"Service 4WD"

[DieselDixon]

My D.I.C. gave me this message today. Saw it right before I got home and before I shut down the motor I pulled out the trusty owners manual. It said to "stop driving, turn off motor and restart and if the message is still there have the 4WD serviced because there is a problem". So I turned off the motor and restarted and message came back. However, about 3 hours later I took a drive and the message never showed up, anyone seen this message before? The bummer is I have only used 4WD once and when this message comes on it disables the buttons on the dash so even if there isn't a problem you can't use it.

[Turbo Al]

testing

[Jack's Dmax]

I have already had the same experiance and it is something that the dealers are well aware of. My problem has been taken care of by my dealer.

Use the Search feature and you should find a great deal of information on this subject.

Good luck,

Jack

[Runaway]

Had it happen one time at about 2K. Same thing as you stated. Came out two hours later and never had the problem occur again, now at 25K+ and have used the 4x4 many times.

[DieselDixon]

Just got my truck back today, they reflashed the computer per bulletin 02-04-21-0003 and said, that will fix it. As long as it doesn't happen again that is fine with me.

[Jack's Dmax]

I hope that the re-flash will take care of your problems. There were parts replaced on my truck that were called for in a TSB that addresses the problem.

The service representitive told me that they didn't find any "codes" stored, but replaced the parts regardless due to the TSB.

Good luck,

Jack

[Jack's Dmax]

I hope that the re-flash will take care of your problems. There were parts replaced on my truck that were called for in a TSB that addresses the problem.

The service representitive told me that they didn't find any "codes" stored, but replaced the parts regardless due to the TSB.

Good luck,

Jack

[DieselDixon]

Jack, was there a bulletin number printed on your service invoice?

[TxDoc]

btt--any info on the bulleting?

[DA_MAXX]

Had same problem w/03 Chev D/A @ 5700 miles.

Tech Bulletin #03-04-21-001C, Diag Code C0327 Set. Dealer replaced:
12384996 Motor
12384990 Seal
12384988 Bolt (2)
12384989 Bolt (2)
26064275 Clamp
12479006 F-Sleeve
1052942 Sealant

Haven't had anymore "4wd" issues. Now 2 14000 miles.

Hope this helps.

[BassinRVer]

Did your truck stick in 4x4?

[Bill Knieper]

It is a problem with early 03s. The TB calls for replacement of parts. It does not matter if you ever use 4x4 the problem could still pop up from time to time unless you have the dealer fix it.

[2fast2]

I had a similar experience, ('03 2500HD D/A) with message "service 4WD" coming up one day at about 4000 miles. When that happened, there was no LED for 2wd, 4wd hi or low, and I couldn't shift the transfer case. Next time I restarted truck, the message was gone and everything seemed fine again. Dealer said he couldn't find any code and "couldn't duplicate problem." So they did nothing. Should I demand they perform the TSB directed service even though there was no stored code?
TIA,
Jim

[2fast2]

TTT
I'd really like to hear the opinions of the sage list members. Thanks!
Jim

[jbplock]

2fast2,
Dmaxallitech has posted the entire "Service 4WD" TSB on the other site. I would suggest you print out the TSB and show it to your dealer. IIRC, the owner's manual says it's OK if the message goes away after a shutdown and restart. If it keeps coming back you should insist that they (the dealer) fix it.

I took my 03 in yesterday for the "Service 4WD" problem. The truck is a year old with 18kmi. Up until this past weekend I had only seen 2-3 "Service 4WD" messages and each time the message didn't return after a shutdown and re-start. Per the owners manual this is "normal". However, last weekend I took a 5-hour trip and when I arrived at my destination I had the "Service 4WD" message. This time the message would return after a shutdown & restart but it would clear by pressing one of the DIC info buttons on the steering wheel. The message has continued to come on and the 2W, 4WH, 4WL and neutral indicator lights have also been coming on randomly. Seeing the 4WL light come on when I started up was not a good feeling

[2fast2]

Thanks jbplock, I'll look for that post and print it out to keep in my glove box. I've got a 1400 mile trip coming up for Thanksgiving vacation, and I hope it doesn't give me trouble on the road. So far it has been a one time thing.
Jim

[jbplock]

2fast2,
The dealer installed a new encoder motor and re-programmed the TCCM on my truck today. The service writer told me that inspite of what the owners manual says, they always repair the problem as soon as even one "service 4WD" message shows up. He also said they always replace the whole enccoder motor assy, not repair it. He said they had one customer with a truck stuck in 4WL that drove it (in 4WL) on the highway and burned out the transfer case. :eek:

[2fast2]

Well, let the run around begin...
I just got off the phone with the service manager at my local dealership. "NO, NO, NO, we never replace the encoder motor. There is sometimes a sensor that goes bad and we replace the encoder motor sensor." I gave him the TSB #. "Oh yes, I'm well aware of the service bulletin. But you don't replace the encoder motor, and we can't do anything unless some codes are stored." (Of course, when I had my truck in for service they claimed there were no coded stored.)
So I told him "Fine, I'll just take the truck on the trip and if it breaks down I'll just call GM and tell them to come tow the daln thing." Then he started to soften and asked me to bring it in to have his technicians recheck for any codes. Geesh, I hope this isn't the start of a disappointing relationship.
So far, they haven't been able to determine why my memory seat doesn't return to the correct settings (there weren't any codes stored!) and can't determine anything with the Service 4WD message.
If someone has the actual TSB, I'd like to print out a copy to take to the dealer. I'm not sure he is as familiar as he claims.
Jim

[flhrciblueice]

This is kinda long, but I think it may be what you guys are looking for.

