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Discussion Starter #1 (Edited)
I finally had time to work on a new ABS/VDC/TCS/EBD off switch mod and while I was only trying to get the ABS to turn off (the version 3 abs-off yaw sensor disable thread didn't work for me) the results ended up being worthy of a new thread. When everything was back together and I was testing the mod I found that if I turned the rocker switch on, the ABS/BRAKE/SLIP/VDC lights all came on and were disabled. I'm thinking ok great, that's what I wanted. But with the truck still running I flipped the rocker switch off and both the ABS and Brake lights turned off. I was like wait a second and flipped the switch back on, both the ABS/BRAKE lights turned on again. Then I flipped the switch off again and the ABS/BRAKE lights both turned off again. This mod gives you the ability to turn the Anti Lock Brakes and Electronic Brake Distribution on/off just by flipping a rocker switch, no truck restart required. I should also note that at least for now you will still have to restart to re-enable the VDC and TCS although I plan on getting rid of that requirement in a future update. For the mod you'll need:
  1. Rocker Switch
  2. Bosch style relay
  3. Primary wire
  4. electrical connectors
  5. Wire stripper
  6. Zip ties/splicing tape, etc.
Section 1: Systems Background Info

It helps to be familiar with the systems on the X so to start I'm going to talk about the different systems the X has and what they do so you'll have a reference guide for the terminology used and get a better idea of what what you're dealing with. The Xterra has multiple electronic driving aid systems, some trim levels may have additional systems like Hill Start (HSA) and Hill Descent Assist (HDC). But everyone should have Anti Lock Brakes (ABS), Electronic Brake Distribution (EBD), Traction Control (SLIP), and Vehicle Dynamic Control (VDC). Here's a look into what those systems do:

ABS
● The Anti-Lock Brake System detects wheel revolution while braking and improves handling stability during sudden braking by electrically preventing wheel lockup. Maneuverability is also improved for avoiding obstacles.
● If the electrical system malfunctions, the Fail-Safe function is activated, the ABS becomes inoperative and the ABS warning lamp turns on.
● The electrical system can be diagnosed using CONSULT-II.
● During ABS operation, the brake pedal may vibrate lightly and a mechanical noise may be heard. This is normal.
● Just after starting the vehicle, the brake pedal may vibrate or a motor operating noise may be heard from engine compartment. This is a normal status of operation check.
● Stopping distance may be longer than that of vehicles without ABS when vehicle drives on rough, gravel,or snow-covered (fresh, deep snow) roads.


EBD
● Electronic Brake Distribution is a function that detects subtle slippages between the front and rear wheels during braking, and it improves handling stability by electronically controlling the brake fluid pressure which results in reduced rear wheel slippage.
● If the electrical system malfunctions, the Fail-Safe function is activated, the EBD and ABS become inoperative, and the ABS warning lamp and brake warning lamp are turned on.
● The electrical system can be diagnosed using CONSULT-II.
● During EBD operation, the brake pedal may vibrate lightly and a mechanical noise may be heard. This is normal.
● Just after starting the vehicle, the brake pedal may vibrate or a motor operating noise may be heard from engine compartment. This is a normal status of operation check.


TCS
● Spinning of the drive wheels is detected by the ABS actuator and electric unit (control unit) using inputs from the wheel speed sensors. If wheel spin occurs, the drive wheel right and left brake fluid pressure control and engine fuel cut are activated while the throttle value is restricted to reduce the engine torque and decrease the amount of wheel spin. In addition, the throttle opening is controlled to achieve the optimum engine torque.
● Depending on road condition, the vehicle may have a sluggish feel. This is normal, because optimum traction has the highest priority during TCS operation.
● TCS may be activated during sudden vehicle acceleration, wide open throttle acceleration, sudden transmission shifts or when the vehicle is driven on a road with a varying surface friction coefficient.
● The SLIP indicator lamp flashes to inform the driver of TCS operation.


VDC
● In addition to the ABS/TCS function, the driver steering amount and brake operation amount are detected from the steering angle sensor and pressure sensors, and the vehicle's driving status (amount of understeering/over steering) is determined using inputs from the yaw rate sensor/side G sensor, wheel speed sensors, etc. and this information is used to improve vehicle stability by controlling the braking and engine torque application to the wheels.
● The SLIP indicator lamp flashes to inform the driver of VDC operation.
● During VDC operation, the vehicle body and brake pedal may vibrate lightly and a mechanical noise may be heard. This is normal.
● The ABS warning lamp, VDC OFF indicator lamp and SLIP indicator lamp may turn on when the vehicle is subject to strong shaking or large vibration, such as when the vehicle is on a turntable or a ship while the engine is running or on a steep slope. In this case, restart the engine on a normal road and if the ABS warning lamp, VDC OFF indicator lamp and SLIP indicator lamp turn off, there is no problem.


