Expert: Sean Halliday - 4/15/2008

Question
QUESTION: This car had an idle problem, now it won't start. No spark or injection pulses. reference sensor checks out but speed sensor show open circuit. Can this be the cause of a no start.

Thanks

ANSWER: No,the speed sensor will not cause this but you might want to check the crankshaft sensor.Also the distributor and cap.There are a few reasons for no spark so you will have to go through the procedure of eliminating the electrical causes.Crank sensor,cap,rotor,wires,coil,make sure the timing belt is ok and set at the correct timing,and the ignition module.Haynes manual will help you and they are easy to get online or ebay for $10 or less.

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QUESTION: The crank sensor, according to Hanes, is used only for diagnostic. There are 2 sensor on the bellhousing, one is a speed sensor the other a reference sensor. The speed sensor doesn't have any resistance on any pin combination. According to the manual they should have the same readings.

Answer
If the sensor is not reading as per spec,replace the sensor.Thats a start,but have you eliminated all other possibilities?What other codes have came up?I have never seen a crank sensor used for diagnostics as it is used to pick up electrical/magnetic impulse as the crankshaft turns.On this car,it is used to time the fuel injectors.Your distributor generates the spark.The speed sensor is for the speedometer/transmission changes.