abs light speedo freaking tranny slipping ???? wth is going on

[nicholsyukon12]

i hope i am posting in the right space on here :/ i'm not sure where this goes but since i have had 2 mechanic shops bewildered i figure i might as well ask

 

i recently bought a 2004 yukon xl and it had abs start coming on , it is 45 grand miles and now it has all this going on :

 

abs light on

 

traction control goes off

 

won't stay in cruise control

 

"slips" out of gear going down road, rpm s go thru the roof while tires feel like spinning

 

speedometer violently aggitated

 

hard brake pedal

 

service tire monitor light

 

it is a mess in general, thing is, its only intermittent starting out down the road but gets really bad a few miles down starting the gear problems, the abs is now staying on constantly. i have taken it to two garages and they have ran the computer thing on it and came up with codes they haven't a clue about, one place replaced a sensor on back of transmission and that didn't work so they want me to leave it but i am a little leary of doing that.

 

hubby thought it was abs unit going bad so he undid it and tried it out w/o the module, it still done it

 

does anyone have any idea, the mechanics around my area are clueless

 

any help is tremendously appreciated

[8.1HD/ALLISON]

Need to check codes and start diagnosis from there.

 

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[nicholsyukon12]

is it possible to get the codes from the people? one place only flashed a paper with the codes written on it lol and the other i didn't get to see, it's kinda like they don't want anyone to see them :/

 

and my oldest son wanted me to add that the tire pressure monitor was prob b/c the people who had it before me put some sort of 20 in rims on it

[txab]

If the tire diameter has been changed from what it left the factory with, the speedo will need to be recalibrated for it, if it hasn't been done already. Certainly you need the codes that were pulled from it. Find a better mechanic

[Jsdirt]

Yep - I accidentally changed the tire size parameters when installing a Hypertech program. Dash lit up like a Christmas tree, and exhibited the same symptoms. I returned the parameters back to stock (I have 20" rims, but retained close to the factory circumference of the tires) & like magic, all was well.

 

You'd either need a Tech II scan tool ($$$$$$$$), or another set of OEM wheels ($$$) to make this go away I think.

[nicholsyukon12]

i have appt with yet another mechanic thurs morning , sure hope these people will know what to do, and really hope it doesn't cost toooo much lol

 

thanks for the replies

[88m53453]

Had a trans shop working on my trans a while back,same sort of crazy myriad of problems, they messed up the wires going to the speedo pickup on the tail shaft housing. I sat in their waiting room and figured it out . It rang a bell from my tech days and working on imports. Quick search on my tablet and viola...went outside, crawled under my own dang truck and fixed it while they were sitting around coffee trying to figure it out....