If your 4WD switch looks like this AUTO, 4HI, 4LO then...

[alfcapone]

hmm, maybe i remember it wrong..have to try it again!

 

[expl0der8]

I was reading through this post and doing some creative thinking and i have a question for the experts. Instead of using a switch to control the relay, splice into the current 4wd switch. This way you don't have to worry about flicking another switch if you want to go from 2wd to 4hi. I don't know if this is feasable, but it's a creative idea.

 

[tenikiwon]

Are you saying so that you'd have 2WD/4WD/4LO?

I like to have 2WD and then AUTO/4WD/4LO? Basically if I were to label my switch it would say, Front Axle.

 

[dogfriend]

Originally posted by expl0der8
I was reading through this post and doing some creative thinking and i have a question for the experts. Instead of using a switch to control the relay, splice into the current 4wd switch. This way you don't have to worry about flicking another switch if you want to go from 2wd to 4hi. I don't know if this is feasable, but it's a creative idea.

I don't think that it would be feasible to do this because of the way the 4wd (mode) switch works.

The switch has 3 resistors inside it. Each resistor value corresponds to one of the three 4wd modes. The switch connects directly to the GEM, which determines which mode you have selected by the resistance (voltage drop) in the circuit. The GEM then sends the appropriate signal to the transfer case clutch and the shift motor depending upon the switch selection.

The mod for 2wd works by cutting the power sent by the TOD relay (which is controlled by the GEM) so that it does not actuate the transfer case clutch. With the mod, the GEM still 'thinks' that you are in 4wd, but the power does not reach the transfer case, so it reverts to 2wd.

 

[expl0der8]

Originally posted by dogfriend
I don't think that it would be feasible to do this because of the way the 4wd (mode) switch works.

The switch has 3 resistors inside it. Each resistor value corresponds to one of the three 4wd modes. The switch connects directly to the GEM, which determines which mode you have selected by the resistance (voltage drop) in the circuit. The GEM then sends the appropriate signal to the transfer case clutch and the shift motor depending upon the switch selection.

The mod for 2wd works by cutting the power sent by the TOD relay (which is controlled by the GEM) so that it does not actuate the transfer case clutch. With the mod, the GEM still 'thinks' that you are in 4wd, but the power does not reach the transfer case, so it reverts to 2wd.

I would still put a relay in the brown wire path, but i would just use the signal from the 4wd switch to flip the relay. I haven't pulled it out to look at it to see if there is different wires for auto, 4hi, or 4lo, but if there is, it might be feasable.

 

[Hokie]

So you would disable your AUTO function? I don't quite understand on what you plan on doing. I did this mod this weekend and have already verified that the truck most definately stays in 2WD regardless of what the truck does (when the switch is tripped). I'll be driving to CO this weekend, so we'll see about any mileage gains (I don't expect much)

 

[tenikiwon]

Gas milage and Control Track

I don't think it will make a difference because the wheels are still turning, duh! and they turn the axles which turn the front drive shaft. THe only thing you are cutting it the actually t-case. I don't think it should make any much difference.

None that I noticed.

 

[dogfriend]

This is the schematic for 97 showing the 4wd Mode Switch. I don't know how you would control a relay to shut off the current from the brown wire because the switch only changes between 3 different resistance values.

If you want to see the other two pages of the schematic, check my photo album.

 

[expl0der8]

Originally posted by HokieBert
So you would disable your AUTO function? I don't quite understand on what you plan on doing. I did this mod this weekend and have already verified that the truck most definately stays in 2WD regardless of what the truck does (when the switch is tripped). I'll be driving to CO this weekend, so we'll see about any mileage gains (I don't expect much)

What i am talking about is wiring the switch part of the brown wire relay to the 4wd switch. This way you don't have to use a separate switch to switch the relay to allow 4wd. Basically it would turn the auto to all time 2wd with no option of auto 4wd. From what i see it's not possible. I didn't know if the 4wd switch sent a signal through 3 different wires, or through the same wire, didn't get around to actually looking at it. here is what the plan was.

switch = mode
AUTO = 2wd
4HI = 4HI (without activating another switch)
4LO = 4LO (without activation another switch)

 

[Mascman]

I DEFENITELY get better gas mileage with it in 2wd.
I know this for a fact since I am the one putting gas in it!

Maybe on a flat highway trip you won't notice it, but in hilly PA I notice it. I have 33s and 4.56s too so that may make a difference compared to a stocker with donuts.

It really helps mine out...especially with gas going up!

 

[sk1er17]

Is anyone paying attention to this thread still? I have a question: i have a 98 sport 4wd. If i put the switch in- does it mean i can now crank up my torsion bars for a little more clearance and only use 4wd when i need it?? Or will going over 2" still cause damage to my CV's when im in 2wd?

