4WD Issues

Hello friends,

Looked at the great DM93 info post about 4WD issues and finally got a multimeter and backprobes and I used the "expected" voltage chart and found:

In 4H I am not getting voltage to the TL1 (B25 pin) and DL1 (B13 pin).

In 4L I am not getting voltage to TL2 (B12 pin) or DL1 (B13 pin) but I am getting 11+ volts to the TL3 (B23 pin) and L4 (B17 pin) which are both expected to be zero in 4L.

Everything else is as expected.

About 14 months ago I posted asking for info about all this and had removed the front ADD and opened the cover.

I examined the two solder joints for the small electric motor and while they weren't visibly damaged or broken, I did resolder them, got new bolts for the cover and used neverseize on them so the front actuator is probably OK...maybe.

So...my question now is...

Should I attempt the same thing with the actuator on the transfer case? Take it off, open it up and see what's happening?

I listed the voltage issues in 4H & 4L, is there anything else that I should be checking for?

Thank you for any advice.

 

Should ask in that tread I would think,,,


@Dm93

 

So in 4H all the limit switches except TL1 and DL1 read correctly?
What about in 2H?

Not really concerned about the 4L readings because we need to be in 4H before it will go to 4L.

 

I prefer individual thread discussions on particular issues, it makes it easier to keep track of each one. When I get multiple people asking in the 4wd thread it get's hard to keep track of each persons chain of posts.

 

Appreciate you being around to help out!

 

Hello,

Thanks, yes everything is as expected in 2H
2 variances in 4H TL1 & DL 1

 

Can you verify those go to 12v with the ADD and Transfer Case Actuator unplugged?

 

Ummm okay, so I should unplug both actuators (front ADD and TC) and then Key On Engine Off and do a voltage test on both TL1 (B25 pin) and DL1 (B13 pin)?

 

I am new to threads, am I doing this right DM93?

 

Yes, this will verify the wires are not shorted to ground somewhere.

 

Well it probably would have been better to stay with your original thread instead of starting a new one but beyond that yea.
I was talking about I prefer people make their own thread for their 4wd problems instead of posting in the 4wd help thread otherwise it get's too unorganized.

 

OK I disconnected the 6pin electrical connectors to both and tested for voltage and yes, TL1 & DL1 both showed 11+ volts in 2H, 4H and 4L

 

So they aren't shorted to ground.
That's intersting that both the ADD and Transfer Case Actuator have a problem.

Did you have them both apart?
I'm wondering if maybe they aren't timed correctly.

 

I have not checked the TC actuator at all but last November I had the front ADD off but here is what happened...I sent it to a machine shop because one of the 5 cover bolts, the top right bolt seized and the head twisted off. The machinist said the whole thing fell apart when he took the cover off. I had never seen the inside prior.

We put it all back together and I checked everything, and resoldered the motor connections. I put 12v battery power to the ADD on two of the pins, probably from your prior post info, and had the thing actuating...or clicking anyways so it seemed like it was right. The shift fork did move side to side with battery power on the bench.

I plan on taking the TC actuator off in a few days and examining it like I did the ADD.

Am I on the right track here?

 

So it's possible the original problem is the Transfer Case Actuator and having the ADD apart it may be a tooth or 2 off so it's able to engage the axle but can't move quite far enough for DL1 to open.

These are just theories based on how the system works but without actually taking them apart and looking it's all I got.

 

Thanks for the info, B4 asking, I tried to immerse myself in your info-filled post about all the 4wd components, how they work in a linear format, what happens first, next, etc...fascinating stuff but I am in over my head but am following along...kinda.

So the voltages (or lack of) tells you that something is also likely wrong with the ADD?

RATS! I just commented to another post about how miserable the ADD was to remove compared to the one sitting on the TC.

OK, I will review your post about clocking the gears/getting the teeth right...I just can't remember what it looked like inside but I do remember thinking the front ADD gearing was a lot simpler than what I read about in the TC actuator.

B4 I got this truck, it was in a front end accident that apparently also damaged the AC system and the 4wd. The previous owner had her "brother in law" do the body repairs and he never even detected an issue with the AC or the 4WD so maybe a 45mph crash shook things up?

I will keep trying, thanks for your advice, time, patience and experience.

 

I tried to explain it there the best I could but the limit switches (TL1, TL2, TL3, DL1, & DL2) basically tell the ECU the position of the actuator, the detection switches (4WD, L4, & ADD) tell it the mechanical position of the Transfer Case and ADD.

I'm just going by the data assuming the tests are correct, with the ADD Actuator in order for ADD to close the shift fork has to physically move to the locked position so that tells me the ADD Actuator moved to the locked position but it either didn't move far enough for DL1 to open or something in the actuator is keeping DL1 shorted.

Same thing with the Transfer Case Actuator, 4WD closed so the Transfer Case has to mechanically be in 4wd but TL1 didn't open so the actuator either didn't move far enough or something is keeping TL1 shorted.

Did you verify the truck is indeed mechanically going into 4wd?

 

Oh man, I thought I hit post reply last night...

The part you wrote about limit switches versus detection switches helped me fill a gap in my understanding, thanks!

I have not verified mechanically that the vehicle "is going into 4wd", how would I do that? Lift the vehicle?

 

I mean it's usually pretty apparent if you drive and try to turn if it's locked in 4wd or not but yea jacking up the front end and trying to turn the front wheels & front driveshaft would tell you what is engaged.

 

I do recall putting the truck in 4H and felt the clunk and the turning was restricted so yes, mechanically yes but I will get out the jack stands this week and see what's what. Thanks again.