How to: The Comprehensive Brown Wire Mod Thread

[Wastedrubber]

sorry to beat a dead horse... 98 explorer; did the mod in the dash, with a lighted switch, and i do in fact seem to be in two wheel drive. I don't seem to be able to go back into 4auto though and the light never lights up on the switch. I first grounded to a screw in the dash then spliced in to the ground for the Cig Lighter. Still nothing. Can't figure out what the deal is, don't see any fuses that are burnt either.

Any advice? Thanks in advance.

 

[Wastedrubber]

nevermind, bad connection on one of the wires, all good now.

 

[Squirrels]

Another satisfied customer.......


.......except for my choice of rocker switch location. I mounted the switch horizontally on the right side of the black trim of the gauge bezel. Only problem was, as soon as I put the truck into "drive", the gear selector blocks my view of the switch

 

[fordpickupman]

Good write up....

Good job on the write up. It was totally clear until I read the questions and input from the rest of the of the thread......

The switch diagram was good.

The inside of the dash pics were very helpful.

I'll be doing this to my '99 soon.

 

[Stangyog]

Great Sticky!!!

Just did this to my '96 Sport. Works great!!!

 

[jsfordboy02]

I have the 4auto and I just want to add 4-hi, cant I just splice a wire from the brown wire (without disrupting the circuit) under the seat to one side of a on/off (not on-on) toggle switch and put power to the other side of the switch? When the toggle is "off" and in 4auto power will still be applied to the t-case when slippage is detected and when the toggle is "on" the aux power will be applied, thus engaging the "4-hi". Am I wrong?

 

[permbayer]

Okay I picked up a 5 speed manual 1996 Explorer yesterday and at first everything was fine in 2wd but since putting it in 4 wheel and then putting it back to 2wd something seems off. More noise and vibration. My simple question is does this indicate I might need to do this mod and is it the same process with a manual transmission?

 

[mustangfan35]

What do I do when I cut the brown wire and it is in a 2wd low

 

[Dono]

Quick question on where to cut the brown wire.
The wire appears to 'Y' from 2 brown wires to one behind the radio.
It looks like to OP cut 1 of the brown wires that are before the 'Y'. That confuses me.

I cut the brown Wire where it has become a single wire (Bottom of the 'Y'). Is this correct?

EDIT: I should have re-read the post. Its the brown wire that goes up from the Y to the left. oops. More soldering and shring wrap.....

 

[slickemhoundd]

a quick dummy question... The brown wire coming from the left of the dash is going to the top, is the brown wire from the right is jumping from the the middle prongs? obviously the bottom is power. Tryin to get 4h and would find a use for 2lo out of my 96.

 

[00whxploder]

Easiest mod yet. 15 mins tops.

 

[gr_elvis]

What about 1st generation Explorers does this work the same way for them? I have a 1994

 

[watt9386]

What about 1st generation Explorers does this work the same way for them? I have a 1994

No. 1st gens have 2 wheel drive normally, and go into 4 wheel drive when you press the buttons/use the tcase shifter.

Sent from my DROID RAZR using Forum Runner

 

[carlosromero]

pls.would you let me know if I may disengage the 4x4 system in a 2000 Explorer permanently?.This system,which I don't need, is giving me a lot of problems. I need to know if I may get rid of it without damaging other parts. Thank You

 

[dakota25276]

I have a 1997 ford explorer and the rear seats lay down in it when i lay them down there is a flap that can be raised up and there is a bundle of wires leading up and under the front driver side seat wouldn't it be easier to get to the brown wire from there

 

[DerekXLT]

Hi all,

I originally got interested in the BWM because my ’97 XLT was intermittently getting stuck in 4WD with the switch on 4WD Auto. It turns out that the problem was apparently due to slow leaks on both drive shaft speed sensors that reduced the transfer case fluid by 30%. Once I corrected this with new 7/8 x 1 x 1/16 o-rings and a fluid change, all was well.

However, in the meantime, I took a look at the GEM/TCSM/TOD/TCSR schematic (which I have attached below for reference). As a retired electronic engineer, albeit not automotive, something the OP said, despite an otherwise wonderfully helpful post, didn’t ring true:

Now, please note that the TOD relay is either on or off, and the Transfer Case Clutch is either engaged or disengaged. The relay and GEM do not vary the amount of power applied to the transfer case, they simply vary the DUTY CYCLE of the TCC. The transfer case is either engaged or disengaged at any given moment.

