4wd System Operation & Help Thread

Hey guys i have the dreaded blinking 4w/4lo every once in a while.

I can get it to locked into 4 wheel,but disengaging back into 2 wheel is a little difficult.

i hear the click behind glove box locking into 4 wheel, but when i turn switch to 2 wheel it sounds like a buzzing over and over and it wont go back into 2 wheel, until i drive forward/reverse, eventually itll go into 2 wheel.
The buzzing continues as it tries to switch from 4W to 2W.

Is there a relay behind the glove box?
I havent had a chance to pull in apart, plus wiring isnt my forte.
Maybe my switch is bad?
Any thoughts?

 

The relays are built into the 4wd ECU (location in the first post of this thread), the fact one of them is buzzing when shifting to 2wd kind of suggests to me there may be a cracked solder joint on the circuit board.
You may want to pull the 4wd ECU out, take the cover off of it, and examine the circuit board for burned spots or cracks in solder joints.

 

Ok i can handle that, thanks for the suggestion and advice!
Ill get back when i get to it,and update.
Thanks again

 

Just want to highlight / clarify that point right there. You really should be moving down the road in a mostly straight line for the 2Hi <> 4Hi switch. Thats the best way to reduce any driveline bind and let the actuators do their job moving the components inside the t-case and ADD. Im not saying that is your problem, "buzzing" sounds are certainly abnormal, but every little bit helps if you're in a pinch

Into / out of 4Lo is where you need to be under 2mph or else the truck will beep at you.

 

Yes i guess im horrible at explaining
Always in motion
My problem is going back into 2w
In motion
Just wouldnt release until forward/ backward.
It 4 wheel season here and i have to try and figure this out, but time isnt on my side.

 

Like I said since you have a relay buzzing sound only when going from 4wd to 2wd and not when going from 2wd to 4wd I'd want to examine the circuit board of the 4wd ECU for cracked solder joints or damaged components, if nothing is found there then there's some other checks we can do.

 

Thanks i appreciate it!
Hopefully i can dig into it this weekend.

 

Ok so i pulled the ECU but im not sure how to check the board it almost look like it slides in the casing. I tried pulling
t slightly but no give,
There are no seams in the casing to pop it open.
i

 

Usually there's a screw or plastic clips that hold those types of modules together.

 

If there are i dont see them. It looks like it slides in on 2 slot type runners.
The only removable part is the cover around the plugs.

 

I'm not 100% sure, most of those type modules come apart pretty easy.
I don't have time to go pull mine apart and see at the moment.

 

Thats cool
i plugged it back in for the time being.

 

Just took mine apart, the board just slides in. A bit of a tight fit but it does come out relatively easy.

 

Awesome
Thats what i thought it looked like, i tried pulling on it, i didnt move.
I didnt want to jack it up.
I guess ill pull a little harder
Ill let you know what i find
Thanks again

 

Yea it takes a bit of wiggling but it does come out.

 

Ok finally got back to this.
It seems im gonna move slowly on this, anyway got the board out.
I see nothing out of order (not that i know much about circuit boards) buuut no burn marks or loose solder that i see. I inspected the plugs going into board..
I also pulled my switch that looks fine too.
When you have a chance lmk what you think i should check next..
Like i said no rush

 

Just ran into a 4hi/4lo issue.
Just replaced the transfer case actuator motor/housing, and 3 months ago replaced the ADD.
Tested it out after install, 4hi engaged/disengaged like it's supposed to... when I clicked to 4lo i got the dredded flashing. Can hear the ecu clicking on acc and battery power, but it would not disengage 4wd.
Only thing I can think now is an electrical issue

I'll have to get under tomorrow and manually switch it to 2wd for the time being from the transfer case, but definitely need to get this fixed.

Any help is appreciated where to start.

 

Srry I forgot about your post yesterday, your symptoms are difinitely unique.
I'm trying to think of how/what to test.
I think I would want to put a test light across both the ADD and Transfer Case motor circuits and see what I get when the buzzing occurs.

 

I'm thinking either the Transfer Case Actuator is out of time or we have a circuit problem.
You could start with the limit switch voltage checks outlined in the first post or checking the Actuator timing.

 

No biggie
Ok
First off i guess i need a test light
Should i buy a multimeter while im at it?

Im pretty good at mechanical stuff when it explained.
Electrical is a whole new ball game.
If you can walk me through this id appreciate it.
Is that something i test at the ecu plugs?
Thanks again