How-To: OEM Locker Bypass and install custom OTRATTW Switch


Shut up Baby, I know it!
Denver Adjacent
I'm sure a lot of people are familiar with the first half of this mod. Bypassing the locker relay. For those that are not familiar, the purpose of bypassing the relay is so the locker can be engaged in any drive mode at any speed. That being said, if you drive faster than about 10mph on pavement and turn the locker on, bad things could happen.

I've taken it a step further than just the bypass by also replacing the OE locker switch with a custom Carling switch from OTRATTW. I'll cover the whole thing step by step. This is for O/R and Pro4x equipped trucks only. If you don't have the factory locker, this writeup will do you no good. Also, this was done on my 07. Wiring will be the same for all other years but the wire colors may not. So just be aware you should pay more attention to the pinout of the plugs than the color of the wires.

Tools / materials required:
Phillips Screwdriver
10mm socket and long extension
Wire cutters / strippers / crimpers
crimp connectors
3 red tap splices
Female spade connectors (preferably insulated)

Time required: About 45 minutes

First off, here's the switch:

Standard single pole single throw switch. Lower LED (text area) independent for connection with the dash illumination, upper LED dependent to be on when the switch is activated.

Here is a link to the exact switch I'm using. These are available in a variety of different color combinations from OTR. If you don't see something on the website you want, call and ask. They can build damn near anything.

There's four sections of the wiring schematic from the factory service manual that we will be referencing. For anyone that has downloaded the manual from Niccoclub, these diagrams are on pages RFD-83 and RFD-84.

The first is the pinout of the locker control module:

The 2nd and 3rd are what the wires actually do on the module:


And the final one is the pinout for the switch that's in the dash:

We'll start by removing the lower trim under the steering wheel. Pull the screw next to the center console and under the trim closest to the door. The panel should just pop off. Remove the plugs for the mirror controls (and any other switches you may have there) and set that panel aside. Under the panel if you look just to the left of the steering column, you'll see two 10mm/phillips bolts holding the module in.

I found it easier to get the wiring harness out by unbolting the module.

Once you've got it unplugged, set it aside and cut the tape off the wires so you can see what you're working with.


There's 8 wires we're concerned with here.

Pin 1 - Green/White - Keyed Power
Pin 3 - Black - Ground
Pin 9 - Yellow - Power from locker switch ON
Pin 11 - Gray - Low side locker solenoid
Pin 12 - Blue - High side locker solenoid
Pin 20 - Brown - Power to Diff Lock Position switch (on axle)
Pin 21 - Sky Blue - Power from Diff Lock light in dash
Pin 22 - Green - Power from locker switch OFF

Reference this, to figure out what pins are what:

All other wires remain unaltered.

Pins 9, 11, 12, 20, & 21 can be cut off flush with the connector. Do NOT cut pin 1, or 3. And cut pin 22 about 2-3" up from the connector.

First thing we're going to do is attach pin 11 to pin 3. So using a tap splice crimp the vehicle end of the gray wire onto the black ground wire. This gives the locker solenoid a constant ground.

Next we're going to attach the vehicle side of 9 & 12 together. This passes the 12v from the dash switch directly to the locker solenoid:

And then 20 & 21 together. This takes the power from the dash light and makes it wait for a ground from the sensor switch in the axle. When the locker is successfully engaged, ground will be applied to the circuit making the dash light come on:

Then we take the connector side of 22 that you left long and use a tap splice to connect it to pin 1 for keyed power. This makes sure that the relay has power whenever the vehicle is on.

NOTE: IF YOU ARE NOT REPLACING THE SWITCH WITH A CARLING SWITCH AND ARE JUST LEAVING THE OE LOCKER SWITCH IN PLAY STOP HERE. Going further alters the wires so that the factory switch will not work. You can plug the module back in, reassemble the dash and test.

For those interested in replacing the switch, read on.
From there I used the 3rd tap splice to attach the vehicle side of pin 22 to the black wire also. So the green wire that goes to the switch is now a ground:

That's it. You can now plug your locker relay back in and re mount it under the dash.

Lets move to the center stack.

You can reach in behind the center stack and push the stock locker switch out and disconnect it. And then promptly throw it in the garbage.

Cut all the wires off flush with the connector.

Strip all the wires back and crimp insulated female spades to all 5 wires.

That wiring layout is as follows:

Green - Upper LED ground
Yellow - Power to locker relay
Green/White - Keyed Power
Brown - Illumination Ground
Red - Illumination Hot

Using the OTR wiring schematic, connect the Red and Brown to pins 6 and 7 respectively on the switch. The green wire goes to Pin 8, the yellow to pin 3, and the green/white to pin 2. As pictured here.


You're done. Pop the switch back into the dash, re-assemble the trim under the steering wheel, and test it out.


You'll notice that the indicator on the switch tells you when the switch is on and power is being applied to the locker, but the dash light tells you when the locker is actually engaged. I like it this way as it's kind of a two step verification on functionality.

