If the crank sensor fails, in your 4.8L, 5.3L or 6.0L GM vehicle... it's not gonna' start. In this article, I'll show you how to test it using a multimeter (in Volts DC mode).
The crank sensor test in this article is an On Car Test. It's not possible to do a simple resistance test of the crank sensor. Why? Well, it's because this crank sensor is a Hall Effect type and these can not be ohmed (to find out if they're good or not).
Here are the contents of this article at a quick glance:
TIP 1: To perform the test, you'll need to manually turn the engine. The best point, to turn the engine with a 1/2 ratchet wrench and a socket, is the crank pulley.
You'll need to lift the vehicle to gain access to the crank pulley. Use jack stands to hold up the vehicle... DO NOT trust the jack. Your safety is your responsibility, so take all necessary safety precautions (which include using safety glasses).
TIP 2: Do not turn the engine with the starter motor, when doing the crank sensor test. Using the starter motor will severely decrease the accuracy of your multimeter test results.
TIP 3: If your GM vehicle starts and runs... the crank sensor is good, and this article will not help you.
TIP 4: Since this is an On Car Test of the crank sensor, DO NOT remove the crank sensor to test it. In the photo you'll notice it's out... but this is just to make it easier to explain the test to you.
The one symptom that's gonna' be staring you right in the face is your GM pick up or van or SUV cranking but not starting.
More specifically, you'll see one or all of the following symptoms when the crank sensor fails:
The thing to remember about having a failed crank sensor, is that if you have spark or fuel injector pulses, the crank sensor is OK and not the cause of your No Start Condition.
The crankshaft position sensor, on your 4.8L, 5.3L, 6.0L GM vehicle, is a Hall-Effect three wire crankshaft position sensor. As such it has 3 wires coming out of its connector.
This also means that this type of crank sensor creates an On/Off DC voltage signal that can be easily measured with a multimeter, an Oscilloscope, and even an LED Light. In this article, I'll show you how to test the crank sensor with a multimeter.
Each one of the three wires that connect to it have a specific job to do. In a nutshell this is what happens when you turn the key and crank the engine:
The most important thing to know, is that if the crank sensor goes BAD, your 4.8L, 5.3L, 6.0L GM vehicle vehicle will ‘Crank but Not Start’.
“A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools.”