One type of question asked on many ASE tests is a question that asks which of the following is least likely to be the cause of a problem or symptom. In other words, all of the answers are possible, but it is up to you to decide which answer is the least likely to be correct. Make sure to read the question and answers carefully before selecting an answer. Let’s try one of those questions now.
Which is the least likely to cause a weak spark at the spark plug?
A: A partially shorted primary winding in the ignition coil
B: A high-resistance spark plug wire(s)
C: A 12.2-volt battery voltage
D: A voltage drop across the ignition switch
The correct answer is C. The least likely cause of a weak spark is a battery voltage of 12.2 Volts. Even though the battery voltage is less than normal, it should be enough to allow the ignition coil (s) to become fully saturated and provide the correct spark to the spark plugs. Answer A is not correct because a partially shorted primary winding of the ignition coil could cause a weak spark and the question asks for which is the least likely to cause a weak spark. Answer B is not correct because a spark plug wire with high resistance could cause a weak spark. Answer D is not correct because a voltage drop across the ignition switch would reduce the current flow to the coil which could cause a weak spark.
This video is sponsored by Autolite.