Rear Antilock
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Joined: Oct 2003
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From: The Hammer
Rear Antilock
hey, kinda new to the scene..
just wanna know if its bad for my REAR ANTILOCK light to come on, it used to stay on all the time, now its everyonce in a while, just wanna know why..
1990 XLT
just wanna know if its bad for my REAR ANTILOCK light to come on, it used to stay on all the time, now its everyonce in a while, just wanna know why..
1990 XLT
Postmaster
Joined: Apr 2001
Posts: 3,818
Likes: 3
When the warning light comes on, the rear anti-lock feature is disabled but the brake system is still functional - works just like all cars did before the advent of anti-lock.
As to why, that is always a mystery. Sensors feed data to a control unit which in turn modulates a dual valve assembly. There are a variety of reasons why a light comes on. If yours has only the RABS yellow light and not the red BRAKE light, it is likely a detected difference between the two speed sensors - one on the transmission and another at the rear differential. Sometimes just low tire pressure on one side is sufficient to trip the sensor.
Another problem source is the valve assembly. As time goes by, the seats and stems suffer mild corrosion from moisture in the brake fluid. On engine start up, the valve assembly is briefly activated as part of the systems check. Occasionally one of the valves sticks open/closed and this trips the error code.
You can spend hours chasing these gremlins down. If the light is only on intermittently I would just leave well enough alone for now. When it becomes a continuous signal, that would be the time to delve more deeply into the cause.
As to why, that is always a mystery. Sensors feed data to a control unit which in turn modulates a dual valve assembly. There are a variety of reasons why a light comes on. If yours has only the RABS yellow light and not the red BRAKE light, it is likely a detected difference between the two speed sensors - one on the transmission and another at the rear differential. Sometimes just low tire pressure on one side is sufficient to trip the sensor.
Another problem source is the valve assembly. As time goes by, the seats and stems suffer mild corrosion from moisture in the brake fluid. On engine start up, the valve assembly is briefly activated as part of the systems check. Occasionally one of the valves sticks open/closed and this trips the error code.
You can spend hours chasing these gremlins down. If the light is only on intermittently I would just leave well enough alone for now. When it becomes a continuous signal, that would be the time to delve more deeply into the cause.
