03 LB7 with some issues

Hey all! New guy here, so feel free to flame me if I didn't search well enough:

Hey everyone, I've posted up on another forum but wanted to see what you guys thought as well. I picked up a 2003 2500 with the LB7 for $500. It runs perfect, just got new injectors, new fuel lines, new fuel tank, new tie rods/ball joints/etc. It was a smoking deal I couldn't pass up - only 315,000 miles. Standard midwest rust on the rockers and the cab corners, but that's an easy fix.

Only thing.....it feels like the transfer case is stuck in neutral. At first, there was no power to the 4wd selector, so I checked the TREC fuse and it was blown. I replaced the fuse, and the neutral light comes on and stays on, and the truck says "service 4wd" and "Shift range inhibited". When shifting through the gears, it shifts from PRND321 just fine, but from Reverse to Park, there is a grinding noise (which makes me think that it's the transfer case).

Any ideas? I don't have a way to pull codes, otherwise I would do that. Tell me if I'm way off base here, but could it be the encoder or the TCCM?

Any input is greatly appreciated!

Welcome aboard!

Looks like you got a good deal. Your issues sound simple, one way or another.

It sounds like the transfer case is in neutral. The "grinding noise" you are hearing is the parking pawl looking for a home. This happens anytime the TC is in neutral, and you shift out of park. The drum spins, and moving back to P engages the parking pawl, and it will skip over cogs until it catches one. A shutdown or restart lets it catch.

The "Service 4WD" and "Range Inhibited" messages can mean a couple things, but they may be independent of one another. If you select a mode and it flashes an indicator on the button cluster, it's either in transition, or unable to complete the shift. Any time you select a mode, you should hear the encoder shifting (electric motor sounds and a clunk). If you hear nothing, and lights continue to flash, either conditions aren't correct for that shift, or the encoder isn't responding or is obstructed. Is there ANY indication of ATF leakage near the rear of the TC? If so, you may have the "pump rub" issue, and the fluid is too low. Check the TC fluid level. Not a real big deal, if so, but it must be addressed.

"Range Inhibited" is usually an issue with the NSBU module (located on the tranny at the shifter input). Any time it's not signaling right, it can produce the message. You'll need an advanced scanner to read the codes. Simple scanners/readers will indicate a "P0700" code, meaning there are TCM codes present and the MIL is commanded (SES lamp), but doesn't indicate which code. You really need a capable reader/scanner to go further.

"Service 4WD" can mean anything from a bad button cluster (common, and cheap to replace), to a failed encoder, or any wiring or connector in between. I'd start with checking electrical connections, before throwing parts at it. Not remotely likely to be the TCM, but stranger things have happened.

Thanks for the detailed response!

There is no indication of leakage from the transfer case - and I’m confident that the previous owner didn’t try and clean it up either. The truck also ran and drove beautifully before this issue. I bought the truck from my work, which is a trucking company - this was our plow truck for the lot.

Before I noticed that the TREC fuse was blown there were no lights on the transfer case switch. When I replaced the fuse, the only light that comes on is the Neutral indicator on the transfer case switch and when you try to press any other button, nothing happens and there’s no noise from the switch or from underneath the truck.

If I pull the encoder motor can I manually put the tcase in 2hi? My assumption would be if I can, then that would allow me to isolate the problem if the transmission will engage when the transfer case is in gear.

As an aside, it does have some other wiring issues so wiring could also be the culprit - but those are with interior electronics.

