Can anyone help me diagnose my 4 wheel drive or give a link to info? It is a 99 k1500 5.7L (same as the 98). The push button for the 4H blinks for a few seconds the goes back to 2H. Same with 4L. It did this once this summer, after a few tries it work, now it won't work at all. I don't want to start swapping parts, but i have no info on the axle actuator, transfercase actuator or tranfercase module. Any help getting me started would be appreciated. This is a bad time to be without 4 wheel drive.
I need help diagnosing my Chevy 4x4
- Thread starter 101prf
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Little6pack
Active Member
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- Jun 2, 2002
Are you doing this while driving or standing still?
My son has a 99 chev 4x4 I could ask him what he does. I think he also has an auto sense that puts it in 4wheel drive automatically
FYI On my 2000 & 2007 with the AutoTrack option you have to be stopped and the transmission in nuetral to engage 4 Low. 4 High you can hit anytime.
I don't know if your 1999 is the same system. :wink:
GerrywithaG
Member
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- Jul 22, 2010
not sure if this will help, but I ended up just changing the actual push switch and that fixed it..... 96 Jimmy
I have a 97 Tahoe with the pb 4wd system. It should engage to 4H driving down the road, or at a stop (in gear or neutral). When stopped, it seems to take a few seconds to engage, but always does. Pretty sure it won't go into 4L unless your in neutral (I rarely use 4L). Not sure if the ecm will verify the 4H request before you try changing the pb, if the ecm sees it, the problem is elsewhere. Check the chevy forums, there's a zillon of these trucks still on the road.
novaderrik
Well-Known Member
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- May 12, 2004
get a truck with a floor that looks like this, and 99.99% of all the 4X4 related problems that happen with late model trucks simply can't happen..
This was the old style 99 so it didn't have the auto-sensing 4 wheel drive but would engage while driving. I use 4H often, used 4L a couple times. Probably was the actuator but I replaced "All" the parts to be safe, now it will just take 5 years to pay for this repair.
get a truck with a floor that looks like this, and 99.99% of all the 4X4 related problems that happen with late model trucks simply can't happen..
That lots alot like my plow truck and I can't get that into 4H either, only 4L. I'm sure it will be alot easier to fix but I don't need to so that one can wait until spring.
chopped39
Well-Known Member
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- Aug 30, 2004
Get it scanned for codes. could be the switch or the actuator on the transfer case. You should hear the actuator switch when go from 2wd to 4 hi and 4 low while sitting still in neutral. I would get it scanned for codes before replacing anything. Most of the time its the actuator on the transfer case. That is an easy repair. Get a rebuilt one from napa. I have had quite a few actuators that were rotted out between the actuator and the case. Check the connector for corrosion.
I agree with getting it scanned for codes. Even though a CEL (check engine light) does not come on it could still have a code stored. There are numerous things that can cause the 4Wd to not work like the encoder motor, TCCM, switch, etc etc. But more times than not the encoder motor fails (actuator on the trans). But nothing is a gauranteed without proper diagnosing. HTH
DSR-TurboT
Making evil money
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- Oct 5, 2006
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IF it is anything like the late 90's Blazer 4wd it could be the pressure switch on the transfer case. That is what fixed my 96 Blazer. On my wifes 98 Jimmy it turned out to be the control module in the pass side kick panel. There is also the vacuum canister under the battery tray and the encoder motor on the transfer case too!
Glad my 04 Dodge Ram I bought to replace the Blazer just has the manual lever you pull to put it into 4wd!
Glad my 04 Dodge Ram I bought to replace the Blazer just has the manual lever you pull to put it into 4wd!
novaderrik
Well-Known Member
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- May 12, 2004
mine (the one in the pic) sometimes fights going out of 4H when sitting still, but if i just roll the truck forward or back a few inches it pops right out. never any problems going into or out of 4L as long as i remember that i need to be at a complete stop.
Funny thing is my 99 Jimmy is doing exactly what the opening posters is doing...
is there only one actuator to engage the 4hi and 4lo,,mine will in time go into 4lo and i hear it clunking when its doing its action,,i am parked in nuetral at this time...
if its one actuator then 4 hi should work,i had my seals changed in the front axels last summer and it worked then,copuld i be low on fluid???
That truck does not use vacuum for 4x4. If the front axle actuator was no good the transfer case should still engage and the indicator lights would show 4hi or lo. I would guess the transfer case encoder. Then the transfer case actuator or shift servo. Try wrapping on either of those first. 1 at a time. You could also slide under there and grab the front driveshaft and try to spin it to see whether or not the t-case is engaging.
get a truck with a floor that looks like this, and 99.99% of all the 4X4 related problems that happen with late model trucks simply can't happen..
Had more than 1 Chevy that looked like that. Memories....
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