How to wire up for 2wd Low Operation...???!?!?

[marv_springer]

Guys,

Anyone mod'ed they electric shift Case/push button Controls for 2wd Low Operation?

Here's what I've got:
99 Tahoe
Vortec CPI 350
4l60E trans
246 electric shift case (has buttons for 2wd, 4Hi, 4Lo, and Auto 4wd)

I used to have a 94, and I did modify it for 2wd Low. But it had a 241 Lever shift case and that stupid electric/heater/air thingy that engaged the front end.

But what about the push button ones... Anyone done it?

Thanks,

Marv

 

[noJeepshere]

Replace the POS front driveshaft engager thing with a posi-lock, that'll do what you want. Yours is setup exactly the same as mine, and the only difference, IIRC, between 94 and 99 is the acuator became electronic instead of thermal.

 

[marv_springer]

Riley,

I'm thinkin' it's different for a couple of reasons:

1) Posi-lok's website only shows application up to 98. And they have a note on there for the "thermal" actuator. As you pointed out, mine's electric.

2) My low range (electrically actuated) will not engage with the front axle actuator plug unplugged. So, the tranfercase waits for the front CAD to engage before it does.

Was thinking about just going around the 4x4 buttons and just hotwiring the case somehow.

Anyone else...?!?!

Marv

 

[Jason4x4]

convert the t-case to a lever, then you can do whatever you want. and a posi-lock.

 

[AJMBLAZER]

You might call them. You have the same transfer case as earlier trucks in that body style. They might also be generically saying -98 because the pickup trucks body style changed in 1999 and some of the drivetrain did as well.

I've seen Posi-Lok's used in trucks with the electronic t-case and I don't THINK they had to do anything to the t-case to make it work.

 

[pauly383]

Thats the drivetrain in my 99 Suburban . Good question . I'm gonna go digging for it .

My thinking is something could be done to trick the computer into thinking the front is engaged ( kinda like the skip shift bypass harness on 'vettes ) .

 

[marv_springer]

My thinking is something could be done to trick the computer into thinking the front is engaged ( kinda like the skip shift bypass harness on 'vettes ) .

Exactly what I'm thinkin'.... All the wiring is there, just gotta know how to tell it what to do.

Marv

 

[pauly383]

I am running through all the SFA swaps I can find , becasue the answer may ly along those lines , and all I can find so far is "replace with 2001 HD manual lever np263" .

 

[daleearnhardt01]

Im not sure, but I would check and make sure that having the AutoTrac transfer case doesnt change anything, otherwise being a 99 doesnt make it any different than a 98. Im just not sure what having AutoTrac vs regular case means if anything; which it probably doenst.

 

[pauly383]

What autotrac means is the transfercase motor/encoder is in standby and when a wheelspeed sensor senses spin it puts it in 4wd hi and locks the front axle .

What I do know so far is the motor/encoder tells the computer what gear its actually in , the dash switch tells the computer what gear you've selected , and the 4l60e will change shift points based on transfercase gear .

Damn thing is tied together tighter than most wives

 

[marv_springer]

What autotrac means is the transfercase motor/encoder is in standby and when a wheelspeed sensor senses spin it puts it in 4wd hi and locks the front axle .

What I do know so far is the motor/encoder tells the computer what gear its actually in , the dash switch tells the computer what gear you've selected , and the 4l60e will change shift points based on transfercase gear .

Damn thing is tied together tighter than most wives

Interesting.... I didn't know how this "autotrac" thang worked.

If it's capable of doing that (on the fly...) seems like it would be cake to tell it to go to 2wd low, huh.... Just gotta know the language.

Marv

 

[noJeepshere]

Thats the drivetrain in my 99 Suburban . Good question . I'm gonna go digging for it .

My thinking is something could be done to trick the computer into thinking the front is engaged ( kinda like the skip shift bypass harness on 'vettes ) .

I just thought of this... find out how the computer knows how the front end is engaged (ie, does the actuator become grounded to signify engagement?) put a switch in the dash that mimics the actuator signal, put a posi-lok in the actuators place, and voila! the computer thinks it's in 4wd, but you have 2lo.

 

[pauly383]

Yeah , trick the front sensor somehow and use the posi lock .

Either way , there no turning the front driveshaft off though .

 

[BulldogK5]

Anybody find out anymore info on this?

 

[pauly383]

Anybody find out anymore info on this?

Unfortunatley I didn't . Unsure of Marv . Hes been booty fabbing all summer , and hasn't posted anything on it .

I figure I am never going to use my Burb in the dirt harder than getting my Fleetwood to the side of the lake , so I may let it go .