HDC
● The hill descent control system will help maintain vehicle speed when driving under 25-35 km/h (15-21 MPH) on steeper downhill grades. HDC will provide braking allowing the driver to concentrate on steering while reducing the burden of brake and accelerator operation.
● To operate the system, set the 4WD switch to 4H or 4 LO and push the HDC switch. The HDC indicator in the combination meter will turn on. While HDC is operating, the stop/tail lamps will illuminate.
● If the accelerator or brake pedal is depressed while the HDC system is on, the system will stop operating.
● During HDC operation, a mechanical noise may be heard. This is normal.


HSA
● The HSA system will assist the driver by applying the brake automatically and preventing the vehicle from rolling backward when starting on an uphill.
● The maximum holding time is 2 seconds. After 2 seconds, the vehicle will begin to roll back gradually and then HSA will stop operating completely.


Fail Safe Modes
There are two fail safe mode that can be activated. You can tell which one has been activated by the dash lights illuminated:
1. In case of an electrical malfunction with the ABS, the ABS warning lamp, VDC OFF indicator lamp and SLIP indicator lamp will turn on.
2. In case of an electrical malfunction with the EBD system, the BRAKE warning lamp, ABS warning lamp, VDC OFF indicator lamp and SLIP indicator lamp will turn on.

Once Fail-Safe Mode has been activated certain dash lights will illuminate. You can tell what has been disabled by what lights are on, for example if SLIP/VDC are illuminated that means traction control and stability control are off but the anti lock brakes and electronic brake distribution are still on. Here are the results of fail-safe mode on the different systems:

ABS/EBD Fail-Safe Modes
1. For ABS malfunction, only the EBD is operative and the condition of the vehicle is the same condition of vehicles without ABS/TCS/VDC system.
2. For EBD malfunction, the EBD and ABS become inoperative, and the condition of the vehicle is the same as the condition of vehicles without ABS/TCS/VDC or EBD system.

HDC/HSA Fail-Safe Modes
● In case of HDC system malfunction, the HDC indicator lamp will remain off even though the HDC switch is operated and the condition of the vehicle is the same as the condition of vehicles without HDC system.
● In case of HSA system malfunction, the VDC OFF and SLIP indicator lamps are turned on and the condition of the vehicle is the same as the condition of vehicles without HSA system.

VDC/TCS Fail-Safe Modes
In case of TCS/VDC system malfunction, the VDC OFF indicator lamp and SLIP indicator lamp are turned on and the condition of the vehicle is the same as the condition of vehicles without TCS/VDC system. In case of an electrical malfunction with the TCS/VDC system, the ABS control continues to operate normally without TCS/VDC control.


Section 2: System Layout

The way the system is set up the abs brain under the hood receives a variety of date from the wheels, steering, etc that it uses to make decisions. For the mod we need to disrupt that data flow to trick the system into a Fail-Safe mode. After reading through the FSM I decided to to focus on the brake signal input. The system can’t activate if it doesn’t know when the brakes are being applied and it seemed like one of the less complicated systems to mess with. Here are a few diagrams of the wiring layout and the harnesses on both the brake side and the abs brain side:



Section 3: The Mod

So now to the good stuff, the actual mod. I followed the instructions in the ABS off Version 3 mod for the configuration of my rocker switch. The switch has a 12v input, a ground, and a power out (the part of the switch that sends power). The power out runs to a single relay, here’s a couple sketches of my wiring setup. Disregard the notes about the Yaw sensor:


Just like in Phulld's version 3 mod this switch and relay combo is set up to disrupt the connection of a wire. With the switch off, the system functions normally, with it on the connection is broken, the abs brain senses something wrong and puts the system in fail-safe. However unlike in the version 3 mod we don’t touch the Yaw Sensor wiring and instead go straight to the abs brain.

Open the hood and locate the abs controller harness, it’s near the driver side firewall. The harness itself has one latch that has to be pulled to release the harness. Be careful with it the tracks get full of dirt and dust and don’t like to slide easily (at least on an 06). With that disconnected use a small pair of scissors or a knife to cut away at the wrapping on the wire bundle but make sure not to knick any of the wires.


Locate the sky blue wire with the silver dash marks. That’s the brakes ‘on’ input wire.



I made sure I had sufficient slack to attach connectors and then snipped the wire, reconnected the harness and turned the truck on to test. All of the right dash lights were on so went back and connected a wire to each end of the wire I cut. Then I ran those wires back through the firewall and to my relay. The wire end going into the abs brain goes on connector 87a and the end coming from the truck goes to connector 30. The way it works is you flip the rocker switch, it sends power to the relay and connector 30 is switched to connector 87. Given we don’t connect anything to 87 the signal becomes a dead end. Make sure you secure all of the wires you ran and re-wrap the abs wiring harness so you keep everything protected. I used some weatherproof splicing tape I bought at Ace Hardware:


And that’s it! Remember this mod is no restart required to re-enable the ABS and Brake Distribution but to reactivate the VDC/SLIP you will need to restart. I’m working that one out now, my goal is to get rid of the restart completely. Happy modding!