4WD Switch Indicator Lights Flashing, 4WD Inoperative, DTCs C0327, P0836, P0500 (Replace Encoder Motor Sensor, Reprogram TCCM, Inspect Front Drive Axle Engagement Sleeve for Damage/Repair if Necessary #03-04-21-001C - (06/24/2003)
4WD Switch Indicator Lights Flashing, 4WD Inoperative, DTCs C0327, P0836, P0500 (Replace Encoder Motor Sensor, Reprogram TCCM, Inspect Front Drive Axle Engagement Sleeve for Damage/Repair if Necessary)
2003 Chevrolet Avalanche, Silverado, Suburban, Tahoe

2003 GMC Sierra, Yukon, Yukon XL

This bulletin is being revised to update the Correction and Warranty Information. Please discard Corporate Bulletin Number 03-04-21-001B (Section 04 -- Driveline/Axle).

Condition
Some customers may comment that the Service 4WD light is on, the 4WD system is inoperative, the 4WD switch indicator lights are blinking or that a grinding noise is heard from the front axle.

Service Diagnosis
Technicians may find DTC C0327 in the Transfer Case Control Module (TCCM) and/or DTC P0836 in the Transmission Control Module (TCM) and/or DTC P0500 in the Powertrain Control Module (PCM).

It is possible that the module may be in a mode that will not allow any shifts or updates for the software or calibrations. If this occurs, the TREC fuse (in the engine compartment) must be pulled and reinstalled after 30 seconds. This should allow further operation and service of the system. If a C0550 code is found, the TCCM must be replaced. All other codes should be able to be cleared, and the module reused successfully.

Correction

Important
For ease of reassembly, shift the transfer case assembly to 2HI for the NV263 (NP1), or Neutral for the NV246 (NP8) prior to removing any components. For information on placing the NV246 (NP8) transfer case in NEUTRAL, see the procedure at the end of this bulletin.


1.Remove the transfer case and front axle/engine skid plates (if equipped).
2.Disconnect and position the front propeller shaft aside.



3.Disconnect the transfer case encoder motor wiring harness.
4.Remove the three (3) bolts that retain the encoder motor to the transfer case.
5.Separate the encoder motor assembly from the transfer case and place it on a work bench.



Important
DO NOT REMOVE THE SCREWS INDICATED WITH THE (1) IN THE ABOVE ILLUSTRATION.


6.Remove the four screws on the outer perimeter of the encoder motor housing.

Important
For proper timing and ease of reassembly, hold the gear in place as your remove the cover from the encoder motor assembly with your thumb or finger.


7.Carefully remove the cover from the encoder motor assembly. The cover has a seal on the bottom side. Place the cover in a position to protect this seal from damage and/or contamination.



Important
Observe the location of the punch mark on the large gear in relation to the timing mark on the housing if the transfer case was placed in the 2HI for the NV263 (NP1), or Neutral for the NV246 (NP8). The timing marks should be within one tooth of proper alignment. If not, you must note the timing mark positions for reassembly.


8.Locate the two shims; one on the small gear and another on the larger gear. Set them aside on a clean surface for reuse.

Important
After removing the large gear from the housing, a dark gray phenolic spacer should remain in the casting where the bottom of the large gear resides. Locate this spacer and save for reuse.


9.Carefully lift the large gear from the housing. The sensor and wiring harness will come with the gear.
10.Disconnect the wiring from the sensor.
11.Separate the sensor from the large gear.



12.Ensure the phenolic spacer is in position in the housing.



Important
The sensor has two (2) keyed areas which must be properly positioned when reassembled. The bottom of the sensor has a positioning pin that must be positioned in the cavity in the housing. The sensor key must be properly positioned over the key way in the large gear. Follow the step by step instructions below for ease of assembly.


13.Connect the wiring harness to the sensor and position the sensor into the housing with the positioning pin seated in the housing. The wiring harness connector wording (TOP) must be visible.
14.Carefully position the large gear to the sensor aligning the key way slots. Just begin the insertion of the keyway over the key; rotate the gear to achieve proper orientation of the timing marks and then seat the gear.
15.Reinstall the shims on the small and large gears.
16.Ensure that the wiring harness is properly seated in the housing.
17.Replace the encoder motor cover seal.
18.Reinstall the cover with the four (4) new screws. Tighten
---Tighten the two (2) long screws to 3.38 N