Went Wheeling - Couple issues maybe connected. Traction control, 4WD etc.

Went wheeling to test out my newly lifted 08 tahoe BP. Its got a G80 rear and everything was going well until I was in 2wd in a sandy area I went to accelerate and it seemed to kick out of gear. Well thats what it felt like the RPM's shot up with zero resistance like you thru it in neutral with the pedal down and when the RPM's started to come down I heard some very light chattering. I put it in park and back in gear and off I went. I thought I may have kicked it out of gear but further in the day in 2wd this happened again. 4wd never happens. I dont think its the G80 rear as one tire would still spin if the locking mechanism didnt lock up. This is zero movement.


Second issue. When in 4WD. traction control light control light comes on flashing when in mud. I just hit the traction button to turn off but I thought going in 4WD Lo did that for you? No issues I got out of every mud and place needed but couldnt use low in the one attempt I tried in a very vertical area and rocky. I attempted low and it just hopped traction light came on and seemed loss of power which was scary on incline. 4WD HI got me out no issue.

Last issue and this happened before wheeling. I'm on 35's and when Im at like 55-60 and need to accelerate fast and really only happens when to the floor and high speeds. When I pin the accelerator I may downshift or not but when I do pedal to floor the traction light flashes for no reason then stops after the acceleration point. Doesnt seem to affect the acceleration as a whole. No check engine lights or codes.

Any help or suggestions on the 3? I checked ABS wires and connections to hub. I was thinking a bad wheel speed sensor.

dumb question, but are all 4 wires the same. height?

not in these trucks, but other gm's I've seen flash the tc light at wot if the ratio of size from to back to to far off. won't do it just diving around. but to the floor, if kicks tc in.

do you feel like it's actually limited power when the Tc light is flashing?

j91z28d1 said:

dumb question, but are all 4 wires the same. height?

not in these trucks, but other gm's I've seen flash the tc light at wot if the ratio of size from to back to to far off. won't do it just diving around. but to the floor, if kicks tc in.

do you feel like it's actually limited power when the Tc light is flashing?

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All 4 tires are brand new and same 35x12.50r20. This never happened with stock wheels in tires in the two months i drove prior but i never took offroad. The Tc like flickers everyonce in a while at wot at high speeds.

What gets me more is the jumping out of gear happened again but in traffic. I had to quickly flick the throttle while in middle of intersection turning left. i hit throttle fast off the line and boom out of gear and rpm’s jumped up. This time it went back to gear on its own when rpm’s went back down to zero. I’ve also had it jump out and won’t go back in unless you go back to park then drive. Trans fluid looks good, no codes or tc light when this happens. Pretty scary actually when i’m traffic I was sitting duck

I'm gonna guess and say 35"s + 4l60 = no bueno

ValleyTahoe said:

All 4 tires are brand new and same 35x12.50r20. This never happened with stock wheels in tires in the two months i drove prior but i never took offroad. The Tc like flickers everyonce in a while at wot at high speeds.

What gets me more is the jumping out of gear happened again but in traffic. I had to quickly flick the throttle while in middle of intersection turning left. i hit throttle fast off the line and boom out of gear and rpm’s jumped up. This time it went back to gear on its own when rpm’s went back down to zero. I’ve also had it jump out and won’t go back in unless you go back to park then drive. Trans fluid looks good, no codes or tc light when this happens. Pretty scary actually when i’m traffic I was sitting duck

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I've honestly never heard of that but I'm no auto tranmission guy either.

for the tc light you'll probably have to have a good level scanner and dig into that by first checking individual wheel speed and go from there?

maybe a tranny guy will have an idea about the slipping out of gear feeling. maybe losing line pressure? I believe a good scanner will show you the line pressure too?

Doubeleive said:

I'm gonna guess and say 35"s + 4l60 = no bueno

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Give em some faith I’ve had 35s on my 400,000 mile 4l60 for maybe 150,000 miles or more with no issues and I dog the shit out of it but then again I blew two out of both my Silverados with 35s-37s on them

ValleyTahoe said:

All 4 tires are brand new and same 35x12.50r20. This never happened with stock wheels in tires in the two months i drove prior but i never took offroad. The Tc like flickers everyonce in a while at wot at high speeds.

What gets me more is the jumping out of gear happened again but in traffic. I had to quickly flick the throttle while in middle of intersection turning left. i hit throttle fast off the line and boom out of gear and rpm’s jumped up. This time it went back to gear on its own when rpm’s went back down to zero. I’ve also had it jump out and won’t go back in unless you go back to park then drive. Trans fluid looks good, no codes or tc light when this happens. Pretty scary actually when i’m traffic I was sitting duck

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Did you just look at the fluid or did you smell it? Always smell it you’ll definitely be able to tell if the trans has toasted itself at least I did

I don’t think it would be the rear diff, I wonder if it’s the transfer case but I don’t know much about those. But you said it doesn’t happen in 4wd which makes me think it’s the tcase

I used to be a master mechanic back in the 90’s not saying I know much and here for your help because it’s strange.

fluid does not smell burnt.

Have a feeling TC light will be a speed sensor. Grabbing a bidirectional scanner.

Rear diff I ruled out. Def seems trans related. But this is like no slip I experienced in 20 years of being a service manager after tech. Only happens with a real harsh quick full throttle from dead stop. No real loud banging or crazy noises. Feels like a quick mechanical disengagement . Just revs up then down instantly when throttle engages. I may feel a little vehicle weight resistance like the trans was engaging for a millisecond. The more it happens the more info I obtain cause it’s so quick. I could simulate it or you could by right when you peg it to the floor you shift to neutral. Transmission is strong otherwise in all gear, missing and highway acceleration at 75-80. It runs great otherwise which gets me. Probably once I get scanner I’ll log trans pressure and see maybe a valve body or converter issue.

Trey Hardy said:

Give em some faith I’ve had 35s on my 400,000 mile 4l60 for maybe 150,000 miles or more with no issues and I dog the shit out of it but then again I blew two out of both my Silverados with 35s-37s on them

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I have ruined a lot of 4l60's I have no faith lol