BW48-11 to 48-12 Swap

[pmb2024]

Hi everyone!

I drive a 2021 Ram 1500 (US spec, Built-to-Serve edition) based in the UAE. The truck came with the BW48-11 transfer case, which features a 4WD Auto mode. Around 60,000 km, I began receiving repeated 4WD Overheating warnings during desert trips. Eventually, the transfer case completely failed to engage 4WD, and I had to be recovered from deep in the desert since I couldn't self-recover in 2WD through soft sand due to the weight of the truck.

Diagnosis:
Visited two shops — both confirmed:

• Actuator is working
• Transfer case clutch is not engaging
• 4WD modes try to engage (as shows as 4wd engaged) but only rear wheels spin - regardless of 4H or 4L, or diff lock.

Through further research, I learned that part-time transfer cases tend to be more reliable for heavy off-road use — which fits my use case. I didn't want to part ways with my truck because of this and get a Rebel so eventually I came across examples of 4th-gen Ram owners swapping BW44-44 (4WD Auto) for BW44-45 (part-time) for this reason. When I checked my model, I found that my truck uses the BW48-11, and its part-time counterpart is the BW48-12. Mopar's official parts site confirmed this match, so I ordered a BW48-12 transfer case from the US, assuming the swap would be similar to the 4th-gen swap process.

• Current TC: BW 48-11 (Part #68250775AG)
• New TC: BW 48-12 (Part #68535808AA)

The Challenge
Once the new BW48-12 arrived, I took it to a local shop with experience working on Rams. They told me the transfer case’s electrical connector doesn’t match — the new BW48-12 uses a different plug and pin layout. From what I’d seen in the 4th gen swap, it’s common to re-pin or rewire the connector, so I expected that to be part of the process. However, the shop is unsure, saying that the wiring differences suggest the transfer case might function differently altogether and saying this is completely the wrong part. I’m not fully convinced and believe the issue might still be resolved with correct wiring — if we had the right diagrams.

In short:

• Did I really purchase the wrong transfer case, or is this just a wiring mismatch?
• If this is the correct part can anyone share wiring diagrams for:
  • BW 48-11 (Part #68250775AG) - I believe this has a 7-pin connector.
  • BW 48-12 (Part #68535808AA) - I believe this has a 6-pin connector.

I am thinking also about making a simple plug-in harness adaptor between the new TC and the truck so it's a cleaner solution than unpin, and easier for any shop to install.

TL;DR
I am trying to swap a faulty BW48-11 transfer case in my 2021 Ram (UAE-based) with a BW48-12 for better off-road reliability, but now facing wiring mismatch issues. Need help confirming compatibility and wiring diagrams to complete the swap.

 

[Marine6212]

Connectorexperts.com should have the parts you need to make a splice in harness.

 

[Bt10]

Does the auto style overheat in 4hi mode? I.e. not running the clutches often. Might simply replace and use locked in 4hi?

Sorry, no help on the wiring. Good luck. Tradesman is no 4auto also.

 

[kapinallinen2]

if we had the right diagrams.

Might have to re-program vehicle config?
Not sure if these help, wondering why one schematic has the 3 pin connector.
Apologies for the lack of resolution, they get compressed a lot when uploaded.

 

[pmb2024]

Connectorexperts.com should have the parts you need to make a splice in harness.

Thanks!
Any idea which connectors I need to look at? Or how to find out

 

[pmb2024]

Does the auto style overheat in 4hi mode? I.e. not running the clutches often. Might simply replace and use locked in 4hi?

Sorry, no help on the wiring. Good luck. Tradesman is no 4auto also.

Yes it was also overheating in 4h

 

[pmb2024]

Might have to re-program vehicle config?
Not sure if these help, wondering why one schematic has the 3 pin connector.
Apologies for the lack of resolution, they get compressed a lot when uploaded.

Thanks for this! There is an extra connector on the old TC, see photo. Could that be the 3 pin connector? I assumed it was a sensor required for the 4wd auto not needed/present in the new one.

Any chance you can send the DH8 schematic in better res? The other one is clear.

Edit: yest I believe it will need programming but I should be OK to do it in Alfaobd

 

[kapinallinen2]

Any chance you can send the DH8 schematic in better res? The other one is clear.

I`ll give it a try.

 

[pmb2024]

Hi all. I'm updating this thread in case it's useful to anyone in the future. After 3/4 trips to the local shop they managed to complete the swap to the BW48-12 I bought by replacing the electric actuator with one that was compatible with my Ram. The TC itself was mechanically compatible so this was a bolt on replacement. Everything seems to be working fine after a few months of use. For now I still have the original rotation button in place, but obviously the 4Auto button does nothing now. I may swap it in the future myself for one that does not have 4Auto for visual consistency.
In short if anyone is looking to do this in the future it is possible, but make sure you have the compatible part numbers and have a shop with sufficient knowledge of Rams to do this.

 

[damram]

Hi all. I'm updating this thread in case it's useful to anyone in the future. After 3/4 trips to the local shop they managed to complete the swap to the BW48-12 I bought by replacing the electric actuator with one that was compatible with my Ram. The TC itself was mechanically compatible so this was a bolt on replacement. Everything seems to be working fine after a few months of use. For now I still have the original rotation button in place, but obviously the 4Auto button does nothing now. I may swap it in the future myself for one that does not have 4Auto for visual consistency.
In short if anyone is looking to do this in the future it is possible, but make sure you have the compatible part numbers and have a shop with sufficient knowledge of Rams to do this.