Here's a few night shots you can really see the illumination. First is just with the dash illumination. And yes, it dims with everything else.


Next is what it looks like when the switch is on.


Enjoy your anytime locker!
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Titan Swapped / SAS'd
Founding Member
Huntsville, AL
I need to do the second part of this mod so bad.

This mod has gotten me out of a tight spot, too. When my 4WD went out the first time, my locker saved me from getting winched into several trees.


Test Drive
How does e-locker work? Is it a brake blockade? Is the rear differential locked mechanically?

Wysłane z mojego SM-N910C przy użyciu Tapatalka


Bought an X
Just a helpful hint idk if it matters but I would disconnect the battery or be very careful doing this I did this to my 09 frontier and accidentally touched two wires together and blew the diff lock controller which caused a can code and the abs and slip lights to be on. I know the steering angle sensor and g sensor have to be reset after the battery is disconnected so that is something to consider. Just don't want anybody else to have to pay $120 for a used controller ($350 for a new one) like I did lol


Total Tease
Supporting Member
Covington, Va
Ok. First things first, take it all back apart, read through the instructions again while looking at the harness and make sure that what you have done matches the instructions.

Don't take for granted you did anything right the first time. Especially the crimp splices. They occasionally don't make contact.


Test Drive
Gilbert Arizona
Plz help did this mod on my navara d40 spain built 2009 diesel. It works but abs dont work and abs light on

1 - Check the ground wire (white one). Make sure you have the splice on the correct side. Go over the wiring diagram again, you have a wire crossed.

2- unplug ground to battery to reset ECU.

3 - clear the codes

Hope it helps.


Test Drive
so did this mod and it works as expected, but I made a little slip up,

last step on pin 22 and pin 1, I was a little confused on the instructions and accidentally cut the pin 22 too close to the connector and only connect the wire side to pin 1, was I suppose to connect both sides on the cut pin 22 to pin 1?

it still works, it's just the VDC off, slip, and ABS lights are on if I do need to do both sides sounds like I will need a terminal release tool and to re do terminal 22.


Shut up Baby, I know it!
Denver Adjacent
Yeah. You have to power 22 with the keyed power. That's why your vdc and slip lights are on. In its current state, the BCM can't see the module. Hence the error.


Test Drive
so I connected 22 (from connector) to 1, and same issue slip & ABS lights still on,

any other ideas?

things I tried,
1. verified connection with the tappers)
2. disconnected battery to reset ECU
3. checked diff lock module fuse (maybe I should check ABS fuses?)

could I have fried the module like the above poster


Test Drive
Issue fixed! and this works like a charm.

since I see some folks above who had a similar issue as me and neither followed up, I am sure as more people try this mod they will run into the same issue.

this is how I fixed it:
the issue comes up if you wire any of the wiring wrong, or you start your car without the connector plugged in (TRY BELOW BEFORE BUYING A NEW DIFF CONTROLLER) :

you will need a scan tool, I used a 100$ Bluetooth one that can read SRS/SAS/ABS codes.

the following codes will pop up on your OBD2 scanner C1187, U1000, C1163 (see below)

basically from what I read in the service manual U1000 means there is an error in the CAN data network, and the other hint is C1187 which is diff lock controller error. so BCM cannot communicate with the diff lock controller, and won't do so until the errors are cleared. clear these codes.

now when you clear the codes the lights will go out for 5 seconds, then will come back on if you hit the diff lock button, or wait.

now that the U1000 code is cleared and it can communicate with the diff lock controller you will be able to retrieve ABS error codes from the diff lock controller so re-scan again and you should get a new error code
code P1838, now you need to clear this code again.


once cleared the lights will go out and on until you restart the car and all should be good.

TL;DR: the fix is to clear the code, wait 10 seconds then clear the codes again, you need to do this twice, then shut off and on the car and they should be cleared.

hope this helps someone.


Test Drive
YOO!! New member, second time owner, I found this page from a youtube page. So, from reading, we can "convert" the rear diff from factory to a locking diff?? I have a 4WD X, I can lock my rear diff with this bypass??


Bastard Admin from Hell
The _actual_ Off Road and Pro4X trims (used car sellers will often incorrectly identify trucks as such) had factory locking diffs. This mod is to bypass the factory logic and engage the locker at your command instead of when the computer thinks its ok.


Shut up Baby, I know it!
Denver Adjacent
YOO!! New member, second time owner, I found this page from a youtube page. So, from reading, we can "convert" the rear diff from factory to a locking diff?? I have a 4WD X, I can lock my rear diff with this bypass??
Negative. As Deeb said, this bypasses the factory logic on the stock locker system. So you have to have the Pro4X or Off-road model for this to function.


Test Drive
First thing I would say about this mod is do not listen to the very first instruction that says to cut wires flush with the connector. Cut the wires at least an inch back from the connector, in the case that you accidentally cut the wrong wire you will still have a way to splice the wires back together.