V8 swap transfer case questions

[Shayzar7]

Hey all, new to posting on TRS but not new to rangers, I came from the old FRF days. Anyways, I have a transfer case question. If someone can either answer it of point me in the right direction that would be great! So here’s the scoop. My truck is a 1999 3.0 auto 4x4. I’ve just dropped in a 5.0 and trans from a 2000 explorer but decided to keep the electric shift transfer case so I picked up a case from a 2000 F150 with the electric shift. I did not realize the wording for the shift motor is part of the 3.0 engine harness. Does anyone have any info on getting this swap to work as far as wiring and electronics goes? I was under the impression that the 4x4 system was independent of the main computer system. Thanks in advance!!

 

[dvdswan]

Welcome to the site. I don't have an answer. But you might find it here... Transmission, Transfer Case & Driveshaft - The Ranger Station

 

[RonD]

Yes, 4WD system is separate from the engine computer system

In 1999 Ranger(1995-2000) the GEM Module behind the radio, and behind it, the dual relay box, controlled the transfer case shift motor
Those wires to the shift motor were probably attached to old trans wiring harness not sure on that, but they were a separate harness that ran to the GEM Module area in the cab


1999 4WD wiring diagram below

In the diagram the dual relay box is called "electric shift control module"
It is literally just 2 relays in a box, but it powers motor part of the shift motor
As said it is located behind the GEM on the firewall
In the 1995-2000 Rangers the Dash switch, GEM, relay box rarely failed, shift motor was what usually failed

The F-150 transfer case shift motor is exactly the same as the Rangers, same wiring and plug in, same control
So plug and play once harness is available

Just FYI
Electric clutch in transfer case was dropped and no longer needed once front hubs were locked full time, Live Axles
It was there to shift from 2WD to 4high while driving when using Automatic locking Hubs, to RPM match front and rear driveshafts

 

[Shayzar7]

Yes, 4WD system is separate from the engine computer system

In 1999 Ranger(1995-2000) the GEM Module behind the radio, and behind it, the dual relay box, controlled the transfer case shift motor
Those wires to the shift motor were probably attached to old trans wiring harness not sure on that, but they were a separate harness that ran to the GEM Module area in the cab


1999 4WD wiring diagram below

In the diagram the dual relay box is called "electric shift control module"
It is literally just 2 relays in a box, but it powers motor part of the shift motor
As said it is located behind the GEM on the firewall
In the 1995-2000 Rangers the Dash switch, GEM, relay box rarely failed, shift motor was what usually failed

The F-150 transfer case shift motor is exactly the same as the Rangers, same wiring and plug in, same control
So plug and play once harness is available

Just FYI
Electric clutch in transfer case was dropped and no longer needed once front hubs were locked full time, Live Axles
It was there to shift from 2WD to 4high while driving when using Automatic locking Hubs, to RPM match front and rear driveshafts

Okay that is all really good info thank you!! As for the clutch in the transfer case I don’t think I have to worry too much as I have converted to manual lock outs, but that’s my assumption so feel free to correct me if I’m wrong.

 

[RonD]

As long as you don't try to shift in to 4high while moving with front hubs unlocked there will be no grinding
When hubs are locked front and rear driveshafts are spinning at the same RPM in the transfer case, so 2WD to 4high needs no RPM matching, that was only needed with Automatic Hubs

If front hubs were unlocked then front driveshaft would be at 0rpms so if you tried to shift into 4high while moving........grinding until chain and driveshaft match rear driveshaft RPM
Electric clutch engaged chain drive to spin it up to match RPM, kind of like a synchromesh "gear"

 

[Shayzar7]

As long as you don't try to shift in to 4high while moving with front hubs unlocked there will be no grinding
When hubs are locked front and rear driveshafts are spinning at the same RPM in the transfer case, so 2WD to 4high needs no RPM matching, that was only needed with Automatic Hubs

If front hubs were unlocked then front driveshaft would be at 0rpms so if you tried to shift into 4high while moving........grinding until chain and driveshaft match rear driveshaft RPM
Electric clutch engaged chain drive to spin it up to match RPM, kind of like a synchromesh "gear"

I did not know that and that’s really good info, thank you!!

 

[RonD]

Yes, electric clutch was only used with Auto Hubs and Electric shift transfer cases, so 2001 and up Ranger transfer cases didn't have it

Manual shift transfer case needed to have the front hubs locked, if there were manual hubs on it, there was even a sticker on the sun visor to that effect
But should be fairly obvious to most humans that if the front hubs are not locked then no 4WD in any case