Discussion on the Electronic Locking Axles

[JExpedition07]

I can’t fall asleep so this is what my mind is on tonight. Regarding the 3.31 & 3.73 Electronic Lock RR axles, does anyone have a diagram or pics of theirs opened up that shows how they work and the mechanics of it all? I see a plug goes into my rear differential housing, which I presume is some sort of solenoid that makes it switch to the locked mode. But I am curious what parts exactly that Ford changes from the standard open axle to the electronic locking units. I have read somewhere about a lock pin, but can’t find much more.

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[Buyer2021]

Known as "ELD" (electronic locking differential) in the workshop manual, here's two clipped excerpts for your reading enjoyment .....

The ELD system consists of the following components:​

• ELD field coil, located at the rear differential
• Rear differential with dog clutch
• ATCM (all terrain control module)
• TCCM (transfer case control module)
• MSS (mode select switch; unique for ELD equipped vehicles), located on the instrument panel

........

When the operator activates the ELD , the ELD icon displays in the IPC message center. If the vehicle is driven above the disengage speed, the IPC message center no longer displays the ELD icon, alerting the operator that the ELD is disengaged. Once the vehicle speed drops below the re-engage speed, the IPC message center displays the ELD icon again. If there is a malfunction with the ELD system, a CHECK LOCKING DIFFERENTIAL message is displayed in the IPC message center, letting the operator know the ELD is not engaged.​

​

Under certain conditions the ELD system has the ability to modulate powertrain torque output as well as system engagement/disengagement to protect internal ELD hardware.​

​

The ELD feature allows the ABS to override the engage state during special events. When this condition occurs the ELD icon flashes on and off rapidly.​

​

The differential locks when a PWM controlled magnetic field coil located inside the differential energizes. This locks the differential side gears and creates the locked differential.​

..........

The workshop manual has much more extensive discussion than just the above about the operation of the ELD system, including control logic flow diagrams and several tables of data.

Here's a couple of pics showing the ELD coil on the ring gear

Hope that helps with the insomnia

 

[parkerdog]

Remember the movie "Joe Dirt" the scene where the dad says "How exactly does the Posi-Trac rear end on a Plymouth work?" It just does.......

 

[408sbfmustang]

My truck didn’t come with the ELD. Would I be a good idea to have a posi unit installed?

 

[408sbfmustang]

I was thinking a Eaton Truetrac

 

[parkerdog]

I was thinking a Eaton Truetrac

coincidentally, I had one of those in a 408 stroker motor mustang. 4 eyed all the way! (83)

 

[JExpedition07]

Here we go guys

 

[JExpedition07]

a bit from the online owners manual, maximum speed table:

 

[JExpedition07]

I also appreciate the design of this little 4WD control setup. The fact you can control the drive modes, what 4WD mode you are in, and the rear locker engagement from this little area is efficient. Kudos to the design team on fitting all that functionality into this little dusty control for us .

 

[parkerdog]

And when your dog accidentally bounces off the dash and hits that button it really freaks you out until you figure out that the button is just stuck in.

 

[JExpedition07]

And when your dog accidentally bounces off the dash and hits that button it really freaks you out until you figure out that the button is just stuck in.

I could see that happening since it’s a momentary switch. I believe the old style you had to pull the knob out so hitting it wouldn’t cause engagement

 

[parkerdog]

I could see that happening since it’s a momentary switch. I believe the old style you had to pull the knob out so hitting it wouldn’t cause engagement

It didn't only engage it, it moved it in the mounting so that the button was stuck in and you couldn't tell until I started looking real close. The fix was sticking my fingernail in next to the button and popping it back into place. Then all was right with the world and I didn't have to go to the dealer for what I thought was going to be a big problem.

 

[Bryan Simon]

@parkerdog
And I’m guessing that pup did not even care one little bit.

I still think (I believe I recall ) she has that look
”so what are you gonna do about it? Going on

 

[parkerdog]

He wasn't happy. Bill is this one's name.

That's his "I'm ready to play bow" in my avatar. All you have to do is stomp your foot at a boxer and they are 0 to full play in seconds.

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