2013 5.7L 4WD Problems

My 2013 Tundra has been having 4WD problems. The truck is in 2WD, with the 4HI and 4LO lights blinking.

Originally I was told it was the transfer case actuator, and that to replace it I would have to split the transfer case. I had access to another transfer case, so I just swapped that on, but the problem did not go away.

At this point I figured it was the front ADD, and I replaced it (with a Dorman) and the problem persists.

Thanks to this forum I was able to track down the 4WD diagnosis pdf I have attached to this post.

I pulled the dash, and have tested the voltage at the 4WD control module (wish I had done this in the first place before swapping the transfer case) and I think the problem still lies in the ADD (paying the price for using Dorman over Toyota parts maybe) and was hoping someone might be able to chirp in and confirm. All of the voltages looked to be correct EXCEPT for DL2, which I believe should be reading under 1.5V, but was actually reading 13ish.

I believe this to be a sign that there is a problem in the ADD, specifically in that DL2 switch, but any help is appreciated.

Thanks a bunch!

 

Can you connect, don’t install, the old OEM ADD and take the same voltage measurement? Cuz if the new and old exhibit the same problem, then it could be the wire itself going to the ADD that might be bad.

In that diagram the DL2 switch is closed so it should read very little voltage. But if there is an open, either at the switch or somewhere along the wire, then you’ll see the 13 volts.

Use an ohm meter to test continuity of the wire

 

Unfortunately not, I don’t have the old ADD anymore, did the install a while ago and am only just getting around to attempting to fix it again now.

Thanks a bunch for the help!

So I should test the line from the plug from the 4WD module to the plug to the ADD for continuity? Just get some really long test leads?

 

Yeah you could test that. Just use some speaker wire to extend the leads.

 

Cruzer, thank you again, I found an open in a section between the 4WD control module and the ADD, I circled it in the attachment, also pulled the ADD and tested it, appears to be working correctly, flipping switches as needed.

If you don't mind one last fairly dumb question, is it possible to just pull that wire from either connector and replace it or do I need to order new wiring harnesses, or should I just go to someone who specializes in electrical?

The help has been greatly appreciated, cheers!!

 

It depends where the break is.
If the pin is no longer making good contact with the wire, then you'd need to pull the pin, get a new one and crimp it onto the wire. The tricky part will be finding a matching pin and removing it from the harness.
If the break is along the wire somewhere, then as long as you've got enough wire to connect new wire to bypass the break you can use any wire of similar gauge.

 

Hey Cruzer, just wanted to finally follow up. Thank you so much in your help tracking down the actual problem. I finally got around to replacing the section of wire that was open, and gave her a test, shes back to working perfectly. Crazy that the dealer and the specialist I saw immediately wanted to replace the transfer case actuator, followed by the ADD. Thanks again, your tip on chasing wires was the key to unlocking the problem and getting it fixed.

 

@ssr384 BTW where did you get that diagram with the voltage specs? Do you have one for when it's in 4Lo?

 

@Cruzer I found it here or on another Tundra forum on a thread asking about 4wd problem diagnosis. And yes it does have the readings for 4Hi and Lo. Hopefully I attached it correctly to this post, but this was super helpful in tracking down problems in the system as you can reference exactly which line(s) or switch(es) are not acting correctly.