From digest.v7.n1019 Mon Jan 26 10:22:31 1998
From: "Alan Alfano"<Alan.Alfano_at_SNET.com>
Date: Mon, 26 Jan 1998 07:34:26 -0400
Subject: Re: E30 ABS analysis [long]

In v07.n1001, From: Paul Cuaresma <cuaresm_at_hawaii.edu> >I am having problems with my ABS system on my 325i. The ABS malfunctions
>everytime I turn the car on now.

In v07.n1006, From: Christopher Pawlowicz <chrisp_at_doe.carleton.ca> reposted previous posting from: Kenn(y)(eth) Sebesta, in summary Ken suggested to:

>1) Check the ABS wheel sensors.
>2) Check the ABS relays
>3) Check the instrument cluster ABS lightbulb for the system.
>4) Check the ABS pump.

Paul,
Sorry to be running a little late with my response.. In addition to Ken's checklist, you may want to consider trying the following ABS checks:

1. Incorrect Jump Starting If one incorrectly reverses the connections (even momentarily), a relay attached near the top ABS control unit which is located under the dash, left of the steering wheel will get toasted. Discount parts vendors sell this for approximately $21.
2. Intermittent ABS Warning Light The ABS warning light may come on intermittently, and normal troubleshooting procedures do not indicate any defect. This can happen when the vehicle is driven over 50 mph, or on cars that have recently had two new tires, or snow tires installed.Check all four tires on the car to make sure they are all the same brand, style, and size. Also note if there are any new tires with substantially more tread than the other tires. Differences in tires may cause enough variance in rolling diameters to confuse the ABS control unit, which may give a false signal to the ABS warning light. This is especially true if snow tires have been mounted on the rear wheels only.
3. ABS Wheel sensors Some 3 Series vehicles may experience a situation in which, during braking, the ABS will activate even though the brake application is light and traction is good. This may be caused by the pulse ring being loose on either front wheel hub, which allows the pulse ring to rotate, sending a false input to the ABS control unit. If this condition is found, replace the front wheel hub with the loose ring.
4. ABS Sensor Lead Faults If a problem was encountered in an ABS Sensor Lead, the repair is replacement of the vehicle main harness. Separate leads are now available that allow individual replacement of each of the 4 separate sensor leads. In most cases a fault in a sensor lead will show up as an intermittent fault (ABS warning lamp comes on while driving). These sensor leads are available under the following part numbers. (One lead and the necessary connectors for the repair are included in each package) Sensor lead E32/E34 - P/N 61 13 9 061 686 Sensor lead E30 - P/N 61 13 9 061 687

I hope this is of some help,
Alan Alfano
alan.alfano_at_snet.com

BMW CCA #30492

1988 BMW 325iX
1956 Austin-Healey 100M (2)