4wd problem

[cbelisle]

To start off, I've been searching for a while, and can't seem to find anything to answer my specific symptoms.

I have a 07 v6 4R and recently when I switch it from 2hi to 4hi the 4wd light and yellow diff lock light flash indefinitely. I hear the ECU clicking. What is really weird, and the reason for this thread, is that the 4hi and diff lock engage (steering feels heavy, and a ton of resistance when trying to turn on pavement), but the flashing lights never go off. I've tried unplugging the 4wd ECU, and also tapping on the transfer case actuator, but none of those help. Any thoughts?

 

[ARunner]

Sounds like you have a frozen actuator in your transfer case. Unfortunately it's kind of common and even more unfortunately there isn't a simple fix, and it's expensive if you have to get a new actuator. I would recommend you try a fluid change in the transfer case to see if that loosens it up. It sounds like it's partially engaging which is why it feels like the center differential is in fact locking (it may be - just not engaged enough to keep the lights from blinking). This is the black plastic box that hangs off the back of your transfer case. Do some googling and you'll find lots of information about it. Mine recently started weeping some fluid, so although it works fine, I'll have to tear into it one of these days to replace the simple little o-ring.

 

[cbelisle]

So, I found the 4WD operation guide, and this chart helped me a lot.
Screen Shot 2018-06-19 at 10.21.21 PM by colin belisle, on Flickr
Since I feel the car engage 4H as well as the center diff lock, I believe my issue is in step 5/6. When switched from 2H to 4H, the center actuator switches to 4H AND the center diff locks. After that, a signal is sent to the front diff actuator (ADD), where it engages the axels, but it's NOT sending a signal back to the center diff actuator, resulting in the issue.

So, from this logic I pulled the ADD, and sure enough, it was full of water. The breather tube had cracked and wasn't even attached. I pulled it apart, cleaned it, soldered the motor terminals, and then tested it. It works when testing with a 12v battery, so I installed it and now just waiting on the sealant to set. I'll have an answer tomorrow evening if this has fixed the problem or not.
IMG_7632 by colin belisle, on Flickr
Yup, thats a puddle of water...
IMG_7634 by colin belisle, on Flickr

 

[cbelisle]

Ok, problem is fixed! I tried cleaning the old one, but the sliding contacts that are embedded in the plastic case were corroded and falling apart. I got a whole new unit, and now the system works like new!

 

[alvarog]

To start off, I've been searching for a while, and can't seem to find anything to answer my specific symptoms.

I have a 07 v6 4R and recently when I switch it from 2hi to 4hi the 4wd light and yellow diff lock light flash indefinitely. I hear the ECU clicking. What is really weird, and the reason for this thread, is that the 4hi and diff lock engage (steering feels heavy, and a ton of resistance when trying to turn on pavement), but the flashing lights never go off. I've tried unplugging the 4wd ECU, and also tapping on the transfer case actuator, but none of those help. Any thoughts?

I'm having the exact same issue. I can hear the transfer case actuator engaging and the front axle/driveshaft as well but the diff lock and 4wd lights will not turn off. I'll try your solution with hopes for similar outcome.

do you know if removing the screws for the front ADD plate will leak oil from the differential?

 

[cbelisle]

I'm having the exact same issue. I can hear the transfer case actuator engaging and the front axle/driveshaft as well but the diff lock and 4wd lights will not turn off. I'll try your solution with hopes for similar outcome.

do you know if removing the screws for the front ADD plate will leak oil from the differential?

I don't believe any oil leaked out, but it was a while ago and can't quite remember. the screws are a PITA to get too. good luck!