4wd System Operation & Help Thread

Yea dealer techs aren't trained or paid to think outside the box, there are some that do but the majority just guess if it can't be found in the flow chart.
Good on you for finding the problem. This is the 3rd or 4th one I've seen, no one as of yet has found where the wire breaks though.

 

What is this mess inside the transfer case actuator? I'm getting a blinking 4lo light and noticed the vent line was cracked so I took a look inside. Seems like it came from the screw gear.

 

Just grease, they use it to lubricate the gears & contacts and keep them from corroding.
Normal for the grease to be there but it does look like you have some corrosion on the traces.

 

two questions, what does this circled symbol mean?


and which wires 3,5 or 6 have continuity to ground when 4wd is disengaged vs engaged?

 

The grey box indicates a Junction Box, the letters in the oval is the connector designation, and the numbers are the Pin numbers on the connector.
Connector PA is on the Instrument Panel Junction Box (J/B) No 2 which is located behind the glovebox to the left of the ECM, not that it is mounted upside down relative to the picture you will find in service info.

Follow the chart in post 1, 0v means the switch is Closed (Grounded).

So DL1 (Pin 6 Green) is closed in 2wd, DL2 (Pin 5 Pink/Blue) and ADD (Pin 3 Light Green/Black) are closed in 4wd.

 

thank you Dm93 for your quick reply, im dealing with this truck for awhile now, not using it much so no rush
here are my reading and it looks like major grounding problem.
Tested pin 18,19 and 7 on PA plug and all of them show 12 volts,
however when I grounded pin 18 my 4lo light disappeared but VSC light came on.
this 4wd problem went away last years when I changed alternator but came back soon after

 

That suggests you have the seemingly increasingly more common missing EE ground problem, thus far no one has found where the wire breaks but instead just bypassed it.
I have links to troubleshooting the first one we encountered in Post #2.

Bad ground on EE causing flashing 4wd lights, no cruise, & EVAP codes (See Posts 236, 237, 254, 257, 259, 272, 274, 275, & 278

 

i just did wire tracing and there was break at that firewall (marked yellow)
going from pin18 at PA connector toward EE and form EE to the cab, signal was lost at the firewall
recorded video as well but I first have to figure out how to post it here

 

Good job

That's interesting that it would break there, is it corrosion or a fatigue break?

Native video uploading isn't supported, you have to post videos on a video sharing site like youtube and then post a link here.

 

I would guess its fatigue, this part is not really working that much unless its jumping or vibrating

https://youtube.com/shorts/abvF-KCOhhE

https://youtube.com/shorts/v_h4x57cglg

 

Your not on the correct pin on the 1st video, that is Pin 11. Pin 18 is the 7th pin up in the right row, it is White/Black.

I've never had much luck with those circuit tracers but some people swear by them.

 

i based this on this post so I believe that this is correct pin
picture is upside down

 

In the video it's hard to tell which pin your in, it looks like the needle is in 10 or 11.

 

so when I ground pin 18 the VSC light comes on but 4lo disappears WTH? but with VSC light on all of the voltages are good except L4 which shows 0v instead of 12v , im lost again

 

Looks like you were in the 5 one down on the left. Which would be 18. Was it a white/black wire?


That black stripe on the yellow wire makes it look like it’s in that one. But it’s not. Looks like 18 to me?

 

Again, what color is the wire you are grounding?

 

Makes sense that the VSC light comes on with L4 at 0v because VSC is disabled in L4.

Unplug the L4 Detection Switch on the back of the Transfer Case Actuator and verify L4 goes to 12v with the ground bypass.

 

wire is black and white

 

Did as you said and L4 is still 0v with pin 18 grounded, however blinking 4wd and 4lo disappeared, took it for a drive and 4wd is not functional, just blinks when turned on, as soon as I plugged L4 back in actuator 4wd started blinking and VSC lit up

 

That's interesting, are you sure your on the right pin?

Transfer case isn't in L4 is it?