 

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Nice, I need to do this to my 2006 6m soon! Couldn't you just run the two wires you added to the blue with trace to a switch in the cab instead of a relay? Granted with a relay you only have to run one hot through the firewall to trip the relay, but then you need to have a relay...

I'm thinking you went more complicated in order to have a lighted switch for the abs.

I'd also recommend taking a spare female blade connector and connecting it to pin 87 of the relay so there's no chance it will ever ground out or even worse, rub through another wire in the harness and send voltage to something else and possibly fry something expensive!

What kind of mileage is on your 06? Mine is around 135k iirc. We have 4 road vehicles and 4 motorcycles between my wife and I so the truck doesn't get driven unless it's needed.
 

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Discussion Starter #5
Nice, I need to do this to my 2006 6m soon! Couldn't you just run the two wires you added to the blue with trace to a switch in the cab instead of a relay? Granted with a relay you only have to run one hot through the firewall to trip the relay, but then you need to have a relay...

I'm thinking you went more complicated in order to have a lighted switch for the abs.

I'd also recommend taking a spare female blade connector and connecting it to pin 87 of the relay so there's no chance it will ever ground out or even worse, rub through another wire in the harness and send voltage to something else and possibly fry something expensive!

What kind of mileage is on your 06? Mine is around 135k iirc. We have 4 road vehicles and 4 motorcycles between my wife and I so the truck doesn't get driven unless it's needed.
I configured the wiring this way because I wanted the rocker switch to be in the 'off' position when this mod isn't in use. Switching to 'on' means the mod is on and 'off' is off. Keeps it simple in terms of all the rocker switches functioning the same way.

You could configure it the way you describe if you're ok with the switch needing to be left in the 'on' position all the time and then being turned 'off' to activate the mod. Or if you wanted use a more basic switch like those on/off/on styles. The thing with this mod is you can't use a momentary switch because if the connection is restored the ABS will be re-enabled. Definitely protect terminal 87 if not using a relay harness you for sure don't want that contacting anything.

I had 153,000 miles on it when I did this mod and I'm at 173,000 now, the times that I've needed this mod it's worked great. Most recently was on a 120 mile beach adventure down Padre Island National Seashore.
 

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Yea most of my switches are plain black small ones not labeled on or off so I'd just orient it where up is on and down is off or something that feels intuitive to me. More than likely I'll use this https://www.radioshack.com/products/spdt-6a-paddle-sw?variant=20332076549 paddle switch and mount it in the cutout near the ebrake handle on the vertical side next to the cupholders. That way when I'm panicking and reaching for the ebrake I can just flip this switch and disable the Absurdly intrusive Braking System instead. That said I'll probably have down as ABS off so it's quicker to switch off in those moments of ice and snow and bad drivers.

Dealing with lighted switches requires extra thinking/planning/scheming to get everything to work like you want! Glad you figured it out and wrote this writeup!!
 

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Doing mine today.

There's actually TWO blue wires twisted with mating pink wires, looks like it's the blue with single silver dot and not the double dot one.. I just ran two wires through the grommet that the hood latch cable goes through.
124172


Update..
Well the abs light and slip light and 4x4 lights come on, the 4x4 indicator in the tach disappears. Reconnecting the wires through the switch shuts off the 4x4 light and the indicator appears in the tach but the abs and slip lights stay on unless I cycle the ignition quickly. I didn't try driving at all and just checked in the garage.

I have a 2006 Nissan Frontier 6 speed Nismo king cab if that makes any difference. Might try the other blue wire with two dots on it. Just have to pull the volant airbox again, maybe tomorrow.

Just went around the block.. apparently the blue one disables the speedo and resets the mpg and mph average meters on the dash lol. Though it does add a but of plausible deniability to getting pulled over for speeding....

Going to pull the airbox tomorrow and try the other blue wire I guess.

Update #2 Wire 41 definitely doesn't do anything on a 2006 Frontier 6M Nismo and abs still works (found a shaded dirt parking lot with ice still). Last night I actually did wire #11 and that had some effect on the truck warning lights and according to the service manual it's the wire that goes from the Unified Meter Control Unit to the ABS. It shut off the speedo and 4x4 info area and reset the MPG and MPH average meters in the dash. Apparently the xterra an frontier of the same age have the abs work in different ways.


Update #3 What does work but kills the speedo and 4x4 indicator (I can still shift from 2wd to 4wd, just not in or out of 4 Low) is the #4 wire "Ignition switch on or start" on the abs pump connector. No restart required!
 
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