Service 4wd light - No 4 low

[nluchau]

I am noticing every once in a while a Service 4wd light flash once and then go out when I start up my truck. When I try to access 4wd low the light just blinks and never goes to solid. My 4wd high and Auto work fine but Low does not. I have done some research and found this. I dont know if this persists to me or not. Is there anything else it could be.

 

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From GM-Tech at www.chevytalk.org

 

Well, how 'bout this TSB...

 

Inoperative 4WD/AWD Lamps, Inoperative 4WD/AWD System (Reprogram Transfer Case Control Module) #02-04-21-006A - (10/18/2002)

 

Condition: Some customers may comment that the 4WD/AWD indicator lights on the selector switch do not work, or the 4WD/AWD system may be inoperative and/or the service 4WD light is illuminated.

 

This TSB calls for a simple TCCM reprogram. I would think your dealer would check for updates to the software as a matter of course. Don't even need a TSB to see that if there are updates. BTW, there are three different TSB's for 2003 4WD problems.

 

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[Shaners]

It could need reprogrammed, or it could be a faulty switch. Alot of people have had to replace the pushbutton switch because of a service 4wd light.

[nluchau]

So if the 4wd low will not stay solid - could this still be the case? I suppose it could.

[nluchau]

Has anyone else experienced this? If so what did you do to resolve this issue.

 

The main thing is that when I push 4 low it flashes but will never turn solid. I guess I would like to know if I indeed need that switch or could it be something else

[bartlanz]

Not to sound synical, BUT, I know when I start my truck, a whole bunch of lights on my dash light up, (4wd service light included). I always thought this was normal, being that every vehicle i have ever owned has done it. When you are trying to change into 4wd low do you have the truck in nutral?

[oleander]

Bart,

 

Thanks for the reply. I finally got my truck in 4low by putting it in Nuetral. I believe since the pickup was purchased new that this is the first time I have had it in 4low. What happened is when I put switched to 4low I heard this noise like its engaging and then when I put the truck in reverse I had to give it some gas and then it caught and went in reverse. When I put it in Drive - I had to give it some gas and it like locked in like the tranny was slipping and then all of a sudden grabbed. Have you experienced this. Can anyone else describe their 4low to me?

 

Thanks for any replies.

 

I have a 2002 silverado z71

[bartlanz]

On my truck, when I switch to 4Low there tends to be a clunk and a bit of a kick. But only when the transfer case engages, not when I put it into drive, or reverse. But I have a 98 Tahoe, with almost 88K on it. I would be willing to put $ that there are some differences in the systems between our two trucks. I might recomend giving it a little more time between pressing the button, the light going solid, and puting the truck in gear. Also referance your user manual about this, it may also shed some light on your 4wd system

 

But I'm glad I was able to help you get your truck into 4Low, and save you a trip to the stealer

[juicy]

yes you must be in N to shift to 4WL

 

is seems kinda sticky at fisrt hand it should like the gears clam down

 

but all is normal.. you have a beast of a truck when in 4WL

 

nothing to worry about, move along

[Diamond Jim]

My 98 BurB has all the lights come on when you start it up, then it finishes the checklist and the go out.

 

But as has been said you have to be in (N) and under 3mph or stopped to shift into and out of 4LO. It also in your owners manual. As for the lights on the switches, sometimes they work sometimes they don't, and sometimes they work off and on. I have got to where I just ignor them.

 

I do like 4LO. Where I go fishing is about 4 miles from where I get onto the beach to the point. I put it in 4LO, get it up to 23MPH set the cruise control, and enjoy the ride.

 

One other thing I have a switch wired in to the line from the trnsfer case to the front thermal actuator. It allows me to disconnect the front actuator so it doesn't shift, and I can have 2LO. This is great as I tow a lot and its a lot easier to back up in tight places in 2LO.

[99GoldSilverado]

I kept getting the 'Service 4WD' light in the message center at random intervals. Sometimes the 4WD would work and sometimes not. Problem was the 4WD switch on the dash.

[electromag8]

[oleander]

Yeah I thought it was kind of weird when I either put it in drive or Reverse while in 4wd low. When It was engaged and I accelerated it took it alittle while for it to grab and then it took off. well I guess this is normal according to a few people. Is it like this for all trucks that have 4wd low? Also now since I got the 4low working I dont think I have a bad switch. Its just every so often I will see the Service 4wd light come on (only after I start the truck) just for a second and then never come back on for a good week or 2.

 

Thanks for the replies regarding this.

[officialfoxracer]

I had the same problem. I finally took my dash apart to find out when i move one of the two sets of cables around that go to this push button box, the lights came off and on with out the truck running. Moving so far would cause certain gears not to shift. So replacing the push button box would not work for me. All you are doing by do that is getting new fresh contact off the new terminals. In the next few days I am going to take apart the wire connections and bent them tighter so they touch better. Problem would be soluved. Try it yourself, put your steering wheel to low, put the gear shifter in 1st, and pull off your dash, pull out the 4wd button thing, and move around the wires with the truck running or not. Post findings...