(Another) Manual Transfer Case Swap: 2003 FX4 L2 >> 2007 FX4 L2

[Jim_Philly]

Hi all -- there are a lot of threads here about swapping out an electric-shift BW1345 transfer case for the manual-shift version. I have an electrical/electronics-related question.

I have a 2003 FX4 L2 donor truck complete with all of the required mechanical parts in excellent shape (body rust, motor blown.. otherwise I'd just keep THAT truck). I would like to put the manual transfer case in my 2007 FX4 Level 2 with manual transmission. Physically, everything will bolt up just fine.

Unfortunately, starting with the 2006 model year, Ford implemented a high-speed CAN bus to connect all the modules together, including the PCM, 4x4 control module, and gauge cluster. This means that rather than point-to-point sensor/switch connections to multiple modules, everything goes back just to the "parent" module and then the modules talk to each other over the HS-CAN bus. (See attached diagrams).

The 2003 manual transfer case setup omitted the 4x4 control module entirely, and has a 4x4 position switch in the transfer case hard-wired to the 4x4 High/Low dash cluster lights and the PCM. The position switch either grounds out pin #1 or pin #2 depending on whether it's in high or low, and that satisfies the PCM and dash cluster.

Because the 2006-up Rangers didn't have a manual transfer case option, the CAN bus-based setup didn't account for that type of functionality.

Has anyone done a manual transfer case swap on a 2006-2011 Ranger? I have some ideas for workarounds but would love to hear from anyone that has already blazed this trail.

I'm thinking I will need to leave the 4x4 electronic selector switch in place, and switch it along with manually shifting the transfer case. I'm also thinking I'll need to somehow take the position encoder from an electronic shift motor assembly, and attach it (without the motor itself) to the manual transfer case so that it will communicate the transfer case position status back to the 4x4 control module and avoid any DTC's or malfunctions. But if there's a way to just make the 2-pin position switch satisfy the 2006-up electronics without the need for all that, I'd love to hear it.

Thanks! - Jim

 

[lowspeedpursuit]

I'm also thinking I'll need to somehow take the position encoder from an electronic shift motor assembly, and attach it (without the motor itself) to the manual transfer case so that it will communicate the transfer case position status...

A manual case doesn't have the rotary shift shaft that attaches to the motor, so you'd be building an interface from scratch.

This feels like a stupid question, but only '10-'11 had traction control, right? Do the computers actually do anything different in 4x4 except shift the case?

What happens if you use Forscan to tell the computers your truck's a 2wd, so it doesn't care the e-case parts are missing, and manually wire the indicator lights?

 

[Jim_Philly]

A manual case doesn't have the rotary shift shaft that attaches to the motor, so you'd be building an interface from scratch.

This feels like a stupid question, but only '10-'11 had traction control, right? Do the computers actually do anything different in 4x4 except shift the case?

What happens if you use Forscan to tell the computers your truck's a 2wd, so it doesn't care the e-case parts are missing, and manually wire the indicator lights?

As far as I know, my '07 doesn't have traction control (actually, I didn't know the '10-11 even had it). The Forscan programming is a good idea, I'll explore that. But the fact that even the older 2003 setup had a 4-Low status output direct to the PCM makes me think that the truck "needs" that piece of information for something else important (not just the dash indicator lights). I'm actually more concerned about that than I am about the lights - after all, a mechanical shifter tells you what position the case is in, don't really need the lights!

 

[Jim_Philly]

You know... If you can just slap one of those Behemoth Drivetrain manual shift conversion kits on an electric case, then I should be able to do what I described and just leave the motor harness unplugged, right?

 

[lowspeedpursuit]

Off the top of my head, the computer needs to know it's in 4-Low to correct the electronic speedometer and auto trans shift points. Per vaguely related googling, 4-Low may also disable cruise and ABS. Of those things, the speedo and cruise are arguably irrelevant, and you've got a manual, which just leaves ABS as a potential problem.

The Behemoth conversion is just a lever, control cable, and a box that converts push-pull to rotary control. You'd basically be building their box (a way to translate the push-pull of your shift lever) to a rotary position yourself.

It would arguably be easier to have a button tell an Arduino to spin a stepper motor, at which point you've circled back around to just leaving the entire shift motor plugged in but not connected to anything mechanically.

