No 4wd

[Moe60]

OK so after reading around and doing some diagnostics I am pretty sure my control module is bad. I get no dash lights at startup and did have some battery issues just prior to losing 4wd.

My truck is not used a lot anymore, just chores and putting my little fishing boat in the water. My favorite launch sight does not have a ramp so I need 4 hi to get in and out of the water.

To get by and not spend any $$ I was thinking - since I have the BW1354 E t-case can I manually turn the t-case motor to hold the manually shifted t-case in 4 hi and leave it there, then use the brown wire in the t-case with a switch to just use the solenoid to go from 2wd to 4wd?

I know I will be turning the t-case at all times but gas mileage is not an issue because of little use and since the front axle is not engaged if the solenoid is not energized I should be OK on dry pavement right? No t-case chain issues? Any issues I'm not seeing?

Thanks in advance for any help, Moe

 

[RonD]

Not sure I am following you but I think the answer is no, on just a switch to go from 2WD to 4High.

The way it works now, or should work
The control module has 2 relays inside that reverses shift motors polarity, like power window motors, +/- rolls down the window, -/+ rolls up the window
Shift Rod in transfer case can not rotate 360deg, so to change from 2WD to 4high or 4low the shift motor must be able to turn in both clockwise and counter-clockwise directions.

How does shift control know when transfer case in is 2wd, or 4high or 4low?
Inside the shift motor there is a Contact Wheel, and 6 contacts, as the motor turns so does the contact wheel, and the contacts are opened and closed.
Lets call the contacts A, B, C and D
When A and D are closed and B and C are open then transfer case is in 2WD
A and C closed, B and D open then 4High
B and C closed and A and D open is 4low

The above combinations are made up for the point
So shift control module will "know" it is in 2WD or 4high or 4low when key is on by the contacts in the motor, so when you select another "gear" then shift control "knows" to move shift motor clockwise until "xyz" contacts are correct, or counter-clockwise.

This can't be done by a timer or just a switch because motor will move at different speeds depending on direction and voltage at the motor, vehicle voltage is 12.3v to 14.9volts at any given time.
You also have to remember which "gear" you were in to know which direction to move it.

If you wanted to do the manual control you could.
You would need two relays, 12v 30amp, and a 3-way toggle switch, on-off-on, momentary, so stays at OFF unless you hold it.
Then two or 3 LED lights for the dash.

Both relays are always Grounds to shift motor
When toggle switch is moved one way then 1 relay closes and sends 12volts on that 1 wire, other wire is a ground so motor moves clockwise.
Move toggle switch in the other direction and other relay sends the 12volts on its wire, so opposite direction
So you have both directions of rotation

You would then need to move motor to 2WD and test the contact wires, write down results, which are open and which are closed
Do the same for 4high, and 4lo
Then find a closed one that is ONLY closed in that "gear"
So A is only closed in 4high, NOT in 2WD or 4low
A would then be the 4high dash LED, its a contact, so if you run ground or 12volts thru it the light will come on when closed.

Find the same for 2wd, and 4low if you want

The brown wire would be hooked to Both Relays 12v out to shift motor but with a diode on each relay, that will save you having to use a 3rd relay
Brown wire is the internal clutch on transfer case, 12v engages clutch allowing easier shift rod movement, it doesn't disengage driveshafts

Good pictures here of shift motor and contact wheel and contacts: http://www.explorerforum.com/forums/index.php?threads/how-to-rebuild-4x4-shift-motor.123542/

 

[Moe60]

Hey RonD thanks for responding.

The way I understand the process when all stock items work correctly - you turn the dash switch to 4hi the motor turns the t-case to 4hi (connecting it to the trans) and the solenoid energizes to connect the front drive system.

I would be leaving the t-case in 4 hi permanently (just using the motor as a holder) and using just the brown wire and a new switch (and power supply) to energize or not the solenoid that activates the front drive system. Leaving everything else electronic disconnected basically by-passing the computer and motor altogether.

In theory that should leave me with either 2wd or 4 hi, no 4 low. And that's OK for my use.

Wadaya think?

 

[RonD]

I don't think the clutch pack would last very long, and you would end up with no 4WD

 

[Moe60]

Well nuts

Well you mentioned clutch packs and I had not thought about that so I did some more digging.

I found out that the 1354 t-case does actually have a solid mechanical connection front output to rear output when in 4 hi. I erroneous thought the connection was controlled by a solenoid. The brown wire in the 1354 system is for shift on the fly timing between the shafts not for controlling the connection between the shafts.

My theory might work on the 4405 t-case (used in some explorers) where the solenoid does actually control the connection.

The page I was reading that lead to my theory was not even about the BW1354e t-case!

Oh well, guess its off to the boneyard to get a module.

RonD - Thanks again for the input