Yep, another 4wd thread...with a twist

[Gix1k4]

First, let me say great site. Have been a member at TV for about a year now, but just joined up here.

Ok, on to the dilemma.

My g/f bought a 2007 TB LT 4.2 last year. The previous owner told us that it "just needs the actuator on the front for the 4wd to work". I used to work in the auto repair trade, so I wasn't too concerned about doing the work. Long story short, I bought an actuator and installed it. No change.

I also noticed the battery light was dimly lit whenever the truck was running. In the process of troubleshooting that problem, I found that the previous owner had disassembled the cluster and removed the LED for the Service 4wd light. (I love unscrupulous people)

After much head scratching and trips to the wrecking yard for an Encoder motor, 2005 TCCM, 4wd switch and an ignition switch, I pulled the transfer case and disassembled it to find shrapnel inside from the clutch pack. I got a low mile, used transfer case and installed it. Everything was great....for awhile.

A few weeks ago the g/f mentioned that it seemed like her TB was all over the place in the snow. I drove it and discovered that, again the 4wd was not working. I jacked it up and followed the flow chart on the thread and figured that the axle disconnect was the problem. Back to the wreckers where I removed 2 disconnects for $125, I broke the first one, and successfully got the 2nd one off. I didn't just swap them, I ordered a new fork, bearings and seals and rebuilt it from the 2 I had.

I reinstalled it yesterday, with no change, still no 4wd. However, I can use a long screwdriver to engage the axle, but I have to push on the fork really hard, harder than I think the actuator is able to. Are Dorman actuators known to be weak, or are they generally good units?

Having no 4wd service light is certainly a pain in diagnosing the problem. But a $400 cluster is hard to swallow. I thought it might be too much grease in the disconnect, and that maybe a long drive to move it around might help. Went for a drive and on the way back I engaged 4hi, it didn't make any sounds at all. The light on the switch went to 4hi and stayed there, even when I selected 2wd.

I drove home and pulled the #8 fuse for 5 minutes. After doing that it reset back to 2wd. I got in and turned the key to accessory and selected 4hi, I heard the encoder motor shift, and the actuator whine, but then all the lights went out on the switch. Turned key off and back on and selected 2wd and it returned to 2wd.

I'm at the end of my rope with this thing..... As soon as it is functioning again it will be for sale and out of my hair. My family used to buy only GM, but after the last 4 of them, we have been going with Ford. After my electrical nightmare 97 sierra, I went to an F250, and am now on my 3rd one with no serious issues. My mother owns a 07 Malibu that, at 47000kms had problems with the electric steering, which GM said was a "bad alignment" causing the hard steering in one direction and super easy the other direction. They refused to fix it under her extended warranty, even after it was diagnosed as the steering column by a 3rd party shop.....End rant.

 

[IllogicTC]

I would have gone right back to the seller with a steel-toed boot after discovering the system has been tampered with to lie to you about 4x4 status.

The actuator's a pretty small motor but has a LOT of gear reduction to compensate. When you rebuilt the unit what kind of grease did you use? I think there's some Mobil brand grease the guys around here are fairly fond of, I believe it's red stuff.

On to the actuator. Please excuse me if this writing seems a little "watered-down" for the casual shadetree mechanic, I originally wrote it elsewhere and figured it may be of some use to you, too. Here goes:

This post by The Roadie could help you understand what's supposed to be going on up front a bit better.

There's 4 wires to the actuator - +12v, Ground, Reference, and feedback. The actuator actually receives its own power supply instead of requiring juice from the TCCM - the TCCM just tells it what to do.

First up is the brown wire on the FAD (front axle disconnect) harness, in position "D" on the connector. It's your +12v. Ensure that you're receiving voltage at this wire. Fuse #48 on the rear fuse block feeds it - if it's good, inspect all wiring leading out to the FA as well as you can. This is going to sound really stupid, but here's how the wiring runs. The power first goes to the back to go to its fuse (this part of the system shouldn't be considered if everything else is functioning). Then it runs all the way back up to the underhood fuse block. From there, it goes on its path to the FAD. The wire is brown the entire time from the rear fuse block onward.

Next is your ground, this one's easy to spot. It's on position B on the connector, and is obviously black. Ensure that there is a proper ground. This includes checking the wire itself, and physically checking the ground. The wire runs back from the FAD to the underhood fuse block, and from there utilizes the ground on the lower-left side of the engine (along with some other components such as the SAIS and a bunch of the lights, etc.) It comes out of the fuse block as pin F3 on connector C1, and goes to the grounding point. Clean and reseat the ground as a precaution if you feel like it, I don't see what it would hurt.

Next is position A, a light-blue wire that's the actual sending wire from the TCCM. Inspect the length of it for any damage as well as you can, it runs from pin A2 on connector C1 from the TCCM straight to the FAD. If it's grounding out anywhere, this is an obvious indicator that it's not going to work. The signal should be driven low when the command is for retraction, and high for the command to extend. If you're getting low voltage from the wire when it's supposed to be in 2HI, it could be shorting out somewhere.

