Service 4wd light

[chevelless502]

My dad has a 2000 silverado 4x4. The service 4wd light comes on from time to time on the dash. Evrything mechanical is ok. Anyone have an idea of the problem? Thanks.

 

Andy

[DSZ71]

this is a common problem for the newer GM trucks, just take it in to the dealer and have the switch replaced. If its under warranty its no problemo!

[silverado man]

Yes it is a common problem on these newer trucks. You just has to replace the switch in the dash. That part number if you want it is 15709327 and you can order the part from one of the supporting vendors Partszone or GMpartsdirect.

[99silveradoz71]

Had mine go on my 99 with similar symptoms...light went on and off.

[Shaners]

If you are out of warranty, don't pay the mechanic to replace the switch. It's a simple job that just about anyone could do... just buy the switch and do it yourself.

[Nick2000Gmc]

Mine went on my truck too, When it did it too me the light came on so i stopped and turned the truck off and on. When I turned it back on the light went out i think ( anyways I tried to put it in 4hi and it wouldn't go and then the loght went on. So i tried 4low and it went right in. I had mine replaced under warranty and the mechanic said they were like 70 canadian and that they don't even troubleshoot for it. They plug the computer into the truck and it says the switch is bad. So it wouldn't hurt to take your truck to a gm dealer ( not sure if a regular odb code reader can pick that u or not ) and have it checked. I have never had a problem since.

[Larry]

Have you all noticed a trend in the growing number of forum threads on this subject….not only on this site but all truck related website discussion forums?

 

After spending a few years working on the Chevrolet Technical Assistance hotline helping dealers diagnose problems, I will tell you the push button systems, Autotrac transfer case (option code NP8) as well as the standard electronic shift transfercase found in the HD’s and older C/K trucks and SUV’s (option code NP1), are very unreliable systems. Just to give you an idea of how high the failure rate is on these are…right now GM has 7 different bulletins to address different Service Transfercase light concerns with about 5 more unpublished PI’s. I would love to be able to obtain warranty data or the electronic transfercase part turn ratios that GM Service Parts Operations is seeing on these.

 

I guarantee that warranty dollar expenses for GM must be extremely high but at the same time GMSPO part sales for related parts for this system must be a nice profit center as they have exclusive rights to these parts (encoder motors, transfercase control modules, button assemblies) as they are not available through the aftermarket (Napa, Autozone, etc).

 

For those of you that have known me for a few years remember that I have always bashed electronic transfercases every chance I get. I am neither against electronics nor technology, I am just against technology that is not needed. What is wrong with pulling a lever anyway!? The manual shift transfercases have ZERO bulletins or PI's....hmmm.

 

Contrary to what a lot of your dealers are telling you, manual transfercases are still standard equipment on Base and LS model Silverado’s and comparable Sierra’s....you do not have to settle for this system. However, Chevrolet LT and GMC SLT models have NP1 and NP8 as standard equipiment as well as some LS and SLE models due to seat configurations. All SUV's and S-10, Somoma's, Colorado's, Canyon's have NP1 or NP8 as standard equipment as well...except tracker. It really sucks that GM relies so heavy on JD Power data that they have made this unreliable system standard on almost everything.

 

I went well out of my way when I bought my 98 Z71 to find one with a manual shift transfercase as well as my 01 HD. My wife’s Tahoe was a different story as AutoCrap is standard equipment…and guess what…at 2900 miles the encoder motor was replaced due to a Service Transfercase light. Granted, the wife will not use 4wd much but when you need it….you cannot rely on it to work.

 

Current replated bulletins:

 

1. #PI01410 Poor Performance from a Stop in 2WD , Auto , or 4WD Hi - 233 233E 236 243 246 263 4L60E 4L80E chuggle DTC gear hesitate L31 LL8 LM4 LM7 LQ4 LQ9 LR4 Lo4 NP1NP8 no P1875 power surge TCC - (Oct 7, 2003)

2. #PI01267B Service VME - Service 4WD Light On No Codes Besides U1000 Codes - 246EAU 263EAU AWD case communication DTC hi2 hi4 lamp light lo4 MIL NP1 NP8 U1000 U1024 U1026 U1041 U1064 U1096 U1152 U1300 U1301 - (Oct 1, 2003)

3. #02-04-21-006B Inoperative 4WD/AWD Lamps, Inoperative 4WD/AWD System (Reprogram Transfer Case Control Module) - (Aug 18, 2003)

4. #PI00925C NP8 and 8.25 Front Axle Growl Noise in 2WD May Not Occur in 4WD or AWD - case differential drive drone hi2 hi4 moan transfer - (Jul 1, 2003)

5. #03-04-21-001C 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 - (Jun 24, 2003)

6. #03-04-21-005 Service 4WD Light On, 4WD Inoperative, Diagnostic Trouble Codes (DTC) C0300 and/or C0305 Set (Reprogram Transfer Case Control Module (TCCM)) - (Jun 5, 2003)

7. #03-04-19-001 Info - Use of Synthetic Front Axle Lubricant for 4WD Vehcles Sold in Cold Weather Climates - (Feb 11, 2003)

8. #VSS20020131 Adm Msg - Inoperative 4WD/AWD or Service 4WD Indicator (Admin Number VSS20020131 10/4/02) - (Oct 4, 2002)

9. #PI00462A Inoperative 4WD AWD Lamp - Update to TSB 02-04-21-006 - (Sep 30, 2002)

10. #02-04-21-004 Service 4WD Indicator Illuminated, DTC B2725 Set (Replace Transfer Case Shift Control Switch) - (Apr 15, 2002)

11. #99-04-21-002 4WD Transfer Inoperative (Replace Actuator/Shift Detent Plunger) - (Apr 1, 1999)

[nonstop]

Hey Larry, what about the power window regulators, are you seeing a high failure rate on these?

