Speedo lost - ABS & ASC lights on - BMW Forum

arh · 06-18-2007, 06:35 AM

Problem on my 1999 523i.

Both my ABS and ASC lights come on intermittently. It seems to happen when I have driven for 30 mins or more but it can be random. Speedo and MPG is also lost when these lights are on. It I switch the car off (when lights are on) and turn it back on the problem does not clear. Cruise control works all the time even when lights are on.

I've been reading that is either the abs sensor cable or the abs unit. What is the easiest way that I can diagnose? Is it easy to swap the to sensor cables over. How can I test the abs unit?

Thanks.

PhilH · 06-18-2007, 08:43 AM

easiest way must be to have it connected to the computer.

arh · 07-20-2007, 05:15 PM

Update:
Went to BMW specialist who diagnosed problem with ABS unit. Computer diagnostics showed left rear sensor but changing this did not clear the fault.

Sent my unit to ecu-testing.com for repair and it came back today (cost £250

)

- put repaired unit back into car and now both ABS and ACS lights come on straightaway. The ABS unit also makes a load noise when checking the system when the car is started! I'm sure that it was not as loud before repair...

Please help... will contact repair company for advice tomorrow and give update.

arh · 07-21-2007, 02:43 PM

Panic is over as problem is resolved as both ABS and ASC lights are off and speedo is fine even after a long trip. I did read on another formum that once the ABS unit has been repaired it an take a little while to settle down. Mine seemed to be ok after the second time I drove the car.