ASC Light always on asc not working?? - BMW Forum

masesE39 · 12-06-2008, 11:28 PM

i went out to my 98 540i the other day and when i started it the ASC light was no and i couldn't turn the ASC on the switch was not turning the ASC on and off
does anyone have any info on this i live in ohio and its about time that we get a lot of snow and i would love to have my ASC working help please!!!

witeshark · 12-06-2008, 11:35 PM

It may be as simple as a brake fluid service (change), like with ABS brakes.

AlpineSixAndSeven · 12-06-2008, 11:50 PM

usually it is the wheel speed sensors have the codes read then i can help better!

masesE39 · 12-07-2008, 12:00 PM

but there is no abs light or brake light on?? so i didn't think that it could be a wheel speed sensor???

AlpineSixAndSeven · 12-07-2008, 04:21 PM

hmmm... should still have some kind of error code.... unless the button is stuck and always turning it off??? could be a bad ASC controller...

masesE39 · 12-07-2008, 06:09 PM

do you know how to take out the asc button so i can test the switch for continuity when pessed in and out??? i have and xm radio and i had it sitting in front of the button i wonder if the xm unit was pressing against the button all the time frying the switch??

masesE39 · 12-08-2008, 10:39 PM

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do you know how to take out the asc button so i can test the switch for continuity when pessed in and out??? i have and xm radio and i had it sitting in front of the button i wonder if the xm unit was pressing against the button all the time frying the switch??

AlpineSixAndSeven · 12-09-2008, 12:38 AM

^???? ummmmmm ok then.....

The button just pops right out just Gently pry it out....

masesE39 · 12-09-2008, 08:35 AM

o ok thought you might have to take out middle console to get to it thanks!! i will give it a shot and see what happens i hope its the switch and not the asc control

masesE39 · 12-10-2008, 11:00 PM

As i was looking at the prethrottle cable and motor the cable attaches to it. I found the problem, the cable was in place but the cable was broke where you couldnt see it. I didnt see it until i turn the throttle plate by hand and the cable didnt return to fixed position. I then pulled on the cable when it slid right out of the casing witch goes to the motor. so bingo!! new cable $ 12.80 loved it...lol also the code was 39 38 for the prethrottle not opening and closing.
If anyone has same prob with asc light on ONLY!!! check for this. you will also notice lost in power even with asc turned off and worse gas mileage. Thanks Every one for the help!!

witeshark · 12-10-2008, 11:11 PM

Glad to see you found your answer!

mrmojo37 · 12-11-2008, 08:10 AM

My ASC light stays on. My gas milage is poor. I have a 1997 528i. What exactly is a pre-throttle cable and what does it do?

masesE39 · 12-11-2008, 09:19 AM

well the pre-throttle is a throttle body that is connected to your intake tube. you have two in our case because of the traction control. one witch is after the airbox and one that blots to the intake manifold.The first one is your pre-throttle. It controls rpm and air intake to the eingne to help the traction control work. so if the cable is broke and the throttle plate is stuck in one position the asc system will see this and shut down the hole system and turning your asc light on all the time. The cable runs from the first throttle body to the right side of the engine bay if you looking at the engine!! if you turn the throttle plate by using the throttle linkage and the cable does return to being straight and it stays looped up by linkage try pulling cable out of sleeve if its broke on either side you will notice when you pull on it or when you open the throttle plate. Hope this gives you some idea how it works and where it is. let me know if you have anymore questions and good luck

mybeamer · 12-19-2008, 08:01 PM

hey i have the same problem. i pulled the cable and cant find the other end. where is the motor that the cable hooks up 2. i looked under the booster and the abs unit and the master cylinder and cant find it. even my boss cant find it. i work in a shop and im going to look again tomorrow. please help. by the way my car is a 94 530 i. thank you

masesE39 · 12-21-2008, 10:42 PM

well i am not sure since you have a 94 and mine is a 98 540 but my motor is on the right side almost on the wheel well there is the cruise control motor and bolted to the front of that motor is the motor for the pre throttle body..... I hope this helps let me know??