I've posted this to the Expedition site before, but I don't think many people read there. I'm buying a 99 Eddie Bauer Expy and in 99 they discontinued, for the most part, the switch that enables you to drive it solely in 2WD. I say they were discontinued for the most part because I know for certain that very few 99' and up still had the option to drive their 4WD Expy in 2WD. Maybe this will be easier to explain:

97 - 98 4 X 4 switch...........99' - 02 4 X 4 switch

2WD................................
4AWD.............................. 4AWD
4HI................................. 4HI
4LO................................. 4LO

Can I change this switch so that I can run in 2WD. I like being able to have the ability to drive in just rear wheel drive. Thanks for your help!

 

Swap the T-case back to an older one. Put in and wire up the old style switch and you are done.

JMC

 

JMC,

I may be wrong here, but I don't think they changed the actual t-case through the years. I was looking up part numbers and I'm finding they are the same, including the actuator motors in the case. I wonder if the 4x4 system works when its grounded? For example, when starting a vehicle, the key turns the ignition and grounds it, then power is sent to...... I'm wondering if the 98 with the 2wd option on the switch is just a position on the switch that un-grounds the 4x4 system, then when you switch it into either 4AWD, 4HI, 4LO, that grounds the system and voila. Any thoughts?

 

JMC, I'm not sure if they changed the GEM module between '98 and '99, but I suspect they did. For '99 (when the 2wd mode disappeared) they would have also needed to get rid of the center axle disconnect too. For '97 and '98, the 2wd mode was a true 2wd, the a4wd mode locked in teh front axle and used the magnetic clutch coil in the transfer case, as well as a Torque-On-Demand relay (solid state) to engage the transfer case. The whole Control Trac system on the Expeditions was basically an up-scaled version of what was on the Explorer.

That being said, I don't think that the GEM in the '99-up Expeditions would recognize the other setting on the switch for 2wd, would it? (3.9 k-ohms for 2wd versus 1.5k-ohms for the a4wd setting) I'd be surprised.

Now, that being said, there is a way on the Expeditions that you can manually force the transfer case to disengage the front axle whether the switch is in A4wd or in 4 low: It's called the 'Brown Wire Mod' and has been used on all the 2nd Gen Explorers for a couple of years. Luckily, if you have a first-gen Expedition with the Control Trac AWD, it'll work for you too.

Basically, the short version is that you install a switch between the TOD/TCS relays and the clutch coil in the transfer case. The switch can be used to interrupt the signal to the transfer case clutch coil, thereby de-coupling the front and rear driveshafts. This mod will work in both auto/high range and low range, giving you a true 2wd when you want it, whether it's in high range or low range.

I haven't personally tried it on an Expedition, but as far as I can tell from the wiring, there's no reason it shouldn't work. All I need is a willing volunteer and a switch. Any takers?

-Joe