Jump to content

4wd Questions

67ChevyRedneck

Recommended Posts

67ChevyRedneck Enthusiast

67ChevyRedneck

Posted
Posted

Two years ago, my "Service 4wd" light came on fairly often. I installed a factory fog light kit and had to have the PCM flashed... after that the light never came on again. I used 4wd a couple times a month to climb a steep grass hill at my apartment after I load all of my dogs stuff when I go on trips. (Carrying two crates/food/clothes up two flights of stairs then out to the parking lot is a PITA so I drive down the hill right to my door :crackup: )

 

Starting three weeks ago it popped on when I was driving from Greensboro NC to Greenville SC. When I stopped for gas and restarted it went off and stayed off. It came on again friday night after about 20 mins of driving and again last night after about the same amount of time, turning off when the truck is restarted. My drive to work is only 8 miles and it's never come on during a short trip.

 

I spent a couple hours reading posts using the search last night and I still have some questions.

 

Questions:

 

1. Does the transfer case (or even front axle???) have a "low fluid" indicator that would cause the light to come on? (Got 2 conflicting answers in my research.)

 

2. My truck has 110K on it, is there any chance that it is an oil life monitor for the transfer case?

 

3. I also read in my search that 4wd will not engage when the light is on. So I tried it out last night when the light was on, and sure enough, 4wd worked just fine, engaged and disengaged without any funny noises. So, is there really anything wrong? Does that rule out the dash switch as being bad, or is that still possible?

 

4. I took the truck to autozone and they put their OBD II on it to check for codes. There weren't any, but he did say it may not read a non "check engine light code." Is that true? I'd hate to pay GM $80 to use their scanner and no codes show up.

 

5. My truck was originally an Indy truck for about 3 years. Is it possible corrosion is finally playing havoc with my sensors? Is there a diagram somewhere with all of them shown?

 

Thanks for any help. I like to fix my own stuff and I just dropped $900 on new BFG's and Bilsteins two weeks ago and I really don't want to take it to a dealer.

 

Edit: Also, there is no fluid anywhere under the truck. The transfer case is dry, the front Differential is dry, and the CV boots are clean and dry.

Lincoln30 Enthusiast

Lincoln30

Posted
Posted

I didn't spend nearly as much time analyzing my 99 symptoms when the service 4wd came on my 99. I just replaced the switch and it fixed the problem. The switch was far cheaper then $80 you will pay for diagnostics and takes about 10 minutes to put it. Mine went around the 100K mile mark.

c4cruiser Enthusiast

c4cruiser

Posted
Posted

A Service 4WD message in the DIC coupled with the indicator light on the 4WD switch going out and no problems like noise or loss of fluids, typically points to a bad switch assembly. The switch failure was intermittent. Sometimes it would go out for a few miles, sometimes for days. With the switch not lit and the Service 4WD message, the 4WD will not work.

 

That happened to my 99 and I got a new switch for $50 and installed it myself. You only have to pull the trim surround from the dash and remove the screws that hold the switch in place. Disconnec the wire harmess, plug in the new switch, re-attach and replace the trim. Done in about 5 minutes.

 

As far as fluids, my owner's manual has nothing specific about fluid service for either the front diff or the AutoTrac transfer case. I had both changed out at 65K miles and there was nothing that appeared wrong with either fluid. I guess that if you used the 4WD a lot, then it would be reasonable to do more frequest changes especially the front differential fluid. It's cheap and not that hard to do. The blue AutoTrac fluid costs some, but it's certainly worth changing a couple times over the life of the truck.

67ChevyRedneck Enthusiast

67ChevyRedneck

Posted
  • Author
Posted

Thanks Fellas :lol: The only difference with mine is that my switch lights never quit working.

 

The switch is at the top of my list before the truck ever sees a GM bay. I also plan on keeping the old girl another 5-10 years, so I'm being a little anal about it :)

 

Please, if anyone knows more, keep it commin' :D

 

2439419_41_full.jpg

 

2439419_42_full.jpg

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Latest Articles

  • Posts

    • Grumpy Bear
      Grumpy Bears 2015 Silverado 2WD

      By Grumpy Bear · Posted

      Notes 7/18/2026   3,400 miles on this batch of Mobil 1 Euro 5W40 since the GDI pump replacement. Alcohol runs very clean when ring seal is tight and the sump isn't getting hosed with fuel. Checked oil level at fill up today as is my practice and grabbed a white Kleenex to look at the color. What color?  I was going to change it but.....  
    • Another JR
      2 speed transfer case optional now?

      By Another JR · Posted

      4 low is really nice on steep boat ramps. 
    • Chuck FB
      Gas Prices

      By Chuck FB · Posted

      Interesting, I suspect I would have fueled up in Lee Vining as the day prior I would have filled up either in Laughlin or near there and maybe again before I entered Death Valley and once out the other side late that evening as I kept on driving into the night up near Lee Vining. Next morning I most likely fueled up in LV before heading over Tioga Pass into ( as I refer to it as "Yose .... Mite" 😁 ). And again that was 19 years ago but the price then must not have jumped out at me like the 5 bill a gallon theme of nutty cult hippy country Big Sir or head so far up their rear Aspen. I'd be curious to know where the highest prices are in the lower 48, I probably would not be far off to guess somewhere in Cali forn ie. Coldfoot and Prudhoe bay may have those prices beat but that is a whole other world up there and when prices are more normal elsewhere that is about what they can be up there I believe in no mans land. Anyway interesting that the 395 corridor is hosing people and the thing is, its tourist season and its not like there are a lot of competition options when driving up that highway from what I could see. Yup, big ole Boaterhomes and various other RV's ahead and behind me at the Yosemite entrance gate and they have to get their fuel somewhere.  
    • Atlas
      Gas Prices

      By Atlas · Posted

      Those can be high, as well as the big California cities. The ones that will pop your eyes out are the 395 corridor on the Eastern side of the Sierra Nevadas. Lee Vining, $7.19 for regular and $8.89 for diesel is what the Google said right now.
    • newdude
      2020 Trailboss 6.2 replacement

      By newdude · Posted

      Correct.  2019-2021 model years are serviced by a different p/n.  19420611.  Recall 2021s use 19420611.   The recall engines 2022-2024 model years are serviced with 12740076.     The difference between 19420611 and 12740076 is GM changed injector size for 2022.  The injectors are smaller on 12740076 with smaller injector bores in the cylinder heads to match the smaller injectors.  So you can't install a 19420611 in a 2022-2024, and you can't install a 12740076 in a 2019-2021.     Both engines are the replacement engine p/ns that are in the L87 recall.  So both of these are the updated engines.     Here's a version of the L87 recall with the p/ns for all the parts needed.    RCRIT-25V274-7075.pdf   Note it shows 19420611 and 12740076 with an asterisk to a footnote "Use the VIN and the GM Electronic Parts Catalog (EPC) to determine which part to order if two or more part numbers are listed for the same part, as it may vary by vehicle options."    

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...