4WD won't go into 4H

I bought the truck used and I noticed that sometimes it would go into 4lo but never 4hi.

The 4wd light always flickers on the dash.

I’ve been trying to diagnose the 4wd issue for months but to no avail.

I inspected the bottom, and noticed on the transfer case motor that there were 5 wires instead of the 6 I normally see in pictures. What does the missing wire do?
This picture was taken from the right side of the truck facing the left.Any help would be much appreciated.

 

If you're not stranded and needing immediate assistance, you can remove the "help" from your title.

With that said, 4Hi and 4Lo work independently in that, 4Lo changes the speed at which your transfer case is in. This is done by means of a mechanical lever, and only when the vehicle is in Neutral.

For 4Hi, all this does is tell your actuator to engage the front CV axles so your front wheels receive power.

Seems like the issue is your actuator may need more troubleshooting. There are a few threads on how to send power and test it.

 

Sorry about that, next time I’ll avoid doing that.

Just so we’re on the same page, 4hi is the one that engages the front while 4lo just changes the speed of the transfer case?

Some additional details:

now when I go to engage 4lo I’m not hearing or feeling a buzzing like I’m used to, and there is certainly no locking of the driveline like before.

Should I open the transfer case actuator and give it a clean?

 

Assuming you haven't gotten anywhere with your issue? I'll try to help here but going to need some more info.

Do you have an automatic or manual transmission and which transfer case do you have? J-shift transfer case or 2-4 button transfer case? You are right that in either wiring diagram I look at, it has 6 wires. It's hard to tell the wire colors from your picture so I'm not sure what's missing on yours.

If you have the button, you could try tapping the actuator on the back of the transfer case. I've seen that actuator get stuck occasionally and not send a signal to the front diff to engage the front driveline.

That is correct.

 

It’s a 5 speed manual with the push button system.

Thank you for your help.

 

Ah, Ok...I was assuming your picture was of the actuator on the back of the front diff (re-reading your first post, you even say transfer case. That's my bad). The 2-4 select motor should only have 5 wires going to it as seen in the picture below.

If you push the 2-4 button and can still spin your front driveshaft, then I would think the actuator on the back of the transfer case is stuck. Check the 4wd fuse before pulling the actuator off lol

 

Thank you for your time, I’ll be sure to check the fuse then pull apart the actuator (If needed).

 

No problem! You could also jump the 2 leads on the DETECTION SW on your transfer case actuator to see if the front diff actuator moves. It should be above the connector in your first post. That would be an easy test to determine where the problem starts/stops.

I hope you are able to get the transfer case actuator working (if that's the issue but I'm willing to bet it is)! Keep us updated.

 

Thanks for the info. I’ll be sure to update you if I make any progress.

 

@Baja Devil - it seems like you missed what @Malek said about clicking the 4Hi selector button and then determining if you can still spin the front driveshaft by hand or not.

The 4wd systems in these trucks work in a specific sequence and your diagnosis should work through that sequence in the same order of operations in order to determine where the failure is occuring.

Here's a rough overview of that sequence:

1. Transfer case actuator engages front drive shaft after 4Hi selector is pressed.
2. Transfer position indicator switch (the one in the T-case) detects transfer case is in 4WD and sends signal to 4WD ECU.
3. 4WD ECU then sends signal to front diff (ADD) actuator to engage CV axles.
4. Transfer position indicator switch (the one on the front diff) detects that the ADD actuator has engaged 4WD, and sends a signal to the 4WD ECU.
5. The 4WD ECU then illuminates the 4WD dash light to confirm to the driver that 4WD is engaged.

I'd suggest working though this list in this order to rule in/out possible causes. Otherwise you're just guessing and this problem could continue to stump you.

 

I personally had a stuck actuator as the previous owner didn’t change the fluids enough and didn’t use 4wd often, they can freeze as well so be thinking about that in cold weather. Tapping on mine freed it up and now I just shift into 4hi every month or so and move only in a straight line. Helps keep everything moving

edit.. I do have a J transfer case though. May be different

 

Currently the front drive shaft dosen’t spin even with the button clicked in.

 

To my knowledge the 4wd was hardly used by the previous owner and I’m unsure of the fluid changes.