service 4WD light?

no you get it scanned for codes to see what is wrong first it may not be the tcm. tcm is behind headlight switch

I have been having problems with my four wheel drive for over a year I was told by a mechanic who pulled the codes that it needed a new transfer case motor. I changed that and no change. Took it down to local transmission shop about six weeks ago and was told that the transfer case motor was not working (again) and that the front differential activator motor and the activator buttons on the dash were not working.

I finally completed all of the repairs and still no four wheel drive Had a friend clear the codes but not sure if this worked, service four wheel drive message came on again after about ten seconds.

I do not know what else to do!

the encoder motor on tcase has a high failure rate . what you will have to do is get it re-scanned for codes and get the code to us. it may be a wiring issue or a connection problem. what you can try in the meantime is to put dielectric grease at encoder motor on tcase and actuator connections on axle. it is about $2.00 at auto parts usually on counter it will say electric something like grease etc.

thanks, i will give that a try.

Also I have seen where the switch itself has a problem causing the problem you have described.

Best, Ken

4x4 drive push button. sometimes works , sometimes don,t

When it doesn't work, I need you to check to see if there is power to the actuator on the side of the transfer case. If there is power, chances are the actuator needs replaced. If no power, check wiring and harness. Follow wiring back until you find power and the problem. (could be switch too)

Let me know what you find or if you have other questions.

Joe

The other day my 4wheel drive buttons quit working and on my dash it says service 4wd. What would cause the buttons to quit working? please email me back soon as possible. thanks

Hi:
There is an electric 4wd actuator on the transfer case that electrically shifts for you. I need you to check to see if it's getting power.

Let me know what you find.

Joe

I put my truck on my lift and checked the transfer case and i finaly found a wire that was undone and i plugged it back in and it works perfect. Thank you for helping.

Service 4x4 light comes on when cold ,I tried almoast every thing except that small computer box behind dash panel.Replaced acuator in front axil the encoder in trans fer case,When you first start in morning or when truck sits for a while(it seemes when cab is cold) turn key the lites on dashblink for a second then service 4x4 lite stays on untill it warms up,you drive for a while shut it off then wait fo a while (about 10 min)then it goes out untill you shut it off,of gets cold .I'm a mechanic and it's really making me upset, i've had it on my scanner and I think my snap on scanner is to old,do you think it could be that computer behind the dash cluster? see what you think and please let me know,thanks

The first thing we need to do is have it scanned with a scan tool that can read the codes and go from there.You know as well as I do that's where we need to start.We can't just start guess what to fix that's expensive and time consuming.

Scan tool dont pick anything up , i replaced the contol switch on dash hoping it was that lol , none of the lights come on it still , i was driving one day and it came on , do you think its just a bad wire ? or the control module?

Thanks,

Jason Haglund

you need to find out the service message for the failure. a shop with a scan tool can pull this info for you and let you know where to look for the failure.

Roy

4x4 enguages but under load thefront axles disenguage ad service 4x4 light come on. what would cause this

It could be a few things. If the light comes on, have the computer scanned to identify trouble codes. That should indicate where the problem is coming from. Also, most parts stores will do it for free.

The truck is stuck in 4wd and the service 4wd light is on. When you push the transfer case selector swicth it flashes and yoiu can hear a clicking noise behind the instrument cluster then you can hear a buzzing noise down at the transfer case and it repeats once more but it never shifts back into 2wd. I have checked the switch and it is good. I also tried pulling the fuses to see if that would do anything. What do I do from here?

I am currently running another post with the exact same problem, mine would blow the atc fuse under the hood, I replaced the transfer case shift motor and fixed the fuse problem but now mine is also stuck in 4hi, I figured out that if I pulled the atc fuse the front axel actuator would disengage the front axel but when I put the fuse back in it would lock it in again and would not come out of 4hi. when I receive any more info on this problem I will post back.

The service 4wd light is on.
what does this mean, and what is it going to take to repair this? Also will I have to rest the light some how?

It would be best to get someone with a diagnostic reader/programmer compatible with Chevrolet systems (or dealer service center $$) to see if there is a code to work from. It can mean anything from low transfer case lubricant to a variety of electrical problems. I'm not sure about the reset. It may go off after addressing a simple issue (like fluid issues) but require a reader/programmer to reset for electrical issues. I havent worked with many 2000 and newer since I own a 1995 and 1999 and seem to get the 99 and older ones in to work on.

