bad sensor? which one?

From : dennyandy

Q: on sun 02 nov 2003 043010 gmt roy roy@home.net wrote how is the candy g roy they have candy coated carrots *lmao* hey mac to quote a line out of my all time favorite movie do the letters fo mean anything to you vbg if they have carrot cake they can make candy carrots!! denny .

Replies:

From : speed

speaking of the speed sensor. my abs and break warning lights went on. i took the truck in 98 dakota and i was told the speed sensor was bad which seems really odd... if that was the problem it fixed the problem just me 2 cents on a speed sensor. .

From : tom lawrence

speaking of the speed sensor. my abs and break warning lights went on. i took the truck in 98 dakota and i was told the speed sensor was bad which seems really odd... if that was the problem it fixed the problem not odd at all. we call it a vehicle speed sensor but its primary job is in sensing the rear wheel speed in relation to the front wheels. the sensor simply sends a pulse of electricity several times for every revolution of the rear axle. the front wheel speed sensors do the same. the abs computer compares these results and thats how it knows if a wheel is locked up skidding and it can do what it needs to do to correct that. however if it senses a discrepancy beyond a certain built-in tolerance between the sensors with the brake not applied it sets off the warning lights. now - the pulses themselves mean nothing in terms of vehicle speed - they simply indicate to the abs computer the relative speed of all the wheels. the abs computer passes the pulses from the rear wheel sensor to the powertrain control module which is programmed to say well it appears the axle is turning 300 times per minute. since i know this truck has 31 tall tires that means.... 31 times pi times 300 divided by 1056... the vehicles moving about 27.5mph. so the vehicles speed is interpreted by the pcm based on the input from the rear wheel speed sensor but the sensors primary function is part of the anti-lock braking system. .