I was looking into doing this swap a while ago. Went so far as buying the BW48-12 before I came across the same issue as you with the connecting pins (was planning to do the swap myself). I was thinking I would have to change out the whole wiring harness. I still have the BW48-12 in my shop, just been sitting there for about a year.
Do you have any information on the actuator that was swapped in? Maybe a part number?
If so, maybe I could actually get this swap completed. Thanks!

 

[Cesar592]

68535808AA) - Creo que este tiene un

I've wanted to do this for a long time, you know that's all that's needed.

 

[damram]

Man, this thread feels like a tease. Guy says he did the swap, but then doesn’t give enough pertinent information as to how. Then he ghosts everyone…

For the life of me, I can’t figure out what actuator he could have used that would plug into the harness and also bolt up to the transfer case. I went down a rabbit hole trying to search this, and I’m not entirely convinced it’s possible the way he described.

 

[ParriottsGarage]

Man, this thread feels like a tease. Guy says he did the swap, but then doesn’t give enough pertinent information as to how. Then he ghosts everyone…

For the life of me, I can’t figure out what actuator he could have used that would plug into the harness and also bolt up to the transfer case. I went down a rabbit hole trying to search this, and I’m not entirely convinced it’s possible the way he described.

New here, long time technician. Ventured down this rabbit hole recently on a 2022 Ram TRX. It appears the hardware is where the concerns really arise, mechanically the two cases are similar. electronically with the TRX and its drive modes converting hardware to part time 4x4 is proving to be difficult. Though this calibration is similar in other vehicles not specific to the TRX I can not comment on the subjective differences Stellantis has between the built in operating systems.
What the user above is stating is virtually impossible and there seems to be a clarity issue between him and the people actually working on the truck. Though you could physically wire the actuator to work the part time case is much different as far as encoder logic and positioning.
Most realistic path is:

1. Install the 48-12 and matching actuator/encoder.
2. Reconfigure the truck (if allowed) to a part-time 4WD system. ( Attempting to convert using Witech 2.0 will update when we make progress.)
3. Accept that the switch logic becomes 2HI/4HI/4LO, now “AUTO=2WD.”

This is the “OEM-consistent” approach.

_ I will update this post as we go through the challenges and hope to have a viable solution posted soon for other users to reference.

 

[Jimmy07]

Man, this thread feels like a tease. Guy says he did the swap, but then doesn’t give enough pertinent information as to how. Then he ghosts everyone…

For the life of me, I can’t figure out what actuator he could have used that would plug into the harness and also bolt up to the transfer case. I went down a rabbit hole trying to search this, and I’m not entirely convinced it’s possible the way he described.

Forget about supposedly swapping the actuator (not even sure how that’s possible).

To properly do the swap from the 48-11 to the 48-12, buy these parts for the new 8-way connector that plugs into the new transfer case:

1. Aptiv 13538370 connector (x1)
2. Aptiv 15430896 connector lock (x1)
3. Aptiv 15304719 female terminal (x8)
4. Aptiv 15366066 wire seal (x8)

Cut the wires off of your original 8-way connector that was plugged into the actuator.

Tape back the yellow wire with black stripe, and the yellow wire with light green stripe. Those two won’t be used anymore.

Slide the wire seals onto the other 6 wires, and crimp the female terminals onto them.

Insert the 6 wires into the new connector positions as follows:

• Brown wire into position A
• Yellow wire with dark blue stripe into position B
• Yellow wire with light blue stripe into position C
• Yellow wire with brown stripe into position D
• Yellow wire with gray stripe into position E
• Dark green wire with yellow stripe into position F

Now, cut the three wires off of the 3-way connector that was plugged into the original transfer case. Tape back the yellow wire with dark blue stripe, it won’t be used anymore.

Put the wire seals on the other two wires, and crimp the last two terminals onto those wires.

• Yellow wire with tan stripe insert into position G
• Yellow wire with dark green stripe insert into position H

Plug that connector into the new transfer case.

Go into alfaobd, and change VehConfig 3: T-Case Type to 44-45/44-46 w/Sync/44-48 w/Sync

 

[damram]

Forget about supposedly swapping the actuator (not even sure how that’s possible).

To properly do the swap from the 48-11 to the 48-12, buy these parts for the new 8-way connector that plugs into the new transfer case:

1. Aptiv 13538370 connector (x1)
2. Aptiv 15430896 connector lock (x1)
3. Aptiv 15304719 female terminal (x8)
4. Aptiv 15366066 wire seal (x8)

Cut the wires off of your original 8-way connector that was plugged into the actuator.

Tape back the yellow wire with black stripe, and the yellow wire with light green stripe. Those two won’t be used anymore.

Slide the wire seals onto the other 6 wires, and crimp the female terminals onto them.

Insert the 6 wires into the new connector positions as follows:

• Brown wire into position A
• Yellow wire with dark blue stripe into position B
• Yellow wire with light blue stripe into position C
• Yellow wire with brown stripe into position D
• Yellow wire with gray stripe into position E
• Dark green wire with yellow stripe into position F

Now, cut the three wires off of the 3-way connector that was plugged into the original transfer case. Tape back the yellow wire with dark blue stripe, it won’t be used anymore.

Put the wire seals on the other two wires, and crimp the last two terminals onto those wires.

• Yellow wire with tan stripe insert into position G
• Yellow wire with dark green stripe insert into position H

Plug that connector into the new transfer case.

Go into alfaobd, and change VehConfig 3: T-Case Type to 44-45/44-46 w/Sync/44-48 w/Sync

Holy Crap! Thank you!!! I’m going to look into this. This is by far the most helpful guide I’ve come across on how to get around the wiring! You’re awesome!