looking for duty C bypass info

[tahiti350]

Lately I've been using my legacy as my hunting rig (it's the 214K white wagon). It's taken me places that friends with 4x4's chose not to go, but I could really use a 50/50 split on the AWD.

I've been searching for the thread that tells which wire to put the switch in to de-power the duty C, but haven't been able to find it.

Can a get an assist?

Gary B>

[beatersubi]

I've been planning on doing this soon with the coming winter.
Here's the thread I followed: http://bbs.legacycentral.org/viewtopic. ... awd+switch The better info is in the USMB thread, though.
Basically, you interrupt the signal from the TCU to the duty-c solenoid effectively locking the transfer gears in AWD/4WD.

[tahiti350]

that's the thred and info I was looking for, much thanks!! should be 4x4 for hunting this weekend!

Just to confirm, the switch selects either the Duty C solenoid or ground, correct??

[beatersubi]

From my understanding, the switch would break the signal from the tcu to the sol for 4X4 and leave it in connected for normal operation. I believe grounding it from the switch keep the tcu from throwing a code.
Please double-check, though, as I'm not 100% on that and need to re-read it myself.

[Legacy777]

I would not recommend grounding the pin, like beatersubi mentioned the switch is simply opening the circuit which causes the duty c solenoid to be open and allow full line pressure to the rear.

According to this diagram, you could potentionally cut & hook the switch to pin 4 of the duty c solenoid and alternate that to ground. But without know exactly what the logic in the TCU is doing, I'd probably just leave it an "open" connection.

http://main.experiencetherave.com/subar ... _diag1.jpg

[tahiti350]

I wasn't talking about grounding the oin from the Duty C, but the signal lead that the switch will be in. Hoping to prevent the TCU throwing codes.

Anyone who has done the mod have the answer?

[beatersubi]

I thought I had remembered reading somewhere that grounding that signal from the tcu via the switch whilst interrupting the solenoid signal would keep the tcu from throwing codes.
I very well could be wrong, though.

[eulogious]

Just grounding that pin will NOT prevent the TCU codes. The TCU is looking for around 13ohms (+/- about 3 ohms) coming from the solenoid, and when it doesn't see that, it throws a code. To fix the TCU from throwing a code, you need to add in a resistor pack to fool the TCU into thinking that the solenoid is still there.

When I did mine, I wired in a DPST switch, so that when I flipped the switch it broke the connection to the TCU while at the same time open a new connection to the resistor pack fooling the TCU into thinking that the solenoid is still there when it was in fact disconnected. Worked great and I had no codes ever from this.

Now there is one thing to worry about with this, and that is accidentally hitting the switch when you don't realize it and then wearing out your clutch packs. So just be care to mount the switch where you can't accidentally bump it on, and you should be good to go.

I have since modded my TCU with some DCCD code and paddle shifters and installed a knob for that allowing me to select the how much power is tranfered to the clutch pack, so I no longer use this mod. But it worked great for the 4 months or so that I used it!

Here's the thread I used over on rs25, defcon is a good guy. He helped me out when doing my mod last year!

http://www.rs25.com/forums/f8/t99075-4e ... -lite.html

Lots of good pics and info in that thread...

Hope that helps clear up some confusion!

[beatersubi]

Thanks for posting that link. Lot of good info in that rs25 thread.

[beatersubi]

I think this thread contains enough pertinent info to be stickied. Mods?

[eulogious]

Glad I could help! It's good info to know!

At the time I had a 1990 Loyale with a 4EAT in it, so I had to find all the wires in a completely different car, and defcon helped me out with that. It a great mod to do for sure!

[beatersubi]

I just got home from the annual hatch patrol x-mas tree run up near crystal and can report with confidence that this mod is worth it for anyone who spends any time with their car off-road. I can easily see the benefit for rallycrossing, as well.

[Danny-G]

Would it be a good mod for snow drifting and mudding?

[Legacy777]

I think this thread contains enough pertinent info to be stickied. Mods?

Added to the sticky compilation thread

[beatersubi]

Would it be a good mod for snow drifting and mudding?

Yes.

Added to the sticky compilation thread

Thanks.

[ashergrey]

I'm preparing to do this mod on my 94 turbo wagon in advance of an extended desert off road trip. From what I'm able to gather, the duty C solenoid wire on the first gen Legacy should be the white with black stripe, correct?

Testing this wire I get 9.1 volts with the FWD fuse in and ~.1 volts with the fuse out, 1st gear selected on the lever and the throttle full open. That seems to meet the criteria from the later model FSM posted in the rs25.com thread.

[Danny-G]

Could I possibly use this mod to go rwd? If it locks the centre multi clutch pack, and I was to pull my front cvs but leave the hub ends, wouldn't that give me rwd?

[beatersubi]

Could I possibly use this mod to go rwd? If it locks the centre multi clutch pack, and I was to pull my front cvs but leave the hub ends, wouldn't that give me rwd?

I believe, yes, you can. Another member here (can't remember his username) recently did this with much success. edit: here it is
I would worry about transmission and rear diff durability, though.

[Legacy777]

I'm preparing to do this mod on my 94 turbo wagon in advance of an extended desert off road trip. From what I'm able to gather, the duty C solenoid wire on the first gen Legacy should be the white with black stripe, correct?

Testing this wire I get 9.1 volts with the FWD fuse in and ~.1 volts with the fuse out, 1st gear selected on the lever and the throttle full open. That seems to meet the criteria from the later model FSM posted in the rs25.com thread.

Yes, the white wire with black stripe should be the correct wire for the duty c solenoid.

[ashergrey]

Thank you much. I was pretty confident based on multimeter readings and examining the FSM pages but sometimes independent verification helps ease doubts.

[turbo970]

I'm preparing to do this mod on my 94 turbo wagon in advance of an extended desert off road trip. From what I'm able to gather, the duty C solenoid wire on the first gen Legacy should be the white with black stripe, correct?

Testing this wire I get 9.1 volts with the FWD fuse in and ~.1 volts with the fuse out, 1st gear selected on the lever and the throttle full open. That seems to meet the criteria from the later model FSM posted in the rs25.com thread.

Yes, the white wire with black stripe should be the correct wire for the duty c solenoid.

so if i tap into this wire with a 2 way switch i could use it for power mode?

[Danny-G]

Power comes from grounding a pin from the TCU.

[Legacy777]

so if i tap into this wire with a 2 way switch i could use it for power mode?

This was in the forum sticky

http://bbs.legacycentral.org/viewtopic.php?t=34807