How are/did you shifting the TC into N? The engine doesn't need to be running, but the tranny must be in N, with zero ground speed, and the key must be in the RUN position. In any case, when you select any range, the lights on the button cluster should flash during the shift, either until the shift is complete (then the new position should light), or it fails, which can take up to 15 seconds or so. If they aren't flashing, the switch is suspect. Failed encoders are extremely uncommon, while the button cluster commonly failed early. Mine did when the truck was a few weeks old, and a TSB was issued for the condition (bad factory button clusters). The blown TREC fuse is curious, which may indicate an issue with the encoder, or associated wiring. I think I'd start with a close look at the connectors and wiring. A blown fuse indicates an overloaded encoder or a short in a connector or wiring. Also curious, shifting in/out of 4x4 should also shift the front axle, which should also be noisy, but you may not hear it with the engine running, and can be confirmed by checking the front prop shaft for lockup (jack one wheel and spin it). If the axle isn't shifting, it may indicate an issue more common with both, or at least the encoder. If I recall, front axle lock is initiated by the TC shift into specific modes, so it may or may not be dependent on the encoder position. The service manual doesn't specify, that I can find.

According to the service manual, the TC can be manually shifted once the encoder is removed. It actually specifies a "crescent wrench" as the proper tool to shift it, but doesn't specify a direction or how much. It also specifies the TC should be in neutral when the encoder is removed/replaced, but doesn't specify any consequence if it isn't. I'm assuming if you manually shift it, then install the encoder, the encoder should be indexed to match, one way or another. The encoder mounting bolt torque is 15 ft/lb with a new gasket. Give it a try and let us know how that turns out.

All that said, looking at the electrical diagrams, it appears the front axle is enslaved by the transfer case range selection. Also, all function and indication circles back to the button cluster, and its integrated "solid state logic". Your specific issue, working fine, then it didn't, brings me back to the button cluster, or some issue with the wiring and/or connectors.

Sorry, allow me to clarify. When I first purchased the truck, I fired it up and received no warning messages. When I attempted to put it in gear, I got the "Shift Range Inhibited" error and none of the lights on the 4x4 selector switch were illuminated. After further investigation, I saw that the TREC fuse was blown, so I replaced that, and the only light illuminated on the switch was the "N" - attempting to push any other buttons resulted in nothing. At this point, I received both the "Service 4wd" and "Shift Range Inhibited". My gut tells me that the shift range is an issue because the transfer case is stuck in neutral, but I could be wrong.

I have ordered another 4x4 switch and another transfer case motor just because they were "cheap" in the grand scheme of things, they'll be here tomorrow.

I also got the batteries replaced under warranty as they both had dead cells, but I have not installed those yet.

The truck lived life as a plow truck and from what I gather there are also some wiring gremlins with the interior, so I did clean all the grounds and checked ALL the fuses to see if there was anything else suspect and nothing popped out at me.

I'll crawl underneath and check the wiring when I have a moment to do so.

For now, I'll put the new batteries in, then report back, then replace the switch, then the motor and see which, if any, does the trick.

Sounds like a good plan. If the TC is "stuck" in neutral, you should be able to find out if it's internal or external by attempting to shift it manually, if it comes to that. With the encoder removed but electrically connected, you should be able to confirm its function (it moves or it doesn't). Make a note of the position of the shifter and encoder before moving anything. They'll have to be matched upon reinstall. If you replace the encoder, it and the TC need to be in neutral position, or they will cause calibration issues with the logic at power up (according to the manual).

315K miles, primarily as a plow truck, is a pretty good test of the transfer case. I wouldn't be surprised if you find it's due for overhaul. Overhaul kits are available and relatively inexpensive for DIY. Remans are spendy, while wreck take-outs are generally less than half the cost.

I went out and threw the batteries in it, and am still getting the same issues. On another note, this time I did get all of the lights in the 4x4 switch to light up upon starting, but attempting to switch it out of neutral, there was no further action from the switch - the "N" light just stayed illuminated. It seems that there are quite a few electrical issues going on, this time when I started it with fresh batteries I lost all my gauges as well - but I did push the E-brake all the way down, maybe I hit some wires....I don't know.

Someone had made mention that it could be the Body Control Module that is bad, it did have some weird electronic issues in the past (the AC intermittently working, the window switches intermittently working).

Maybe I bit off more than I can chew here, but at the price point I'm not overly concerned.

