Thread: Brakes: 850: - Should my car have ABS?
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Old Apr 15th, 2021, 13:48   #23
JohnM 855 T5R
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Quote:
Originally Posted by tony209 View Post
You might just have split reluctor rings, the left front failed on my C70 with no ABS warning light and now the other side has gone - again, no ABS light. The system check only tell you that all the connected parts are communicating correctly. If you have cruise control, this won't work if you have a damaged reluctor ring.
Our beloved old Volvo's often have a mind of their own and you may be right, but I can say the following:

1) The diagnostic manual says the ABS light should light up and stay lit if there is either no signal or an incorrect signal from any of the wheels sensors when moving. Obviously, at start up, the ABS light goes out if all is well before moving off as the system checks communication between each component. Before moving off, the reluctors aren't generating a sensor signal. When running, faulty reluctors will light up the ABS light. When the ignition is switched off, the ABS light resets to off and will come on again next time the fault is detected.

2) My stepsons 1998 C70 coupe had the ABS light come up - cause was the reluctor teeth had corroded away (hardly surprising at 400,000 miles). This would confirm that the first point is correct.

Mind you, I'm the first to admit that the diagnostics on 850's and C/V/S 70's can be a bit hit and miss.

Regards
John
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