Abs Light

[acerche]

Hey,
I have a 325ic 1995 model. The ABS light is constantly on. I took it to BMW, they ran the diagnostic and it spat out "code 81 - front left wheel sensor." They changed the left and right front wheel sensors over and it still spat out the same "code 81 - front left wheel sensor." Their conclusion: the ABS controller unit needs to be replaced for $1000. This is 1/10 the value of the car to turn off the ABS light!!! Could they be wrong? Any ideas?

Interestingly, the ABS light came on after driving in heavy rain and large puddles. Could this be related?

[DesmoBob]

does the light come one and stay on when you start the car? or only when you start rolling? after they did the swap (left to right), did they actually drive it around, or did they just start the car and look at the lights and re-read the codes?

if it only comes on after you start moving, it is likely a sensor, because it is signaling a discrepancy in the speed readings among the individual wheels. otherwise, you might consider a second opinion from an independent bmw mechanic (note: independent mechanic can charge you $100 and up just for a diagnosis).

btw, verify what they mean by controller unit. i have heard the same term used for two different components. some people use the term "controller unit" when referring to the actual abs computer, but others use "controller unit" when referring to the hydraulic unit (aka the hydro). a source of confusion there down the line.

if it's the hydro, it CAN be repaired diy (although for liability, bmw or any other mechanic will not do it, and recommend a whole new unit).

if it's the computer, then yes, $1000 sounds about right, although i thought they went for much higher than that.

[acerche]

Originally posted by DesmoBob@Apr 7 2005, 03:40 PM
does the light come one and stay on when you start the car? or only when you start rolling? after they did the swap (left to right), did they actually drive it around, or did they just start the car and look at the lights and re-read the codes?

if it only comes on after you start moving, it is likely a sensor, because it is signaling a discrepancy in the speed readings among the individual wheels. otherwise, you might consider a second opinion from an independent bmw mechanic (note: independent mechanic can charge you $100 and up just for a diagnosis).

btw, verify what they mean by controller unit. i have heard the same term used for two different components. some people use the term "controller unit" when referring to the actual abs computer, but others use "controller unit" when referring to the hydraulic unit (aka the hydro). a source of confusion there down the line.

if it's the hydro, it CAN be repaired diy (although for liability, bmw or any other mechanic will not do it, and recommend a whole new unit).

if it's the computer, then yes, $1000 sounds about right, although i thought they went for much higher than that.

[snapback]327869[/snapback]

it comes on when I start the car. they did not drive it after swapping the sensors. controller unit = actual abs computer.