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Discussion Starter · #1 ·
It works!

I've modified the wiring to the Diff Lock Control Unit - now my rear e-locker will lock up in 2WD, 4HI and 4LO. I used a DPDT relay and a lit rocker switch controlling the relay to switch both power and ground.

When I flip my rocker switch in 2WD, 4HI or 4LO, I get a lit DIFF LOCK light on the instrument cluster, and nothing else. So, I can have a locked rear diff and keep ABLS to the front wheels.

I verified the diff is actually locked by putting the truck up on jackstands, locking the rear diff in 2WD, shifting to Neutral and spinning one rear tire - the other tire spins the same direction. (An open differential would cause the tire to spin the opposite direction.)

I also verified the diff is actually locked by playing in the dirt. In 2WD with the diff locked, I lay down two beautiful marks with no SLIP light. While turning, the inside rear tire slips - it's obvious the diff is locked.

I'm still able to lock the rear diff in 4LO using the OEM switch.

I used a separate rocker switch (instead of using the OEM switch) and a DPDT relay so that the installation wouldn't cause any malfunction lamps, blinking no-worky lamps, or other unintended results.




First - a failed attempt:

I tried to simulate the transfer case in 4LO by grounding out the 4LO switch. Here's a bit of info about that:

The 4LO switch is a normally open switch, and it closes when the transfer gear is under 4LO condition, detected by the L-H shift fork position. The 4LO switch is located on the transfer case, just inside of the front prop shaft flange. The 4LO switch inputs to the Transfer Control Unit.

I jumped across the 4LO switch, and across the 4LO and the Wait Detection Switch. All it'll do is confuse the Transfer Control Unit. The problem is that the 4WD Shift Switch inputs to the Transfer Control Unit, which then compares it to the various sensors on the transfer case.

With the 4WD Shift Switch in 2WD or 4HI, when you jump the 4LO switch (pin 24 to ground) you'll get a flashing 4LO light - indicating a faulty 4LO switch or faulty wiring to the 4LO Switch.

With the 4WD Shift Switch in 2WD, when you jump the 4LO switch (pin 24 to ground) and the Wait Detection Switch (pin 17 to ground), the 4WD Shift Indicator Lamp (the little drivetrain picture that tells you if you're 2x4 or 4x4) will go out and the 4WD Warning Lamp (the lamp that says 4WD) will flash.

The problem is that the 4WD Shift Switch inputs to the Transfer Control Unit, which then compares it to the various sensors on the transfer case. When the 4WD Shift Switch position isn't consistent with the position sensors on the t-case, you get blinking lights and no-worky.




Having failed at tricking the control units into thinking conditions are met to lock the rear diff, I bypassed the control units entirely – I wired 12volt power directly to the diff lock solenoid.

Here a picture where all the stuff is:


Here are a couple wiring diagrams:




Here’s a pin explanation:


+12volts is applied on terminal 12, with terminal 11 being switched ground – power to the diff solenoid is controlled by switching the ground at terminal 11. I’m betting the diff control unit can isolate the +12volts on terminal 12, so I wanted to switch both power and ground.

Here's how I wired it:

The quick’n’dirty:
Cut the [Y] yellow wire at terminal 12 at the diff lock control unit harness.
Cut the [V] violet wire at terminal 11 at the diff lock control unit harness.
Strip insulation from black wire at terminal 3 at the diff lock control unit harness.
Strip insulation from [R/B] royal blue wire at terminal 1 at the diff lock control unit harness.

Connect DLCU side of yellow wire to relay terminal 1.
Connect jumper from royal blue wire (power) to relay terminal 3.
Connect diff lock solenoid side of yellow wire to relay terminal 5 (diff lock solenoid terminal 4).

Connect DLCU side of violet wire to relay terminal 2.
Connect jumper from black (ground) wire to relay terminal 4.
Connect solenoid side of violet wire to relay terminal 6 (diff lock solenoid terminal 2).

Connect jumper from royal blue wire (power) to hot side of rocker switch.
Connect jumper from black wire (ground) to other side of rocker switch.
Connect jumper from load terminal on rocker switch to relay terminal 7.
Connect jumper from relay terminal 8 to black wire (ground).