Last is your Position C wire, it's the black one with a white stripe. This is your feedback wire that tells the TCCM where the actuator's at. When the FAD is retracted (2HI), the voltage should be low. When the FAD is extended, the voltage should be high. It runs from Position C on the FAD connector, to the underhood fuse block where it enters at pin D6 on connector C3. It exits at pin E11 on connector C1 to go back to the TCCM. At the TCCM, it goes in pin B6 on connector C2. Inspect the length of this wire as best as you can.

Please note that if the service 4x4 lamp is already on, the system has already "given up" and will not likely try to run the actuator again. It's supposed to "reset" with a cycle of the ignition switch but who knows? Also, if you had the service 4x4 lamp before changing the actuator and did not reset the lamp, it may still refuse to attempt engagement. It may be possible that you'll have to disconnect your battery for a few minutes to reset the system to test the reference voltages. Follow best procedure for testing +12v and ground circuits, the +12 seems a bit long to do a simple continuity test (could always use a length of wire to aid) but you may be able to stretch test leads just far enough to test continuity for the ground.

I'm not sure what the voltages for references should be at, but if it's anything like other references it would be between 0-5v for both, with high being at or close to 5 and low being at or close to 0.

I hope this helps, if not at least you've gotten a very good explanation on how it's wired up.

 

[IllogicTC]

Also, welcome to the site, you were smart to start an account over here, TV's former 4x4 smart-guy (the roadie) migrated over here years ago so this is the place to figure your issue out

 

[Gix1k4]

Thanks for the response, I'll try and touch on the points you mentioned.

-I did go back looking for the seller, but he had moved by the time I realized that he had tampered with the cluster.... Buyer beware I guess....

-Fuse #48 is good

- It's funny you mention Mobil grease. Mobil SHC220 red synthetic is all I use... For my boat and vehicles, as well as my snowplow lube points. I find it doesn't dry up or "wash" away. And it is what we use on our pillow blocks and motor bearings where I work, so I get it at cost. It is great stuff, I work in a 24/7 manufacturing facility. Downtime is something we don't like.

-Grounds, all ground points were cleaned and dielectric grease applied when I was trying to diagnose the battery light issue about 8 months ago. I found a ground diagram online and followed it.

I will look farther into the wiring this week, right now I need to step back and take a breather before I get too frustrated to think straight. I think I'm going to have to bite the bullet and replace the cluster to be able to chase this properly, as well as I won't sell my problems to anyone else. When It goes to a new owner it will be fully functioning.

Thanks again.

 

[C-ya]

Could you not just replace the missing LED or light on the dash rather than replace it? There are threads here that go into that. I have a couple of bulbs out here and there that I'll be tackling when the weather warms up.

 

[Gix1k4]

Could you not just replace the missing LED or light on the dash rather than replace it? There are threads here that go into that. I have a couple of bulbs out here and there that I'll be tackling when the weather warms up.

I thought about going that route, but I don't think my hands are steady enough to solder that tiny LED on. They are the small, flat, square style.

I have read a lot about the magic viscous coupling, but from what I can tell this truck doesn't have it. The only thing inside the T-case is a clutch pack similar to what is in any automatic transmission I've ever been into. The spring and what I would call a pressure plate ate themselves up in the old transfer case, I wonder if the wrecker unit I installed did the same thing?

The truck was at a local Mister Transmission for 2 days and they weren't able to solidly pin point the issue. They also have an '03 TB with similar issues there. They tried 2 other encoder motors, and used their scanner to watch what the system is doing, and according to them, the computer thinks it is doing what it should, but mechanically it isn't able to engage the t case and/or front diff. They want it back next week to do more on it. They said that they did have 4wd at a couple times (on the hoist), but it is sporadic.

 

[IllogicTC]

Sounds like a chewed clutch pack to me, intermittently grabs. But I'm not the expert, I'm just going off info gleaned from literally dozens of 4x4 threads Kind of curious if, assuming someone has the time and patience, it's cheaper to re-do the clutch pack inside a transfer case (if possible) rather than swapping entire units?

 

[Gix1k4]

Sounds like a chewed clutch pack to me, intermittently grabs. But I'm not the expert, I'm just going off info gleaned from literally dozens of 4x4 threads Kind of curious if, assuming someone has the time and patience, it's cheaper to re-do the clutch pack inside a transfer case (if possible) rather than swapping entire units?

That's what I'm thinking of doing. I found another low mileage (56000kms) t case at a local yard. I'll put it in the truck, pull the one currently in it and I still have the original one in pieces. I figure I can make 1 out of those 2, while still being able to drive the vehicle. With new bearings, seals and friction parts of course. I'll keep it as a spare.


I know that a press is needed to remove and reinstall the reluctor wheel in front of the t case pump housing. I have a 20 ton shop press that should do it, I was able to remove it from the old case with a bearing separator and a hammer, but will do this one the right way.....lol

 

[IllogicTC]

That's what I'm thinking of doing. I found another low mileage (56000kms) t case at a local yard. I'll put it in the truck, pull the one currently in it and I still have the original one in pieces. I figure I can make 1 out of those 2, while still being able to drive the vehicle. With new bearings, seals and friction parts of course. I'll keep it as a spare.


