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This is a revisit and updated version, with new pics, of the original “E-Lock in 2WD, 4HI and 4LO” mod done back in 2005. Credit for discovery, initial write-up and execution of this mod goes to Austin, and can be found HERE in his original thread. Thanks goes to him for making this possible for us all.
Due to the # of people who seemed to be having issues or were hesitant to attempt it on the ’08-present models, and the lack of recent photos, I decided I’d give it a shot on my 2010. After one failed attempt due to a crossed wire and blown fuse, and then it acting weird on me, I was able to get it to function as desired. If you have basic mechanical and electrical skills you should have no trouble accomplishing this. Just be patient and take your time. I tried to be as clear as possible, but if you are unsure of something just ask.
DISCLAIMER: By doing this, you are assuming all responsibility and/or liability for any damage that could result due to your work or driving practices after completion, as well as any issues that may arise with warranty work should you break something and they find this done. Not all service dept's are ok with us doing stuff like this
List of items you will or may need to do this:
• DPDT relay (Radio Shack PN: 275-218)
• Various wire connections. (I used bullet connectors. Get at least 8 pairs)
• Wire Taps (unless you choose to strip and solder those connections)
• Spade terminals (8, 3/16” females for the relay terminals, and whatever you need for your switch)
• Heat Shrink Tubing (if you want it)
• Test light (to verify 12v switched source if you want)
• Multi-Meter (good to have for any electrical work and for checking continuity, voltage, etc…)
• Wire (I used 16g)
• Wire cutters/crimpers/strippers
• Whatever you need to remove any paneling or seats if needed
• SPST (on/off) Toggle switch, unless you choose to use factory switch; see the update below for this
Terms:
DPDT: Double Pole Double Throw
DLCU: Differential Lock Control Unit
DLS: Differential Lock Solenoid
NOTE: I am not sure how the VDC, ABLS and ABS functions on older models, but on my 2010, when I flip my switch in 2WD, the “VDC OFF” light comes on along with the “DIFF LOCK” light.
UPDATE: This can now be accomplished using the factory diff lock switch to activate the mod. CLICK HERE to learn how. If you choose to do it this way, leave out the wires that would go to the toggle switch and follow the directions in the link.
After reading everything in the original thread along with comparing new and old wiring diagrams and schematics, it appeared that the function was the same, and things didn’t look different from an electrical standpoint. I started by locating the DLCU and verifying that the wire colors and terminal locations were still the same, which they are. The DLCU on my 2010 PRO-4X CC is located on the back of the cab under the carpeting behind the passenger side seat as shown in the photo below. It may differ between CC and KC or even trim level, but my guess is it will be behind the seat somewhere. It will have a big “D” on it just as the one in the original thread appears to.
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From here, I located the wires needed based off their location on the connector. The picture below is looking at the plug from the side the wires go in (the “Harness Side”, or HS, is how the service manual refers to it).
![]()
The next diagram is how the terminals are numbered looking from the Harness Side and I have colored the terminals you need, based off the color of the wire coming out of them. These are the wires we need to locate in the kick panel.
NOTE: You can do all the wiring for the relay back here behind the seat if you wish. This will eliminate all worries about choosing the correct wires from the bundle up front. All you will need to run to the front is 2 wires to your switch. The actual wiring directions are the same regardless of where you place your relay, so long as you use the correct wires. If you choose to do it back here, just follow the steps for cutting and tapping wires as described later on.
DLCU Connector (looking from harness side)
![]()
Next, I traced the wires from the back up to the kick panel using a multi-meter. There is several of each color mixed in the wire loom running down the truck, so you need to be sure to remember which ones you choose.
The next photo shows the location of the wires you will need almost exactly as they were in the loom. The blue wire was the only one I moved to get a picture of. The Black, Yellow and Purple wires all pass through the connector in the white box and then up and to the left in this photo. So you can verify the correct wires by making sure they go there as well. The blue wire goes up towards the firewall with some others.
![]()
Next is a shot of the wires separated from the rest.
The blue wire is a shade darker than the other blue wires and they are all just a bit bigger (16g vs 18g).
