Chapter 27: MindTap

ammeter

A CKP sensor can be checked with all of the following except a(n) ___. - logic probe - voltmeter - ammeter - lab scope

False

T/F: Coil secondary resistance is typically very low, less than 1 ohm.

True

T/F: On some engines, if the gap between the crankshaft sensor and its trigger wheel is outside specifications, the sensor should be replaced.

False

T/F: The first test when checking a no-start condition is to check all input signals.

Both

Technician A says that EMI can affect sensor signals. Technician B says that EMI can cause intermittent driveability problems. Who is correct?

Tech A

The firing lines on an oscilloscope pattern are all abnormally low. Technician A says that the problem is probably low coil output. Technician B says that the problem could be an overly lean air-fuel mixture. Who is correct?

all of the above

Which of the following will cause one or more, but not all, firing lines to be higher than normal? - high resistance in the spark plug wire - faulty fuel injector - defective spark plug - all of the above

Shorted

While checking a pickup coil with an ohmmeter, a lower-than-normal reading indicates that the pickup unit is ___. - Shorted - Open - Has high resistance - none of the above

Tech B

While discussing EI service and diagnosis: Technician A says that the crankshaft sensor may be rotated to adjust the basic ignition timing. Technician B says that the crankshaft sensor may be moved to adjust the clearance between the sensor and the rotating blades on some EI systems. Who is correct?

Tech A

While discussing engine misfire diagnosis: Technician A says that a defective EI coil may cause cylinder misfiring. Technician B says that a shorted CKP could cause a misfire. Who is correct?

Both

While discussing how to test a Hall-effect crankshaft position sensor: Technician A says that a logic probe can be used. Technician B says that a DMM can be used. Who is correct?

Tech A

While discussing no-start diagnosis with a test spark plug: Technician A says that if a test light flutters at the coil tach terminal but the test spark plug does not fire when connected from the coil secondary wire to ground with the engine cranking, the ignition coil is defective. Technician B says that if a test spark plug connected to a terminal of a waste spark ignition coil fires when the engine is cranking but the engine does not run, a bad PCM is indicated. Who is correct?

Both

While discussing the diagnosis of an electronic ignition (EI) system in which the crankshaft and camshaft sensor tests are satisfactory, but a test spark plug connected from the spark plug wires to ground does not fire: Technician A says that the coil assembly may be defective. Technician B says that the PCM may be faulty. Who is correct?

Tech A

While discussing the possible causes for a no-start condition on an EI-equipped engine: Technician A says that a shorted crankshaft sensor may prevent the engine from starting. Technician B says that a faulty ignition coil may stop the engine from starting. Who is correct?

Both

While discussing waste spark EI systems: Technician A says that a spark plug with too wide of a gap can affect the firing of its companion spark plug. Technician B says that improper spark plug torque can cause an engine misfire. Who is correct?

Tech B

While testing the coils in an EI system: Technician A says that an infinite reading means that the winding has zero resistance and is shorted. Technician B says that the primary windings in each coil should be checked for shorts to ground. Who is correct?

Richer

Will richer or leaner air-fuel mixture decrease the electrical resistance inside the cylinder and decrease the required firing voltage?