I have a 2002 pontiac grand prix everytime i turn left my speedometer quits working and it starts downshifting due to that.. i have replaced both front wheel bearings and the speed sensor.. what am i missing??

Have you checked to see if the lines are getting clipped by something when turning?

I have cked but couldnt find anything

Is the ABS light or the traction control light on? If so is it one or both ? Are they on at the same time ? If so is one or the other is on is it always on or just random? Or has either light came on at all?

Edited March 7, 20179 yr by TWO LANE BLACK TOP

Neither light comes on.. runs great other than this issue

When you replaced speed sensors did you replace both sides or just drivers side?

Also have looked for anything that might not look right at the rear wheels too? Reason I ask is could possibly be any of the wheels as each wheel rotates when turning left all 4 of the wheels are rotating at a different speed might not problem be with just the front wheel sensors at all very possibly could be in rear. When car is travelling straight all the wheels are turning pretty much the same RPM when turning each individual wheel turns at different RPM and then they are all integrated together VIA abs module.

Edited March 7, 20179 yr by TWO LANE BLACK TOP

I replaced the one on passenger side i didnt know it had two on there

There is speed sensor on each wheel front and rear. A total of  4 sensors are on the car Hence 4 channel ABS Before you go spending money on parts Do a thorough inspection of speed sensors on each individual wheel front and rear. Look for damaged wires connections corrosion etc. Also if you know someone or have access to a quality scanner plug into diagnostic port .Sometimes the ABS module will hold a hard numerical code that will not show on the ABS or traction control lights. It is completely separate system than the PCM . A lot of cheaper scanners or code readers Like from auto parts stores do not have capability to read ABS codes but some do. Anyway come up with one that does plug it in and see if has stored code in ABS module then go from there. Possible speed sensors could NOT be problem at all. Hope this helps.

Edited March 8, 20179 yr by TWO LANE BLACK TOP

Sorry for your problem, but wheel sensors won't cause this problem! I can't go in to detail right now, but I'll explain tomorrow.

Sorry i meant transmission speed sensor.. i changed it and both wheel bearings on front which have the abs sensors in them.. i appreciate all the help guys!! Ooh and whats weird is it only does it while vehicle is on the ground if i raise both front tires off the ground i can go as fast as i want and turn the wheel to the left and it doesnt do it

Ooh and i have a scanner that does abs but it wont connect for some reason.. it connects fine to ck engine codes but not abs!!

OK completely misunderstood sorry about that. thought you were talking about wheel speed sensors. Feel like a complete dumb*** any way never mind all the things I said about ABS and speed sensors. Except part about Might not be the problem. actually probably some sort of transaxle issue. Do not really know what that may be. Some sort of fluid level issue or with the little check balls in the valve body? something filter related? differential maybe?  Wondering about it myself will ask my transmission guru friend when see him tomorrow.

 

Edited March 8, 20179 yr by TWO LANE BLACK TOP

I thougjt that too but it only does it when u turn left.. doesnt matter if your going 5 mph or 55 mph.. like i can go in circles in my yard and the speedometer wont budge until i turn steering wheel back to the right.. its crazy lol.. 

Last indian  may have the answer wont know until tomorrow. Will ask my transmission guru tomorrow also.. Hopefully will be able to get it solved in short order.....

I really hope so... i really appreciate everyones help.. i did notice on my way home from work that even going straight the rpm gauge and speedometer was jumping a little bit.. not sure if it was cause of bumps in the road or what..

2020, if I may, first off wheel sensors if the don’t work simply revert to a dormant mode, I.E. no abs & no traction control. So they are a non issue under all circumstances. The downshifting issue is another story! It is definitely electronic, but without looking at a schematic I can’t say what. That will take a little time, I have all the manuals, I just have to go see what interfaces with what. In the mean time you can look at another possibility. While it may be a slim one, I’ve mentioned this before, that these platforms are are wired with five 12 volt leads. They feed the ignition switch which is a series of finger switches that distribute power to the rest of the car. It is very common for these finger switches to burn and when they do they no longer deliver 12 volts. This in turn causes electrical issues with whatever branch is on that 12 volt lead. As of now I don't know how, if at all the tac ties into the equation. So try two things, first go down on the steering column and find the plug coming out of the ignition switch. Locate the 12 volt supplies at the plug. Using a volt meter, with the key on, get in to the backside of the wire were it inserts into the plug and see if you get 12 volts. Do this for each 12 volt lead. The other, and you may wish to do this first is disconnect the traction control at the source, not the switch. 

Ok im looking into this right now i will let u know what i find.. thanks

I have 12 volts on all them except the yellow wire it has nothing.. and the orange wire is only getting 11 volts

Hey what do u mean disconnect from source? I dont see a fuse for traction control anywhere

Ok with car running i have 13v on all the wires except yellow one it still shows nothing... i pulled abs fuse incase it was tied in with trac control and same issue

I have crawled all over this thing looking for loose wire or broke wire.. i have found nothing so far.. i need a miracle lol

Do you know if you have cruise control? It appears the yellow wire feeds the cruise & the cruise & trac control are tied together. Because all traction control does is low rpms. So possibly it's one of two things, 12 volt power to yellow or a ground issue. See if you have cruise, then pull the cruise fuse and also check your ground connections. If that's not it…. Well we’ll keep thinking.

Spoke to my trans guru Today. He agrees with Last indian that is definitely an electronic issue. Without actually looking at the car would be probably next to impossible to trouble shoot....Wish I could be more help. From I have seen looks like last indian is a smart guy and is all over it. He has my compliments.

Edited March 8, 20179 yr by TWO LANE BLACK TOP

You ahve helped alot and i appreciate it.. i dont know what else to do lol.. ive tried everything i know to do i hope someone can figure it out lol

So your saying you have cruise control?