The BCM could be suspect, but less likely than other possibilities. 2003 began the multiplexed electrical control system, which makes it much more vulnerable to stray voltage and faulty grounds. It's great when it works, and helps protect component electronics, but significantly more difficult to diagnose issues, in my experience. You may try an electronic reset. Disconnect both Batt+ terminals and ground one to chassis for about 30 minutes. This should reset the computers and discharge any residual power. Reconnect and wait another 30 minutes before KEY ON. Key on, but don't start. Cycle it on/off a few times, about 5 minutes between. This forces a new set of start-up diags, disregarding previous (don't do this immediately prior to a smog test, or it will fail).

I'll give that a shot and report back as well.

Well I was finally able to dedicate some time to this beast.

The transfer case motor was bad, so I pulled that off and manually selected 2hi. She runs and drives like a champ now, so I’ll get the new motor installed and then start chasing down the other electrical issues it’s got.

I know it has a parasitic drain somewhere because if it sits for 3 days, the batteries are dead.

Additionally, I’ve got all of my gauges back and the DIc works just fine so I suspect the batteries were not charged enough.

If you have to leave the truck set for a few days again, disconnect both batteries and check their voltage. Check the voltage again when you return. They shouldn't drop more that a couple tenths. If more, such as a full volt, that battery is bad. Having one bad battery in a pair will take them both down, faster than a lone battery. It's better to run on one good battery than have a bad one still connected (until you get them replaced). The bad battery will eventually kill the good one.

Quote:

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Originally Posted by DmaxMaverick

If you have to leave the truck set for a few days again, disconnect both batteries and check their voltage. Check the voltage again when you return. They shouldn't drop more that a couple tenths. If more, such as a full volt, that battery is bad. Having one bad battery in a pair will take them both down, faster than a lone battery. It's better to run on one good battery than have a bad one still connected (until you get them replaced). The bad battery will eventually kill the good one.

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Both batteries are branded new. Both of the old ones had dead cells, strangely enough. As for now I have both disconnected to prevent them from draining.

OK, that's good. 3 days to drain the batteries is pretty quick. Have a close look at any aftermarket anything attached. Or perhaps a bad relay or switch somewhere. Visit it in complete darkness and look for a dim lamp, which may indicate a short.

Finally drove her home, and she drives like a dream. I still need to put the new t-case motor in, for now I just don't have one on there. I have the new one, but couldn't get it to line up with the nub sticking out of the tcase. I'll fight with it some more when I can.

Started to dig into the wiring - which is A NIGHTMARE to say the least. In addition to this, there is still all the wiring for a remote starter that's still down there - I just haven't been able to trace back all of the wires for that yet. Here are all of the wires that I pulled out that were going to nowhere so far. There were wires that were powered with no ground, 3 different tracking devices, all sorts of fun stuff:

Pile of Wires

Also - Can anyone tell me what fuse or relay this is, and what the correct fuse/relay number is so that I can replace it?

Weird Fuse

Lastly - What am I missing here? Engine Bay Picture

Sorry for the links, I don't have a good way to post inline.

Edit: Last thing to add, all of my gauges work perfectly except the temp gauge. That one doesn't read anything at all. I drove it 40 miles and it still sat on the low mark. Any thoughts there?

Quick update!

All of the windows now work perfectly - turns out both circuit breakers for the windows were completely missing.

The parasitic draw is gone, battery stays charged.

I've replaced both front and rear bumpers (they had seen better days). I still have a p/s fog light that is broken, so I've got those ordered.

Now the bad:

When I hit the easy exit button on the door, the seat moves all the way forward - how do I fix this?

When I turn the truck on, the driver's side mirror moves all the way to the right - so much so that the motor itself is clicking. How do I reprogram that?

My temp gauge does not work ever, and all of my gauges will randomly stop working completely (but the dummy lights and the DIC still work fine) - any ideas on this?

