ABS light

[hitmachine101]

Hey guys, have a friend that just picked up a 95 M3, its been on ever since he got it and its starting to frustrate him, he knows that the break resovor is full and the breaking system itself is not of suspect. tell s me it breaks great.

I ve heard that there are sensors in the pas rear and driver front but thats about it refering to the matter -- what do you guys think could be the problem?????

[Jeron]

The pass rear and Drivers front sensors are pad wear sensors and not related.

There are wheel speed sensors on each wheel hub and they are a common cause. You could remove, inspect and clean them.

Likely he will need to take it to a BMW mechanic and have the ABS codes read.

[hitmachine101]

ok we located all 4 of them -- one on each hub like you said -- now how do we test them -- can we hook a volt o meter to the plug and spin the tire??

if not -- should we just plug and play? theres a parts car availble for us to do that with -- if thats what we should do then will light go off instantly when we get the right one or will we have to pull the battery terminal off???? drive it for 5 miles or something????

[Jeron]

Do a internet search for testing wheel speed sensors and you should get the info you need.

I am not sure what will make the light go off, but pulling the battery and touching the cables together should reset everything.

[hitmachine101]

ok well we got some info from an internet search or two but our next question is where do all those sensors lead to? -- there has to be a central brain for all that -- and is it possible that it went bad??

thanks guys

[hitmachine101]

helping my friend go after his main ABS unit -- presumably under the dash or pasenger dash -- kinda plan to plug and go here guys -- i ve tried the internet search but theres nothing about what to expect when i actually might change the right thing -- will the light go off imeadiatly???? does it stay on untill i pull the battery terminal and wait 25 min??? if i end up pulling wheel sensors and testing them do i spin the tire a certain speed to generate the desired output of voltage for the sensors?????

anyone who has gone after an ABS light before please let me know -- this has been causing a very large headach for my friend and these cars are susposed to be fun

[hitmachine101]

cleaned all the wheel sensors and still a check engine light -- i pulled the battery ternamal as well and still there -- my friend really doesnt want to bring it to a bmw mechanic because we have the parts and what not to mis and match sensors -- his only problem is that he doesnt know which one(s) are dead and or working -- really wishing there was a tool to plug in and tell us which one was bad -- anything like that out there or is he just going to have to throw in the towel and bring it to BMW to get it fixed???

[hitmachine101]

im sorry not a check engine light, an abs light

[Jeron]

I dont know any way to get diagnostic from the ABS system. A mechanic with the proper test computer will be able to check it though.