The Volvo 240 is an OBD-1 car. No scanner connects to any of the control modules for fuel injection, ignition, and the anti-lock brake system.

Uncle KlausC is correct there is an OBD code reader box not requiring a scanner on the driver side inner fender between the brake vacuum booster and the hood hinge. Merely connect the lead to the socket. Volvo 240 with Bosch LH-2.4 Jetronic injection and newer have this box and you can check for fuel (socket 2) and ignition (socket 6). No connection to the SRS system here, tho that I've seen. Your 1993 240 may have a socket on that box to connect the test lead to a socket other than 2 or 6. Not sure. the Blue Bentley Volvo 240 Bible may help you. The Haynes won't other than a brief and simple discussion of ABS on the 240.

Please see the FAQ here at http://www.brickboard.com/FAQ/700-900/BrakesABS.htm

This info may not accurately reflect on your 1993 240. Hopefully it'll help you.

Uncle jwalker is right in that the ABS sensors at both front wheels can collect a build up of metal dust rendering the front wheel ABS sensors less and less effective. Various methods exist in cleaning them. You may be able to remove them from the hub assembly from the backside of the the hub assembly, merely wipe off with a shop rag and perhaps a little brake parts clean or other residue-free safe solvent. Also, check the connectors that run from the ABS front wheel sensors to the cables they connect to. You can use a multimeter at this point and verify the sensors are not faulty by using a ohmmeter or continuity meter. The front wheel ABS sensors merely contain copper field coil winding to generate an electrical impulse when the hub tone ring, with built in magnetic load(s), passes the senor to the ABS computer. The front wheel ABS sensor can begin to possess a small magnetic gauss field themselves over time rendering them less effective, also. (Why ferrous metal dust can collect and adhere to the sensor housing.)

The rear axle ABS wheel sensor is one in the same as the speedometer sensor mounted on the rear plate of the differential pumpkin (housing).

A fault could exist in the ABS pump, mounted behind the battery, if the brake fluid is very old and black. Never let the brake fluid become darker than a dark tan and opaque. Always replace the brake fluid with new every two years.

Hope that helps.

cheers,

Buttermilk MacDuff.
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Someday, we can use the gravity well beneath all of us to power mechanical action to generate electricity pollution free.