I know that a press is needed to remove and reinstall the reluctor wheel in front of the t case pump housing. I have a 20 ton shop press that should do it, I was able to remove it from the old case with a bearing separator and a hammer, but will do this one the right way.....lol

Having an entire spare transfer case is probably something some of the offroaders around here would be having their minds blown over

 

[Gix1k4]

Having an entire spare transfer case is probably something some of the offroaders around here would be having their minds blown over

That comes from my background. I run plow trucks, I've always kept a spare transmission on hand for every truck I've owned. 6 hours downtime is much better than 2 days or longer. They aren't brand new units, but definitely better than the alternative.

 

[IllogicTC]

That comes from my background. I run plow trucks, I've always kept a spare transmission on hand for every truck I've owned. 6 hours downtime is much better than 2 days or longer. They aren't brand new units, but definitely better than the alternative.

Good thinking. They don't have to be brand new, absolutely right. Old doesn't always mean junk, just like new doesn't always mean perfect. And saves you how many hundreds of dollars per transmission?

 

[IllogicTC]

By the way, I was thumbing around the Pam's Auto parts finder (located here) and found out they have a bunch of transfer cases they've pulled off cars that have come into their possession. Enter the info on the left, and option "NP8" for our transfer case. Starts at like $100 for the whole thing, it lists whether or not they include the encoder motor and apparently they'll take pictures for you on request. It's only ~$100 to ship one here to WV

It's also interesting to take a look at their "Guess That Wreck" game while you're there. They put their logo to all the pictures, so you see like a torn up Dodge Dakota with the FULL logo saying "Quality" and stuff, looks like a Carfax commercial lol. It appears what they do is purchase vehicles from insurance auctions, and part them out, so of course the part is used, a lot of the TCs they have listed are in the high 5-digit or low 6-digit mileage range, but if they are cared for they should work out okay.

 

[The_Roadie]

.. if they are cared for they should work out okay.

Huge *if*, if the reports are accurate of bottom-feeding cheap-ass clueless owners who never crack the Owner's Manual and don't understand the 50K fluid change REQUIREMENT on these puppies.

 

[IllogicTC]

Huge *if*, if the reports are accurate of bottom-feeding cheap-ass clueless owners who never crack the Owner's Manual and don't understand the 50K fluid change REQUIREMENT on these puppies.

Extremely huge if. But if it can serve its purpose of hobbling you down to the shop for a proper fix, having $100 tied up in a potentially-needed, maybe-someday part is a lot better than $1500

At least since it'll be just sitting there on a pallet or whatever, it's easy to work with and a partial or complete teardown for inspection never hurts. I mean really, the same gamble can be said for grabbing a used transmission but I guess that's the risk to be had with going with used.

 

[The_Roadie]

Yah, you're right. For that cheap, I *should* keep one in spares stock. I already have a dozen other anticipated items waiting around that I got for the occasional insane price, like $15 for a good used alternator.

 

[IllogicTC]

Yah, you're right. For that cheap, I *should* keep one in spares stock. I already have a dozen other anticipated items waiting around that I got for the occasional insane price, like $15 for a good used alternator.

lol $15 for an alternator ain't bad at all! At least those you can get tested at most auto parts stores, too. Don't know about the price to ship to your area, but probably still would be well under the list price of a new TC, and if it hobbles you to the shop at least then it served a purpose. Plus maybe having a unit on hand that you can afford to tinker with more could expand your already expansive knowledge of the system

 

[The_Roadie]

Heck, I hobbled 25 miles off a Colorado mountain with only fragments of a rear diff using FWD.

 

[IllogicTC]

Heck, I hobbled 25 miles off a Colorado mountain with only fragments of a rear diff using FWD.

But how to hobble if the TC input is shredded

 

[The_Roadie]

Then it would have been a long project of coasting, combined with slow uphill sections using a winch. Yes, a dead TC would ruin your day.

 

[Gix1k4]

Ok update to the update.

I borrowed a snap on solus pro from a friend and took the TB for a drive while monitoring the scanner. According to the scanner the service 4wd light is off, and the front axle is locked. I can hear the actuator on the axle whirr and I can feel the transfer case clunk into gear. Also, if I switch to 4lo it definitely goes into the lower gearing, but still only spins the rear tires.

Additionally, when I turn at full lock in 4hi, in either direction, there is no binding or "jacking" from the front end. (Like I get in my F250) Should I not be experiencing that, or would worn clutches in the t-case allow enough slip to override that? I'm now considering making a tool to bolt in place of the diff actuator that physically locks the shift fork fully depressed to be absolutely sure that the disconnect is engaging.

One more thing. What is normal as far as charging voltage on these things? I was always skeptical of anything over 14.5v. I witnessed as much as 15.3v on the solus, but never anything below 13.8(lights on and heater on high)