This article will help you to troubleshoot and diagnose a BAD crankshaft position sensor on your 4.3L, 5.0L and 5.7L Vortec equipped GM Pick Up or SUV.
Since the 3-wire crankshaft position (CKP) sensor can not be tested by a multimeter resistance test (Ohms), I've written this article to show you how to do it with just a multimeter in Volts DC mode. This is a very accurate and effective test and will help you to know if it's good or BAD.
Since this crankshaft position sensor test article covers quite a few GM years, makes and models, take a look at the ‘Applies To:’ box on the right and scroll with the ‘Next > >’ button to see all of the applications. Also, the info in this article is geared towards diagnosing and troubleshooting a Cranks But Does Not Start Condition - No Start No Spark Condition.
Here are the contents of this article at a quick glance:
You can find this tutorial in Spanish here: Cómo Probar el Sensor de la Posición del Cigüeñal (P0336, P0337, P0338, P0339) (at: autotecnico-online.com).
Suggestion 1: The crank sensor test I'm gonna' show you in this article, is one of the most accurate ways to test the crank sensor without an oscilloscope (and using only a multimeter) only if you turn the engine by hand. You'll need to use a 1/2 ratchet wrench and the appropriate socket to turn the crankshaft pulley.
Suggestion 2: It's very important that the Spider's fuel injector's connector be disconnected while performing the crankshaft position sensor test. Unplugging this connector will disable the computer from injecting fuel into the engine.
You don't need any expensive tools to test the crank sensor on your 4.3L, 5.0L, 5.7L engine.
Tools You'll Need:
The most common symptom of a BAD crank sensor is a ‘Cranks but Does Not Start Condition’. In other words, your GM vehicle will crank over when you turn the key to the Start Position but will not start. Below is a simple list of more specific symptoms that accompany a BAD crank sensor:
The most important thing to remember, is that if you get spark from any spark plug wire, the crank sensor is working and the test in this article won't help you. If this is the case, in your particular case, the following tutorial may be of help:
“This planet has - or rather had - a problem, which was this: most of the people living
on it were unhappy for pretty much of the time. Many solutions were
suggested for this problem, but most of these were largely concerned
with the movement of small green pieces of paper, which was odd
because on the whole it wasn't the small green
pieces of paper that were unhappy!”
The Hitchhiker's Guide to the Galaxy