 

These poorly engineered gizmos that GM has are really starting to piss me off.

 

[sledtrash]

So my problem is a little different from what I've read so far on the forumns. I was using my truck for work on a mountain (hauling chainsaws, water, and pesticide for the company I worked for at the time) I had it in 4-low being as it was a 2-track in very steep conditions. We stopped on a slope and I put it in park and jumped out to move a rock, it held in park long enough for me to shut the door and then started rolling with a clicking noise the whole time. I got back in it and parked with the nose into a bank so it couldn't roll, but I noticed the service 4wd light was on (no problem since then with putting the transmission in park while on slopes...). I didn't worry about it until we were off of the mountain and I was needing to take it out of 4wd-low so I could drive at faster speeds. I'd push the button and the little indicator lights would just flash at me, no change in gear selection. We managed to get a call through to the local GM dealership and they advised us to bring it in. Well we were 400 miles away no way I was going to drive it 400 miles in low range. Their next option was a tow truck we were still on non-maintained roads so not an option, so we told them to tell us how to get it out. They told us to disconnect the battery and let the computer drain out of power power (resetting the system?). We did that and the light turned off, they told us that the problem was fixed and we could go home, not even needing to bring it in.

 

Well a year and a half later (around 35000 miles) after much use with the 4x4 and no lights coming on or anything.... I needed to replace the u-joints in my front driveline. I un-hooked the front clamps on the driveline and found out that it wouldn't turn in the transfercase (this was in 2HI on my indicator on the dash)... I then "put" the transfercase in nuetral according to the process specified in the manual, crawled under it and stil no turn on the transfercase output.

 

So could this problem have been caused by the situation on the mountain?? because right after that trip my fuel mileage on the highway went from a amazing 20-22 to 16-18. No changes in driving styles and tires or anything.

 

The whole reason I checked the u-joints is because I had a bad vibration, well I found out that one of the bearings in the diff (the one that carries the right side axle shaft before the locking hub) is bad. So my guess is that my 4x4 in the transfercase has been running for 35k miles (since the mountain incident)((note) but I can tell that my front locking hub works I can feel it engage and disengage) running through the positrac diff all the power would go to that right side (because the left side drivers side is directly hooked up to the Cv with no locking or unlocking hub.... Am I way off on my assumption???

 

So what could be my problem in the transfercase? The light came on that one time but I have never seen it since that point... I have noticed a drag in daily driving (when it say's that it is in 2Hi) The transfer case will shift between 4HI and 4Low no problem and it says that it is shifting out, but the output for the front driveline never has free wheel.

 

Thanks guys!!!

[Westlotorn]

The Auto Transfer Case 246 always has drag on the front driveline. You can rotate it in 2wd but you feel the drag as the clutches slip inside. It takes a good amount of twist to turn it with the front wheels off the ground and the trans in neutral the drive line can be turned to remove the ujoints bolts. I believe this is normal for this transfercase.

[Michel GMC]

I've been having the same issue with my 2014 Silverado. Since they have made that software update for the transfer case, it is the second time the message has came on. Now only that I need to bring the truck in for the sixth time, every time I bring it in my wife has to take time off her work (can't drive as I had neck surgery). Now to top things up, the other day a "Faulty engine power" message showed up and all this with less then 10,000 KM on the vehicle.

[eihab]

Hello Gents,

This is the first time for me on this forum. I have a GMC Yukon XL 2007 with 4WD. I started receiving the Service 4WD note in the Information center last year but it was intermittent. I receive now the code 0300 with continuous display of the Srv 4WD notification. I hooked up my scanner and displayed the data of the TCCM and it showed that the rear prop shaft sensor is dead. I changed two sensors on the end of the Transfer Case without any luck. I have two questions for you experts: 1- Which sensor of the two is the rear prop shaft sensor and which one is the VSS?

2- where is the exact location of the TCCM and its ground on the chassis?

Only the Auto 4WD function doesn't work. 4WD Hi and 4WD Low both work, but when disengaging, I hear and feel a big thud.

I think the problem is a bad connection but I need to know where to look.

Any helpis really appreciated.

[Tedlafond]

OK I have a strange fix for my 2003 envoy..what's the temperature? Anytime the outside temp falls below 55 degrees I have issues with engaging 4wd...the TCCM in my vehicle is located under the dash drivers side...I decided to experiment..I started my vehicle,turned the heat on to the floor full blast for about 20 minutes.. got it nice and hot...I don't know if the TCCM is just cold or what not,but ever since I started heating up under the dash,i never had a problem...I never have any problem with it,if it is warm outside...hope this helps and it's a free fix if it does