Hiya Uncle Old Duke,

Sorry for my tardy reply.

Is the ABS light on at time of start or as you begin moving the 245?

With ABS light on, you do not have operating ABS.

I'll guess you have your answers here. Though you indicated ABS and CHECK ENGINE (oxygen sensor fault code[s]) illuminated on your instrument cluster in prior posts.

You have already performed OBD-1 check of socket 2 (fuel injection) and 6 (ignition). ABS-unrelated though.

You can remove, clean, and replace the two ABS sensors at each wheel. The task is made easy or difficult by how much crud is between the front wheel ABS sensor barrel in spite of the o-ring in grooves at the sensor barrel. The o-rings by now, and I guess two or three of them, are probably a little swollen and do not seat tightly in the grooves, making removal and reinstall after cleaning sometimes difficult.

You use a Torx or (?) Allen wrench key on the single machine screw head that secures the front wheel sensor to the hub. Twist, spray some kind of non-persistent lube or maybe even brake parts cleaner (chlorinated or non-chlorinated - whatever is less caustic to the plastic and o-ring bits). Also, with same brake parts cleaner, spray the sensor hole clean. Wipe down the sensors with some of the cleaner and havy shop paper towel or some such. Some of that brake parts cleaner can help with reinstall as a residue-free lube. Twist in. A good hand will force the o-ring back into the grove prior to slipping into the bore.

The Volvo factory green manual for 240 ABS lists what causes the ABS Control Unit to illuminate.

Yet the ABS Controller, usually, is concerned with continuity of the two front connected devices, connection to ground, and power. I believe there is a ABS Controller check of connection of the ABS modulator or pump.

You have the two connectors along the inner fender between the ABS wire harness to the controller. In a prior thread on your ABS light, you use a conductive metallic-particle paste to prevent future corrosion. I would have used a dielectric grease like DeoxIT-D or SuperLube brand silicon grease (my preference for the NLGI 2 version).

You also have the ABS system wire harness connector at the ABS Control unit. Corrosion can form here. More so is you have water intruding into the front area of the passenger compartment, passenger side. ABS Control unit is under the passenger seat. Or the driver seat? I'm unsure now. An inspect may reveal, as Art posted images of some time ago, a rusted ABS Control unit housing. My hope, after you disconnect the battery, is a quick disconnect / reconnect of the connector housing. Some dielectric grease like DeoxIT-D or SuperLube brand silicon grease at the connector and pin side helps with low volt DC.

Do not use conductive grease with metallic particles in any connector. Or on the fuse panel, or the tail lights ....

The other part of the ABS is the Transient Surge Protector, a relay-10 amp fuse assembly. The ATC fuse can fail, or have corrosion, or if passenger compartment moisture intrusion, form rust on the housing and, like the moisture encountering ABS Controller, rust.

The ABS Controller connects directly to the differential mounted speedo sensor as does your instrument cluster. If your speedo works, the issue may connection at the ABS Controller. It's been 10 years since I dug around with dash and seat removed in my great 2008 1992 Volvo 240 GL sedan windshield rust repair and replace. Never did I screw up a windshield install before. Even had the two Volvo butyl tape rolls. So I dunno where what is.

Here is a partial diagram. Shows nothing under the seats. Or the seats. From the green manual.

Also, what color is the brake fluid?

196 maybe the ABS Controller, mounted on the bulkhead, under the dash, on 1993?
200 is the relay / 10 AMP ATC fuse transient surge protector?

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You could try all of the OBD ports and see if you get any fault codes. The A-1 is normally the transmission, the A-2 is engine, and A-3 should be the ABS. At least that is for the 940, same year. You insert the probe in one of the holes, and with the key in position II, press the little black button in the box for about 1 second - the red light will glow when you do this. The system then responds with a blink of the red light. Count the flashes, 1 through 9. There will be a slight pause between each number with each code being 3 numbers in total. A result of 1-1-1 indicates no codes present.



No, the OBD is not for dealer rip off. It helps them to narrow the search for the problem.

As for cleaning the sensor rings, yes, but do NOT use compressed air!! That is super fine particles and can lodge in the lungs. I would use a spray bottle and wash the sensor rings, or use a shop vac. It can get crusty.

Also check the sensors themselves, make sure they are pointing toward the ring and the wiring is not compromised.

An ABS malfunction will not have any affect on your breaking ability, it is only there to prevent brake lock up.
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Keeping it running is better than buying new

I believe Kitty is correct. No fault detection codes for ABS in your 240’s OBD1 system. Your car does in fact have OBD1 but a very basic version. So, I guess what you have is a red ABS fault light on your dash, correct?

Try cleaning the ABS sensors of rust, grime etc. Many old posts here on that topic. That often cures the problem.
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Will I buy another Volvo??? We'll see....