The blue is an ignition-switched +12v source.
The black is a ground
The yellow is a switched 12v from the DLCU
The purple is a switched ground from the DLCU.
![]()
Due to the # of people who seemed to be having issues or were hesitant to attempt it on the ’08-present models, and the lack of recent photos, I decided I’d give it a shot on my 2010. After one failed attempt due to a crossed wire and blown fuse, and then it acting weird on me, I was able to get it to function as desired. If you have basic mechanical and electrical skills you should have no trouble accomplishing this. Just be patient and take your time. I tried to be as clear as possible, but if you are unsure of something just ask.
DISCLAIMER: By doing this, you are assuming all responsibility and/or liability for any damage that could result due to your work or driving practices after completion, as well as any issues that may arise with warranty work should you break something and they find this done. Not all service dept's are ok with us doing stuff like this
List of items you will or may need to do this:
• DPDT relay (Radio Shack PN: 275-218)
• Various wire connections. (I used bullet connectors. Get at least 8 pairs)
• Wire Taps (unless you choose to strip and solder those connections)
• Spade terminals (8, 3/16” females for the relay terminals, and whatever you need for your switch)
• Heat Shrink Tubing (if you want it)
• Test light (to verify 12v switched source if you want)
• Multi-Meter (good to have for any electrical work and for checking continuity, voltage, etc…)
• Wire (I used 16g)
• Wire cutters/crimpers/strippers
• Whatever you need to remove any paneling or seats if needed
• SPST (on/off) Toggle switch, unless you choose to use factory switch; see the update below for this
Terms:
DPDT: Double Pole Double Throw
DLCU: Differential Lock Control Unit
DLS: Differential Lock Solenoid
NOTE: I am not sure how the VDC, ABLS and ABS functions on older models, but on my 2010, when I flip my switch in 2WD, the “VDC OFF” light comes on along with the “DIFF LOCK” light.
UPDATE: This can now be accomplished using the factory diff lock switch to activate the mod. CLICK HERE to learn how. If you choose to do it this way, leave out the wires that would go to the toggle switch and follow the directions in the link.
After reading everything in the original thread along with comparing new and old wiring diagrams and schematics, it appeared that the function was the same, and things didn’t look different from an electrical standpoint. I started by locating the DLCU and verifying that the wire colors and terminal locations were still the same, which they are. The DLCU on my 2010 PRO-4X CC is located on the back of the cab under the carpeting behind the passenger side seat as shown in the photo below. It may differ between CC and KC or even trim level, but my guess is it will be behind the seat somewhere. It will have a big “D” on it just as the one in the original thread appears to.
From here, I located the wires needed based off their location on the connector. The picture below is looking at the plug from the side the wires go in (the “Harness Side”, or HS, is how the service manual refers to it).
The next diagram is how the terminals are numbered looking from the Harness Side and I have colored the terminals you need, based off the color of the wire coming out of them. These are the wires we need to locate in the kick panel.
NOTE: You can do all the wiring for the relay back here behind the seat if you wish. This will eliminate all worries about choosing the correct wires from the bundle up front. All you will need to run to the front is 2 wires to your switch. The actual wiring directions are the same regardless of where you place your relay, so long as you use the correct wires. If you choose to do it back here, just follow the steps for cutting and tapping wires as described later on.
DLCU Connector (looking from harness side)
Next, I traced the wires from the back up to the kick panel using a multi-meter. There is several of each color mixed in the wire loom running down the truck, so you need to be sure to remember which ones you choose.
The next photo shows the location of the wires you will need almost exactly as they were in the loom. The blue wire was the only one I moved to get a picture of. The Black, Yellow and Purple wires all pass through the connector in the white box and then up and to the left in this photo. So you can verify the correct wires by making sure they go there as well. The blue wire goes up towards the firewall with some others.
Next is a shot of the wires separated from the rest.
The blue wire is a shade darker than the other blue wires and they are all just a bit bigger (16g vs 18g).
The blue is an ignition-switched +12v source.
The black is a ground
The yellow is a switched 12v from the DLCU
The purple is a switched ground from the DLCU.
Great job!!!!!