My service 4wd light is on and none of the lights on the push button are lit up. I changed the push button switch and that did not fix the problem any other ideas?

you can try to disconnect the 4 wheel drive module for 30 seconds and see if it comes back on. Sounds like the module needs to be replaced. You may have to go to a dealer and have a scan tool put on it and see if the module is getting communication.

is the module in the fusebox under the hood?

its behind the 4 wheel drive switch but above the drivers side fuse box. its a 2 connector module.

i hope this gets to soon, try to disconnect the fuse for 30 seconds instead of pulling the module out. This will do the same thing.

Tonite my service 4x4 light went on and all the lights on the dask switch went out, anyone know the problem or better yet the fix. I have a 2004 silverado crew cab.

Thank for any help.......will driving the unit damage anything.

I don't know that I can or can not help. But I don know that there is a good chance that more information is needed. Although someone may throw in a helpful post, My software needs more specifics.

What size truck K1500,K2500 etc.?

What size engine 4.3, 5.3 etc.?

Does the light say "4x4" or "4wd" or other?

Clarify the dash switch lights. All the lights on the dash? or is there a light on the switch?

IT would be helpful to get the codes out of the computer for this. I don't know that this is necessarily a mechanical isue, a Instrument cluster issue or a CAN issue.

My father-in-law just had a friend of his hook it up to a scanner and it said the encoder motor is bad. He has one off a suburban of the same year do you think that one would fit?

2004, k1500, 5.3...light on dash said "service 4wd"

im not 100% sure. You may wanna call a parts department and find out. What is the code that he got.

I keep getting a message to service the four wheel drive on the message center.
How can I determine what is causing this?
Will a DTC reader/scanner tell me the error code?
2000 model year with 32000 miles on 4.8 liter engine.


Thanks. :)

Yes, you should have it scanned for codes.Then post the codes for us please.

Thanks dennyp, I ordered a EQUUS 3100 - CanOBD2 Diagnostic Tool, as soon as I receive it I will let you know what DTC's come up.

Well, I hooked up the scanner and it said there are no DTC's stored in the vehicles memory.
I guess I will try to reset the monitors and do a OBDII drive cycle with the scanner hooked up until the Service four wheel drive warning light comes on again.

Today I pushed the erase button on the scanner to reset the monitors.
After driving about five miles with the scanner hooked up the service four wheel drive warning came on.
Still no DTC's.
I am thinking maybe a bad relay? (The relay that turns on the service four wheel drive warning)
I am buying a Toyota next time!

Your scanner might not be able to read transfer case DTCs. I use a TECH2 scanner.They run around $4,800.00

Okay, thanks dennyp.
I guess I will take it to the dealer because I am sure not going to buy one of the scanners you have.
I will let you know what they find.

The DTC that came up was B2725
B2725 - ATC mode switch circuit malfunction.

Here is a list of B codes:

https://www.2carpros.com/trouble_codes/obd2

I do not understand why GM does not have the code display on the message center instead of the service four wheel drive message.
But then, look how long it took them to make it so you could not leave your headlights on.

I have had the same problem with my 1500HD with All wheel drive transmission.

It is out of warranty but only has 28,000 miles and this message has been a problem. I had the switch module changes two times. Now, since out of warranty, I no longer take it to the Chevrolet dealer because of bad service. I brought to my regular guy but his testing unit could not come up with a code. He said to take it to Chevrolet because of a re-flash bulletin he found.

I am hoping the re-flash works because the alternative is quite costly. $500.00 for the motor module and $200.00 for the front axle module.

Let me know how you make out and maybe we can compare notes. :D

Here is a copy of a service bulletin.If your symptoms match this, follow the directions.

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



Models: 1999-2002 Chevrolet and GMC C/K Pickup and Utility Models (Silverado, Sierra, Avalanche, Suburban, Tahoe, Yukon, Yukon XL)

with Four Wheel Drive and NVG 236/246 Transfer Case (RPO NP8)




--------------------------------------------------------------------------------

Condition
Some customers may comment on the Service 4WD indicator illuminating. Upon investigation, the technician may find DTC B2725 set.

Cause
The condition may be due to a intermittent fault in the transfer case shift control switch.

Correction
Important: The transfer case shift control module should not need replacement. DO NOT replace P/N 15749703 unless diagnosis points to the module as the malfunction.

Replace the transfer case shift control switch using published Service Information procedures.

Parts Information
Part Number
Description

15709327
Transfer Case Shift Control Switch


Parts are currently available from GMSPO.