I'll post some pics of the install in a bit.
 

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Thanks for a very informative post! :) :) And this is from someone who doesn't have an elocker, just VDC but always happy to learn more about the Titan and its possibilities.

Only hope that others making the mod play nice with their "new toy".
 

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Discussion Starter · #3 ·
The Diff Lock Control Unit is positioned right between the two rear seats - so, if you want access to it, you need to remove both rear seats. There is no need to do this, though - there is an easier place to do the wiring.




Here's the harness connector at the Diff Lock Control Unit. Note the two blue wires on terminals 1 & 2 of the connector (upper right). The manual labels them as color "R/B" which must mean royal blue. Remember that blue color.




The best place to do the wiring is in the driver's kick panel. There is only one wiring loom which runs to the rear of the truck. There is also a nice place to house the relay - inside the white plastic housing, right next to the little brown connector. Good'n'protected.




Note the two smaller blue wires you can see in this photo - they are not the ones you want to cut. If you see two colors of blue, go with the darker blue. Royal blue vs. sky blue.




When you pull the tape off that loom, locate the yellow, violet, black and royal blue wires. They're all a bit larger than most of the other wires - 16 awg vs 18 awg. Separate them from the rest and follow the wiring diagram in the first post above.




Here's the truck on jackstands to verify the diff is locked. Okay, okay, so I got lazy... two jackstands and the jack under the back pumpkin.




Here's where I mounted the lit rocker switch.





Anybody need more/different pictures?
 

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Outstanding! Great post, I'm gonna want to do this myself eventually. :clap: :clap:
 

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E-Lock

Austin,

Outstanding job with the detail! :bump:

I do want one more picture though...
Show me the twin strips of rubber pullleaaaase!

Great job again.

Mike
 

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Discussion Starter · #7 ·
Kronos1965 said:
Austin,

Outstanding job with the detail! :bump:

I do want one more picture though...
Show me the twin strips of rubber pullleaaaase!

Great job again.

Mike
Thanks!

I'll have to go out again tomorrow and get a picture for you. :D
 

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Good info man. This is what Titantalk.com is all about. Trying new things.
 

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Macgyver!!!
 

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Well Done Son. As an engineer, I appreciate your thoroughness and detail. You should also be proud of the fact that you are (I believe) the first to accomplish this.

Just a thoght for ya.. How about using the factory Diff Lock Switch? Seems that the one that sould be in the center console area is now pretty much worthless or at best, a parallel setup. Just something to consider.

Again, well done.

PS.. A photo of the relay you chose for this application would be appreciated.
 

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Great job and pics.!!!!

Great job Austin...congratulations on your success......now can you disable the ABLS next?!!!
Peace-Tom :cheers: Highland Beer :rockon :cheers:
 

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Austin said:
It works!

I've modified the wiring to the Diff Lock Control Unit - now my rear e-locker will lock up in 2WD, 4HI and 4LO. I used a DPDT relay and a lit rocker switch controlling the relay to switch both power and ground.

When I flip my rocker switch in 2WD, 4HI or 4LO, I get a lit DIFF LOCK light on the instrument cluster, and nothing else. So, I can have a locked rear diff and keep ABLS to the front wheels.
Is this a titan only thing? Can you verify this? On my frontier, the ABLS works even in 4LO with the rear locker on. I verified this when I was stuck in the mud. I was in 4 LO, rear locker on, and when I would hit the gas pedal, the slip light would blink, and I could feel the front brakes hitting on either side.

Very informative post, I plan to do this to my frontier, hoefully, this is very similar to your instructions. Thanks.
 

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Discussion Starter · #13 ·
95wolverine said:
Well Done Son. As an engineer, I appreciate your thoroughness and detail. You should also be proud of the fact that you are (I believe) the first to accomplish this.
Thanks! I'm at least the first geek on TitanTalk to do this...


95wolverine said:
Just a thoght for ya.. How about using the factory Diff Lock Switch? Seems that the one that sould be in the center console area is now pretty much worthless or at best, a parallel setup. Just something to consider.
The Diff Lock Mode Switch inputs to the Diff Lock Control Unit - both switch lock and switch unlock have a DLCU input. I didn't specifically try with the Diff Lock Mode Switch, but with other switches I've disconnected (like the 4WD selector switch), malfunction lamps have resulted. So, I didn't want to isolate the switch from the control unit.

