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gone4nm 5/31/2013

1991 Lexus LS400 Base 8 Cyl 4.00L


car vibrates when i step on the brakes, light comes on that says TRAC off

1 Answer


Jimm 6/1/2013

If the warning light 'TRAC' is on - this usually indicates there is a fault with the traction control system - usually wheel speed sensors - since they are in a hazardous location, but I would also expect an ABS error light to come on if one has failed.
I would look at things like the secondary throttle motor and TPS as these are TRAC only items. Most of the other signals used by TRAC also tell the engine ECU and ABS systems something like vehice speed, throttle input, brake status, etc. If the brakes vibrate when applied, then you may suspect the following; ABS sensor, wheel speed sensor. Have the OBD system scanned for any stored fault codes (for free - at any local auto parts store). There should be an error code stored for TRAC. If not, maybe your trac-off button is acting up.


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