When you select 4 high from the switch on the dash, the GEM sends the signal to the Transfer Case Shift Relay to engage 4 high. This sends power directly to the Transfer Case Clutch Coil, essentially a 100% duty cycle.

When I first read this, I thought “why wouldn’t the designer use the same device (TOD) to generate the 100% duty cycle required for 4WD as is used to generate the lower duty cycle signal for 4WD-Auto?”

And as it turns out, he did. Although the Transfer Case Shift Relay (TCSR) does connect to the Brown Wire (see schematic), it’s sole purpose is to clamp the BW voltage so that it doesn’t go significantly below Ground (0V). That’s the function of the diode from Ground at TCSR-pin7 to Brown Wire at TCSR-pin 6. The TCSR is not capable of putting a high voltage (that is, 12V) on the BW. So why does it need to clamp the BW? Since the Transfer Case Clutch Coil (TCCC) is an inductor, it wants to continue drawing current out of the BW when the TOD has switched off. That current has to come from somewhere other than TOD – so it’s pulled through the diode. If the diode wasn’t there, there is the potential of damaging the TOD by creating a very large negative voltage spike on the BW.

Later, in a comment, the OP speculates:

Just thinking about this one.... if you insert the BWM switch between the TOD relay and the splice, then yes, 4high and 4low will act as normal even with the switch off. If you insert the switch between the splice and the TCCC, the system will not and cannot lock the two driveshafts together if the BWM switch is off. Transfer case range selection is otherwise unaffected.
-Joe

It doesn’t matter whether you break the BW before or after the spice as long as it’s somewhere on the path between the TOD and the TCCC. The controlling signal (from the TOD) will be interrupted and the Transfer Case will be in 2WD regardless of panel switch position. I confirmed this by cutting the BW between the TOD and the splice and observing that when the panel switch was moved from 4WD-Auto to 4WD that 1) 4WD was not activated, 2) the BW segment going to the TCCC had 0V (even though it was still connected to the TCSR, and 3) the BW segment connected to the TOD jumped from its nominal value up to around 6V as measured by my voltmeter. Note that it does not jump to 100% in any case, as far as I can tell.

Hopefully, some find this a helpful addendum to the OP’s great work. And if I’ve made any errors (entirely possible ), please let me know.

Cheers,
…Derek

 

[jrodmakrs]

thanks for the posts, I read that you can do this to an 02 model also? just want to be clear. thanks

 

[larryc1977]

brown wire mod?

this brown wire mod seems a like a little more work than you really need to go through. couldn't the same thing be accomplished by simply cutting the wires to the front drive line speed sensor and splicing them to the rear drive line speed sensor so that when in "auto 4x4" it always reads both drive lines at the same speed? poof auto 4x4 removed and manual 4x4 still functions as normal and you don't have to tear your dash apart and install extra switches. i havent tried it yet but it seems like a much easier way to me

 

[gijoecam]

this brown wire mod seems a like a little more work than you really need to go through. couldn't the same thing be accomplished by simply cutting the wires to the front drive line speed sensor and splicing them to the rear drive line speed sensor so that when in "auto 4x4" it always reads both drive lines at the same speed? poof auto 4x4 removed and manual 4x4 still functions as normal and you don't have to tear your dash apart and install extra switches. i havent tried it yet but it seems like a much easier way to me

First, you can't just tie in a pair of sensor wires like that. It doesn't work that way.
Second, even if it did work, the 4wd would still be active based on throttle position and load.
Third, your suggestion does not provide the ability to enable or disable the system as needed.

 

[kythri]

So, I'm likely going to get around to performing this mod to my '99 XLT, and if I'm reading around the Internets correctly, it will work, and therefore I'll also perform this mod, on my '00 Expedition EB.

My question, however, is in reference to the front axle being a "live axle" - can you educate me, or point me to a reference, about how the whole live axle setup works on an independent front suspension? Until I read this thread tonight, I had always assumed that a live axle was the same as a solid axle.

Thanks for the fantastic write-up!!