For necessary systems, I always use soldered connections.

The Diff Lock system isn't necessary for car control - the entire Diff Lock Control Unit, the solenoid & all the associated wiring could open, short or just vanish, and the only consequence would be a malfunction lamp and non-locking rear diff. Because this isn't a necessary system, I used crimped, insulated spade disconnects - so, I'm able to completely remove everything and return the wiring to stock in about 5 minutes.

The disconnect terminals I used look like this:



95wolverine said:
PS.. A photo of the relay you chose for this application would be appreciated.
Sure, I can do that. It's Radio Shack p/n 275-218. DPTP relay, 12VDC/10A. The Diff Lock Control Unit is fused upstream by a 10A fuse (as you saw in the first wiring diagram in the first post), so a 10A relay is large enough. I wanted a DPDT relay to maintain the circuit in the original orientation when not in use, for two reasons. 1, all the control units check all their switches and sensors regularly, communicating via lan/can. If I'd isolated the diff lock solenoid from the DLCU, there'd be a malfunction lamp. 2, both ground and power are routed through the DLCU, so I'm betting it's able to isolate both, meaning I needed to supply both ground and power for a complete circuit.

 

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Discussion Starter · #15 ·
honeykeeper said:
Great job Austin...congratulations on your success......now can you disable the ABLS next?!!!
ABLS is integral with ABS - they're both controlled by the ABS control unit. So, to disable ABLS, just pull the ABS fuse.

Why would you want to disable ABLS? It may not be the best limited slip in the world, but from a traction standpoint it's quite a bit better than an open diff. From a maintenance stanpoint, it's quite a bit better than any LSD or locker.
 

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Discussion Starter · #16 ·
05nismo said:
Is this a titan only thing? Can you verify this? On my frontier, the ABLS works even in 4LO with the rear locker on. I verified this when I was stuck in the mud. I was in 4 LO, rear locker on, and when I would hit the gas pedal, the slip light would blink, and I could feel the front brakes hitting on either side.
When in 4LO on an Titan, when you toggle the OEM diff lock control switch to lock the diff, you also get an ABS light on the instrument cluster. The ABS light lindicates a malfunction with the ABS system (in this case, the ABS system has been deenergized).

If the ABS and BRAKE lights come on, it indicates a further failure with EBD - Electronic Brake Distribution.

For verification... I've been on quite a few mud trips with friends. Nice thick sloppy muck, deep enough to stop a built truck with a ton of lift and 40" tires (but open diffs...). I've been stuck quite a few times also - where you have ample time to see which wheels are/aren't spinning. I've done alot of those mud runs in 4LO with the diff locked. I've been videotaped quite a few times also.

I've never seen the SLIP light come on when in 4LO (SLIP light indicates ABLS activation). When I've been stuck in the mud in 4LO, I've asked and been told that one of my front tires isn't spinning. Also, I've seen my truck on video after - one front wheel tossin' a rooster tail while the other one has fallen asleep. Is that verification enough?

The great thing now is that I can be locked and keep ABLS to the front.


But... I would love to look at the manuals for your Fronty. I'm an information whore... Do you have a set on CD you could lend me?



05nismo said:
Very informative post, I plan to do this to my frontier, hoefully, this is very similar to your instructions. Thanks.
If you have manuals, I'll go though and verify this on your fronty.
 

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Ok, now isn't there a reason they made it only usable in 4WL?

I thought I read somewhere that using the locker at speed while turning could destroy it?

Just thought I would ask before I do this myself.
 

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Justintoxicated said:
Ok, now isn't there a reason they made it only usable in 4WL?

I thought I read somewhere that using the locker at speed while turning could destroy it?

Just thought I would ask before I do this myself.
It can be used responsibly in any choice of driveline. Leaving it on all the time when on or off road would not be good, but when there is no traction, the wheels will be slipping enough to not damage the locker.
 

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I was thinking that you could use it in the sand? I mean, if I could only turn it on when there was no traction I would already be stuck and then I might was well put it in 4W Low anyways?

