has a Yellow/Red wire that runs to pin a11 of the TCU, and branches off to the ECU, speedo, cruise control etc.
http://www.subaru-svx.net/photos/files/b3lha/33820.jpg

On Harvey's diagram (Aussie/Euro) the speed sensor has a white wire that goes into pin a17 . Then a Yellow/Red wire comes out on pin c6 and feeds into pin a11 of the TCU and branches off for the ECU, speedo, cruise control, etc.
http://www.subaru-svx.net/photos/files/oab_au/13771.jpg

I think the TCU has a circuit that a17->c6 that converts a "white-wire" Aussie speed signal to a "Yellow/Red-wire" JDM speed signal. These pins are not connected on either of my JDM cars. Since you now have a JDM transmission you need by bypass this circuit.

I would connect the white wire to the speed sensor in the diff. At the TCU end, I would snip it where it goes into a17. Then I would snip the wire coming out of c6 and solder the two together. Make sure to leave some wire hanging from the plug incase it doesn't work and you need to reconnect them.

That's my best guess, but it's untested. I would appreciate it if someone else would have a look at the diagrams and see if they agree. If you decide to try it, please post here whether it works or not.

http://www.subaru-svx.net/photos/files/b3lha/33817.jpg

Phil.