 

[Campo]

I would think they will still bind when turning, even without power to them. Defenatly would bind when put in 4WD...

 

[X24]

The only way to prevent damage to the CV's when lifting or lowering that much is to take them out.

 

[Doug]

The 2wd mod will have no effect on the cv's wearing out. The front axle is always engaged thus the CVs will always be turning. Alot of people make big deal about not going over 2" with a torsion twist but as far as im aware no one here has worn out thier CVs due to a torsion twist. i know a couple of people who are running more than 2" of lift out of a 2nd gen explorer via a torsion twist.

 

[sk1er17]

ok, now throughout reading this post- everyones talking about different color wires and different vehicles, needing a relay, or saying it works without a relay, putting in a light... etc.

On the 98- Can i put a switch with low guage wire AND an indicator light on the yellow wire? Or does the indicator go on a different wire (to tell when 4wheel is engaging).

And in doing that- will i have to turn my car off and on again to put it back in 4 wheel? And while in 2wd, ill get error lights on the dash right?

 

[tenikiwon]

I connected a regular lighted switch to the brown wire under the seat. i can flip it on at any time and it give me true 2WD and 2LO. The light is on when the switch is on, and brighter in 4WD or 4LO vs AUTO.

 

[sk1er17]

whoa, brown wire under the seat? we're not behind the dash anymore? i must've missed that page--- do you know what page of this thread the brown wire is talked about? (ive read it so many times)

 

[dogfriend]

Originally posted by sk1er17
ok, now throughout reading this post- everyones talking about different color wires and different vehicles, needing a relay, or saying it works without a relay, putting in a light... etc.

On the 98- Can i put a switch with low guage wire AND an indicator light on the yellow wire? Or does the indicator go on a different wire (to tell when 4wheel is engaging).

And in doing that- will i have to turn my car off and on again to put it back in 4 wheel? And while in 2wd, ill get error lights on the dash right?

If you use the yellow wire coming from the GEM, you can disable 4wd but you will have to turn the ignition off each time to get back into 4wd (reset the GEM) and you will get the flashing dash lights.

If you use theBROWN wire, it will do the same thing, except that you will not need to turn your truck off to reset the GEM to go back into 4wd and the dash lights should not flash. If you want to install an indicator light, you should use the BROWN wire.

 

[sk1er17]

Originally posted by tenikiwon
I connected a regular lighted switch to the brown wire under the seat.

dogfriend,
is the brown wire you're talking about behind the dash or under the seat? *if under the seat, are there more than one brown wires down there? i know quite a few wires are ran next to the seats.

Also, ok i connect the switch to the brown wire and have 2wd... my CV's shouldnt turn right? I thought the CV joints dont move unless the hubs lock in place-
To clarify (correct me if im wrong please)
When if AUTO, the CVs turn with 4% power all the time but the hubs are not locks, so essentually theres no power going to the tires until the sensor picks up slipping and the hubs lock into place. right? So with the switch in- the CV's wont be turning at all and because its true 2wd the hubs wont lock when the tires slip , hence no turning?

 

[dogfriend]

Originally posted by sk1er17
dogfriend,
is the brown wire you're talking about behind the dash or under the seat? *if under the seat, are there more than one brown wires down there? i know quite a few wires are ran next to the seats.

The brown wire starts at the TOD relay which is behind the dash next to the GEM. The same brown wire goes under the drivers seat (in a bundle) just before it goes thru the floor and down to the transfer case connector under the truck.

From what I read, everyone who has used the brown wire has made the connection under the seat, but theoretically (at least) it should be possible to make the connection as the brown wire leaves the TOD relay but no one has said they have done it that way


Also, ok i connect the switch to the brown wire and have 2wd... my CV's shouldnt turn right? I thought the CV joints dont move unless the hubs lock in place-

For a 98, you dont have locking (or auto) hubs, therefore your CV joints will still turn even if you disconnect the power to the transfer case clutch (by disconnecting the brown wire)


To clarify (correct me if im wrong please)
When if AUTO, the CVs turn with 4% power all the time but the hubs are not locks, so essentually theres no power going to the tires until the sensor picks up slipping and the hubs lock into place. right? So with the switch in- the CV's wont be turning at all and because its true 2wd the hubs wont lock when the tires slip , hence no turning?

The torque is transmitted by the transfer case clutch (inside the t-case). The t-case clutch is turned on and off by the GEM via the TOD relay (the yellow wire is the signal from the GEM, the brown wire is the current supplied to the t-case clutch). The hubs, CV joints and front driveshaft will be turning regardless of whether the switch (in the brown wire) is on or off. If the switch is off, the t-case clutch will not have power, therefore it will not engage according to the GEM program, therefore no torque will be transmitted to the front axle, but the hubs, CV joints and driveshaft will still be along for the ride.