E-Lock locked in 2WD, 4HI & 4LO

Austin · 05-24-2005, 06:43 PM

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 [b] 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.

milleniamarv · 05-24-2005, 07:27 PM

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".

Austin · 05-24-2005, 07:47 PM

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?

docopharm · 05-24-2005, 07:50 PM

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

**Kronos1965** · 05-24-2005, 07:54 PM

Austin,

Outstanding job with the detail!

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

Great job again.

Mike

HavockWK · 05-24-2005, 07:58 PM

I wish I had a locker on my 4x2 OR. Dang Nissan!

Austin · 05-24-2005, 08:16 PM

Quote:

Originally Posted by Kronos1965

Austin,

Outstanding job with the detail!

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.

SmoKedOuTtiTan · 05-24-2005, 09:17 PM

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

Burly · 05-24-2005, 10:37 PM

Macgyver!!!

*95wolverine* · 05-25-2005, 04:53 AM

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.

honeykeeper · 05-25-2005, 05:36 AM

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

Highland Beer

05nismo · 05-25-2005, 07:10 AM

Quote:

Originally Posted by Austin

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.

Austin · 05-25-2005, 09:02 AM

Quote:

Originally Posted by 95wolverine

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...

Quote:

Originally Posted by 95wolverine

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:

Quote:

Originally Posted by 95wolverine

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.

Titan4x4Aggie · 05-25-2005, 09:17 AM

stupid 11/03 build date

i get no e-lock on my 4x4 offroad

Austin · 05-25-2005, 09:24 AM

Quote:

Originally Posted by honeykeeper

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.