 

[Jim_Philly]

Off the top of my head, the computer needs to know it's in 4-Low to correct the electronic speedometer and auto trans shift points. Per vaguely related googling, 4-Low may also disable cruise and ABS. Of those things, the speedo and cruise are arguably irrelevant, and you've got a manual, which just leaves ABS as a potential problem.

The Behemoth conversion is just a lever, control cable, and a box that converts push-pull to rotary control. You'd basically be building their box (a way to translate the push-pull of your shift lever) to a rotary position yourself.

It would arguably be easier to have a button tell an Arduino to spin a stepper motor, at which point you've circled back around to just leaving the entire shift motor plugged in but not connected to anything mechanically.

I dug into the manual vs electric t-case diagrams to see if the manual shift cam and the electric shift shaft could co-exist and be frankenstein'ed together. Spoiler -- they cannot. So I've abandoned the rotary encoder option. I was just throwing the Behemoth module out there as an argument for the rest of the vehicle not 'caring' whether it's in 4WD or not, because the Behemoth setup provides no electrical provisions.

I'd like to simulate "stock" functionality, though, and I think I found my solution. I'll follow up when I wire this up and see if it works...

I dug into the "principles of operation" on the 2007 4x4 system and found the following (Incidentally, @lowspeedpursuit you're correct on the speedo):

The "4x4 Mode Switch" on the 2003 manual t-case grounds out either pin 1 or pin 2 depending on whether the transmission is in 4H or 4L. Those pins are an open circuit otherwise.

In the troubleshooting/diagnosis section for the instrument cluster lights, the following table is provided:

So if I take the 4H pin on the manual T-case switch and wire that to contact plate wires 2B and 3C, it will close (short to ground) in 4H and correspond to the 4x4 High mode switch position.

If I take the 4L pin on the manual T-case switch and wire that to contact plate wires 2B and 4D, it will close (short to ground) in 4L and correspond to the 4x4 Low mode switch position.

When it is in 2WD, both of the manual t-case switch pins will be open, satisfying the required 2B contact condition. My only remaining problem is showing 1A, 3C and 4D as "closed" - or shorted to ground - in 2WD mode. In theory, though, if the system is reading 2B as "open," then you'd think it would be programmed to know that it's not in 4H or 4L since that contact being closed is common to both. I suppose it may throw a DTC or the 4x4 lights may blink, interpreting it as a system malfunction. Only one way to find out! If that's the case, I may need to add some sort of circuit that senses an open 2B state and grounds the other three with a relay or something.

 

[gw33gp]

Off the top of my head, the computer needs to know it's in 4-Low to correct the electronic speedometer and auto trans shift points. Per vaguely related googling, 4-Low may also disable cruise and ABS. Of those things, the speedo and cruise are arguably irrelevant, and you've got a manual, which just leaves ABS as a potential problem.

I think the main reason the computer needs to know it is in 4WD low is, as you said, to correct the speedometer. I don't know about the ABS disabling. I know it doesn't disable in 4WD high. I pull the fuse for ABS when I hit dirt because ABS does some bad things off-road. I understand it is supposed to change the ABS strategy in 4WD, but it still doesn't help me. I never use cruise control off-road, so I can verify that either. I do look at the speedometer occasionally and it reads correctly in 4WD low.

 

[00t444e]

Unplug the shift motor and tape up the connector, none of the electronics are needed with a manual transfer case. You can splice into the wires to make your 4x4 light on the dash come on if you want to.

 

[fastpakr]

I think the main reason the computer needs to know it is in 4WD low is, as you said, to correct the speedometer. I don't know about the ABS disabling. I know it doesn't disable in 4WD high. I pull the fuse for ABS when I hit dirt because ABS does some bad things off-road. I understand it is supposed to change the ABS strategy in 4WD, but it still doesn't help me. I never use cruise control off-road, so I can verify that either. I do look at the speedometer occasionally and it reads correctly in 4WD low.

Isn't the computer interpreting speed from the rear axle? If so, it doesn't need transfer case status for that.

 

[gw33gp]

That may be true for some Rangers, but my 2002 Ranger has it some place in the transmission/transfer case area. I think it may be on the transmission output shaft in the transfer case adapter. I don't know what year that began but I believe all the later Rangers had that at least up to 2011.

 

[fastpakr]

Interesting. I thought the later ones all pulled vss from the rear axle tone ring.

 

[rubydist]

89-2000 got the speed signal from the rear axle differential.

2001 + got the speed signal from oss in the trans or transfer case.

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