It sounds like you're still having issues with BCM communication. This can effect the seat/mirror positions, as well as instrumentation. If it were only one or the other, I'd suspect that independent system, but it isn't. To start with, you'll need a Tech II or equivalent to check the BCM communication, outside what you already know. I'd start with decommissioning all key fobs (procedure is in the owner's manual). This should remove any action commanded with the key fob associations until you reassign them. Keep the fob association to none or only one until all the issues are resolved to reduce/eliminate association conflicts. If the seat and mirror issues continue, focus on the BCM and associated grounds and connections. If the procedure isn't responsive at all, suspect a bad BCM. BCM failure or logic conflicts can affect multiple systems, even if they are seemingly unrelated. Instrumentation and key fob associations are BCM functions, at least in part, and is the only common logic system to both. The BCM is located behind the column dash panel. Beware of ANY bright yellow connectors and harnesses. These are airbag system connections. I suggest pulling all the airbag/SRS fuses before going into that.

Thanks, I'll give that a shot. What grounds are associated with the BCM?

If you don't have diagrams (or a service/repair manual in general), now would be a good time to get one. The alldatadiy.com manuals have good diagrams (with troubleshooting charts) included, as well as other necessary sections. I haven't visited the 2003 models in a while and don't have current access to a manual. The diagrams will show all the connections and grounds, as well as their locations, relevant to the systems.

Will do - I appreciate the help. I'll be sure to update this when I figure it out.

Update:

The temp sensor issue was due to the fact that the wires to the sensor on top of the block had broken. I cleaned them up and threw some butt connectors on it and the temp gauge works perfectly now.

I’m still suspect of the BCM, but when I get some more time I’ll check all the grounds and clean up some other stuff.

One piece at a time, if you have to.

After your finding with the temp gage, chase each of the others just the same, as well as the grounds. Also check the BCM connector, making sure it's clean and all the pins are engaging.
In the meanwhile, try the key fob reset/remove procedure. It may clear up some of the BCM issues, maybe all (optimistic).

At this point I've run all the wires down and there are no other breaks or frays in the wiring. I'm waiting for the new BCM and will get it programmed and then I'll report back. Hopefully this will fix the last of the lingering issues.

Update.

I’ve replaced the BCM and have installed. Fixed some of the issues.

Here’s what I’m left dealing with:

-Rear windows don’t roll down
-left turn signal only works about 70% of the time
-door locks don’t lock the doors. You can hear them moving, but hitting the lock button on the remote after they are locked unlocks them. It’s weird.
-only my drivers side front speaker works.


I’m beginning to think that this thing was either struck by lightning OR someone tried to jump start it with a semi and didn’t do it right, which caused a lot more electrical issues than I realized.

You may be right, about the voltage spike. I've seen similar on one of my older vehicles. Tried a jump start with a welder (hey, it was handy), friend who was "helping" thought he would do me a favor when it wasn't quick enough, and flipped it to 28V. Fried every bulb that was on (light show), a bunch of fuses and switches, and half the glow plugs I was cycling at the time.

Anyhoo....
If you're still having issues with the door locks and windows, if you have good power, that leaves the RKE module (transceiver module), the driver door controls, or the driver door harness (may be more likely if the driver door speakers don't work, but they may have common issues of their own, and if it has the mirror signal indicator, it may be shorted/open, effecting the left signals in general).

It’s really the only thing that make sense. Both front door modules have been replaced and they work fine.

It almost seems like it got an electrical spike that fried everything. Or I’m missing something.

The weird thing is the HVAC works perfect, and the rear defrost works perfect, as well as the power rear view mirror and all of the steering wheel controls.

I still have the weird issues of the easy exit seat moving all the way forward, and the driver side heated seat powers on for about 30 seconds and then the indicator lights shut off.

It’s perfectly driveable but the electrical gremlins make me want to take the first $3500 someone is willing to throw at me haha.