Service 4 Wd

[boatboy1]

I have a 1999 gmc sierra 1500 i had the service 4 wd light come on about a month ago. I read on a bunch of fourms that said change the pussh button on the dash so i did it worked for a while well now its back on and i have tryed a couple different things. New push button panel. Changed fluid in front end. Checked the wires goin to acutor on the front end. What causes this light to come on. Help please i got a race comeing up and i need the truck to tow the boat

[govtech]

cant help till you present a code from the TCCM

[boatboy1]

cant help till you present a code from the TCCM

There is no code the only codes the truck has is knock sensor 2 and evap sensor

[govtech]

from the TCCM,not the PCM

[boatboy1]

from the TCCM,not the PCM

Sorry it took so long but i just got my scanner and i got a code that is "U1026" loss of communication with atc

[govtech]

check your fuses for the ATC system

 

thats all you can do ...without some decent diag skills and access to service informaton and tooling,you'll have to take it somewhere and get it diag'd properly to spend money wisely instead of throwing parts at it right ?

 

may need a simple reprogram,who knows

 

good luck

[boatboy1]

its not thefuse i have checked it many times with a test light and mulitmeter and even changed the fuse. i am really good with working or stuff but this has me stuck i have a scan tool that scans transmission and gm only trucks this is the first scanner i have put on that actuly gives me that U1026 code i was try not to take it somewhere because where i am everyone want over $100 just to tell me the code not to even fixit.

 

 

thanks

check your fuses for the ATC system

 

thats all you can do ...without some decent diag skills and access to service informaton and tooling,you'll have to take it somewhere and get it diag'd properly to spend money wisely instead of throwing parts at it right ?

 

may need a simple reprogram,who knows

 

good luck

[fishbones182]

its not thefuse i have checked it many times with a test light and mulitmeter and even changed the fuse. i am really good with working or stuff but this has me stuck i have a scan tool that scans transmission and gm only trucks this is the first scanner i have put on that actuly gives me that U1026 code i was try not to take it somewhere because where i am everyone want over $100 just to tell me the code not to even fixit.

 

 

thanks

check your fuses for the ATC system

 

thats all you can do ...without some decent diag skills and access to service informaton and tooling,you'll have to take it somewhere and get it diag'd properly to spend money wisely instead of throwing parts at it right ?

 

may need a simple reprogram,who knows

 

good luck

 

 

I beleive you would have to have a tech2 code reader with the gm program to get an accurate code on these newer trucks. I think the cheap code readers just give you pretty much a generic code that dosent help too much at least this is what i have heard. Is there any truth in it i dont know.

[fishbones182]

one more thought check the trasnfer case module if you havent done so already. It may be a bad connection or the module itself going bad good luck

[boatboy1]

how do u check it?

 

one more thought check the trasnfer case module if you havent done so already. It may be a bad connection or the module itself going bad good luck

[govtech]

how do u check it?

 

one more thought check the trasnfer case module if you havent done so already. It may be a bad connection or the module itself going bad good luck

 

 

 

you need a schematic and check ALL the fuses and grds and have TECH 2 scanner ........and gm service information.....................

 

sorry all you can do is the fuse/grd thing,,, and the rest is a guess .....and money

 

you can try a known good TCCM also

 

good luck