Also how are you going to keep ABLS to the front in 4WD? I thoguht you said it was disable din 4WL? Why would Nissan Disable ABLS in 4WL and not in 4WH? Since 4WL is mostly to get you out of being stuck already? That would mean you should use 4WH if your stuck?

Sorry if these are dumb questions this just is not makeing sense to me.

Also, I probably should know but I dont, How do you wire a relay to work with the switch? Did you have to fuse the switch to drop the power? and if not why not just use the switch with no relay?
 

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Discussion Starter · #20 ·
Justintoxicated said:
I was thinking that you could use it in the sand? I mean, if I could only turn it on when there was no traction I would already be stuck and then I might was well put it in 4W Low anyways?
Especially with a solid axle, you can easily get into a situation where one wheel is stuffed up into the fender well and the other wheel is spinning in free air. With an open differential, all the power goes to the free spinning wheel - the wheel with the least traction, or the wheel that is the easiest to turn. Open differentials distribute equal amounts of torque to both sides - so, if one side has no resistance, no torque can be generated, and zero (equal) torque is distributed to both wheels.

ABLS is great because it gives that free spinning wheel something to push against, so that torque is able to be generated and distributed to the wheel that actually has traction. But, ABLS isn't the be all/end all in traction devices...

With a locked diff, both wheels spin equally and at the same rate. So, if either wheel has adequate traction, neither wheel will spin.

There are places that a prerunner (a 2WD truck with a locked rear diff) can go that a normal 4x4 (with both open diffs) can't.

It's not that you "can only turn it on when there is no traction" - but you don't want to have a locked diff in situations where you have great traction. On pavement, you don't want a locked diff. When you turn, the inside wheel must travel the same distance as the outside wheel - so the tire slips. That's fine if you're in the dirt or sand, but you can experience much increase tire wear if you do that on pavement. Or, worse, your tires don't slip and you break some drivetrain component.

A locker also comes in very handy in situations where you don't want to spin your wheels, such as going up a steep incline. With a locked diff, you can keep a nice steady, easy pace - there's no need to hit it running.



Justintoxicated said:
Also how are you going to keep ABLS to the front in 4WD? I thoguht you said it was disable din 4WL? Why would Nissan Disable ABLS in 4WL and not in 4WH? Since 4WL is mostly to get you out of being stuck already? That would mean you should use 4WH if your stuck?
ABLS is married to ABS - you can't have ABLS without ABS. ABS and ABLS are still enabled in 4HI and 4LO, but, if in 4LO with the diff locked (by the OEM switch), ABS & ABLS are deenergized. Since my way is bypassing the control units completely, ABS and ABLS remain energized even if the diff is locked - so you keep ABLS for the front end.

4LO isn't made to get you unstuck if you get stuck in 4HI. Different types of terrain require different gearing. For rock crawling, you want to go nice and slow - so 4LO is likely appropriate. For trail use, depending on how open the trail is, 4HI is likely appropriate. For pulling stumps (or hooking up to mighty Ford Explorer 6cyl's) or any situation where you need maximum torque to the ground, 4LO is appropriate. For snowy highway travel, 4HI is likely appropriate - but you definitely don't want a locked diff in that situation.



Justintoxicated said:
Also, I probably should know but I dont, How do you wire a relay to work with the switch? Did you have to fuse the switch to drop the power? and if not why not just use the switch with no relay?
All relays have a coil (an inductor) which, when energized, will close at least one set of contacts to complete another circuit. The relay coil is energized (controlled) by the switch. 12VDC is applied to one terminal of the switch, then run a wire from the other terminal of the switch to one side of the relay coil (terminal 7 or 8), then run another wire from the other relay coil termina to ground. Flipping the switch completes the circuit, which energizes the relay coil, which operates the contacts. For a DPDT relay, two circuits are broken and two circuits are completed when the relay is energized.

It's a good way to isolate the control side from the load side - you don't have full load current running through the switch. In this case, I used a 30A switch - so, it definitely would have been able to handle it, but I would've had to use four switches to accomplish the same function of the one relay that I used.

I'm a bit confuzzled by your question: "Did you have to fuse the switch to drop the power? " Can you ask it a different way?
 
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