How to manually control the FAD

[jc99]

OK, well, it wasn't too hard to figure this out. If anyone opts to manually control the Front Axle Disconnect, here's how you can do it.

Pin 1 - DG/PK - 12V (Use an ignition 12v signal so it is not constant 12v)
Pin 2 - VT/DB - Not Used
Pin 3 - VT/DG - Ground when FAD lock is desired; Open when FAD un-lock is desired
PIN 4 - BK - Ground

Note 1: If Pin 3 is grounded, the FAD lock engages. If 12v from PIN 1 is subsequently turned off (Jeep is turned off), FAD will remain in the locked position.

Note 2: My application is that these axles are in a 2001 Jeep Cherokee. If you disconnect the FAD connector because you want to control axle manually, I have no idea if or what error codes the Wrangler ECU may complain about.

Hope this may help someone in the future.

Poking the thread.... Anyone do this on a Gladiator?

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[stylin7]

Currently waiting on some 4 position connectors that will allow me to create a jumper harness at the FAD motor, instead of cutting into the factory harness.
Only question outstanding is what signal is sent back to the Drivetrain controller on position 2 when the FAD is activated, I have a feeling it will be a ground signal. Once I confirm that I will wire one of my aux switches to relays to interrupt the ground to position 3 and provide the signal to pos 2 so the drivetrain controller doesn't throw an error.

Connectors should be here in about a week.

Looking forward to less wear on my clutch when backing my camper in to my driveway that has a significant incline at the apron.

 

[ChuckQue]

Following this…

 

[jc99]

Was just talking to the OBD Jscan app guys about adding the FAD control to their trail view page today but from the thread it sounds like that might not be possible. He is looking into whether he could add a button like they have for the lockers, swaybar, fan, ABS and winch mode. Would be nice to have an actual physical button in the car though for the FAD control to get 2WD Low. One thing he told me to try was using Jscan to fully disable the FAD and see what happens ie do you ge 2wd low range. At some point I will give this a go but truck is in the shop for an oil leak. If anyone else tries it before me let me know the results and I will report back to the Jscan guys.

 

[stylin7]

Connectors showed up earlier than expected.
Here is the results:
Transfer case in 2wd FAD disconnected:
Pin 2: 12v
Pin 3: ~6.6v
Transfer case in 4wd FAD connected:
Pin 2: Ground
Pin 3: ~3.3v

Other notes while testing:
Shifting from 2wd to 4wd with ignition on run and engine not running, the FAD motor can be heard engaging. Shifting back to 2wd from 4wd nothing is heard and pin 2 stays as ground and pin 3 stays ~3.3v.
Engine running shifting 4wd to 2wd, FAD motor is heard disconnecting and pin 2 goes to 12v and pin 3 to ~6.6v


Next steps:
Set up a relay to switch pin 2 on FAD from ground to 12v and a relay to provide 3.3v return signal to drivetrain controller to avoid faults.
Both relay activated via factory aux switch

My testing seems to be different from some info previously posted here.

 

[CoolTech]

Next steps:
Set up a relay to switch pin 2 on FAD from ground to 12v and a relay to provide 3.3v return signal to drivetrain controller to avoid faults.
Both relay activated via factory aux switch

Be careful.

Pin 1: Obviously IGN power (on when ignition is on - Jeep may or may not be running.)
Pin 4: Ground

No debate on those 2 pins.

In my experience, Pin 3 is the Lock signal. Grounding Pin 3 locks the FAD. Removing Ground from Pin 3 opens the axle.

In my application (axles in a Cherokee), I ignored Pin 2. I believe PIN 2 is the feedback to the ECU.

Pin 2: Ground = FAD is in locked position
Pin 2: 12v = FAD is unlocked

JMO, ICBW

 

[stylin7]

Be careful.

Pin 1: Obviously IGN power (on when ignition is on - Jeep may or may not be running.)
Pin 4: Ground

No debate on those 2 pins.

In my experience, Pin 3 is the Lock signal. Grounding Pin 3 locks the FAD. Removing Ground from Pin 3 opens the axle.

In my application (axles in a Cherokee), I ignored Pin 2. I believe PIN 2 is the feedback to the ECU.

Pin 2: Ground = FAD is in locked position
Pin 2: 12v = FAD is unlocked

JMO, ICBW

When removing the ground from pin 3 in you application, does the FAD motor activate to disconnect?

 

[CoolTech]

When removing the ground from pin 3 in you application, does the FAD motor activate to disconnect?

Yes, as soon as Pin 1 has power. Ground signal locks it; Removing Ground opens it. No movement/activation until Pin1 has power.

 

[stylin7]

Yes, as soon as Pin 1 has power. Ground signal locks it; Removing Ground opens it. No movement/activation until Pin1 has power.

Well looks like I am gonna build a harness to operate independently of the drivetrain controller and test further or just scrap the idea.

 

[Gaffer]

I would like to have 2-wheel drive low. Basically want to trick the computer when the Jeep is shifted into 4H or 4L that the FAD has engaged by bypassing the electric shifter circuit and not produce an error code. Anybody have or have access to a wiring schematic for the electrical plug that goes to the FAD unit.

Install hubs
https://www.4wd.com/v/jeep-wrangler-jl/locking-hub-kit/_/N-1sj00Zcm0pz
I have hubs on my TJ and have used 4 low with hubs not turned in on several occasions.

 

[Gaffer]

In the Good Old Days, when real Jeeps had Lock Out Hubs, we just left hubs in 2x4, shifted into low range. 2 wheel Lo on demand.. I thought I saw hub kits for TJs, JKs, might come for the JL

Here you go
https://www.4wd.com/v/jeep-wrangler-jl/locking-hub-kit/_/N-1sj00Zcm0pz

 

[jc99]

Wondering if you could just put a switch inline of one of the control wires that when switched off would make the computer think there is a problem with the FAD and force it to disengaged mode well the switch is in that state.

 

[Damien]

I have purchased a set of 2020 JL Rubicon Axles to put in my 86 Comanche. I have wiring kit for the lockers, and the front axle disconnect. Just need a diagram to hook it up. Thanks in advance

 

[CoolTech]

I have purchased a set of 2020 JL Rubicon Axles to put in my 86 Comanche. I have wiring kit for the lockers, and the front axle disconnect. Just need a diagram to hook it up. Thanks in advance

See my Post 30 to wire the FAD. The lockers are easier. 12v locks them, remove the 12v and they are unlocked.

 

[Damien]

Does anyone know where I can get the plug in for the fad

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