How To Test a Chevy Blazer Cam Sensor

How To Test a Chevy Blazer Cam Sensor


Problems with your Chevy Blazer Cam Sensor can lead your truck not running right. Poor idle or misfire can also occur because this hall effect style sensor is not transmitting the right signals to your Powertrain Control Module. Today I will be showing you how to test your Chevy Blazer Cam Sensor in a 2003 Blazer with a 4.3 liter V6.

Before we get into the testing procedure, it helps to understand just what the cam angle sensor does for your truck. Also known as a camshaft position sensor, this unit relays the specific engine or camshaft position as well as engine speed to the Blazer computer. Your computer or PCM then can accurately time and ignite the fuel mixture in your engine on time.

how to test chevy blazer cam sensor

Common Symptoms of a bad Blazer Cam Sensor

When this Chevy Blazer Cam Sensor starts to go out, you can see a variety of symptoms of problems. Let’s take a look at some of the most common issues.

  • Engine misfire
  • Engine is slow to start
  • Smoke coming from Blazer tailpipe
  • Poor Fuel Economy

Your Chevy Blazer Cam Sensor also sends this signal to your Ignition Control Module or ICM. When you suspect your truck is running rough because of your cam angle sensor or CAS, use this handy guide to troubleshoot your issues.

Check Blazer Cam Sensor for Power

To conduct this How To DIY article, you will need to use an automotive voltmeter or multimeter. Using this tool you will be measuring the sensor for specific ranges to determine whether or not the Blazer Cam Sensor is any good.

The Blazer Cam Sensor in your truck is located near the ignition distributor, and usually mounted to the side of your cylinder head. Because this unit is meant to read the high and low points of your camshaft, it’s easily replaceable by removing just one screw.

First we will be checking your Blazer Cam Sensor for a power signal, which is PIN 3 in the diagram shown below. Turn your Blazer ignition to the “ON” position but don’t start your truck.

how to test chevy blazer cam sensor 3

Measure this pin by putting the black lead of the multimeter to the negative terminal of your battery. You can use a wire piercing tool to get into wire 3, or simply unplug the harness and gently touch the front of the wire. Never force your probe into any wiring harness, as this can cause permanent damage.

PIN 3 should return 12 DC volts with the key turned to the ON position. The next wire you will be checking for is PIN 1 for a ground signal. Once you have determined that you have power and ground at this sensor, it’s time to move onto the last leg of our How To guide.

Check Blazer Cam Sensor for Signal

The last part of our How To guide is of course checking the sensor signal wire. You will require a wire piercing tool or if your multimeter comes with sharp enough leads you might be able to get away with it.

how to test chevy blazer cam sensor 1

This part of the test will require you to measure the voltage at PIN 2 or the middle wire. To do this it’s best to manually turn your engine over, while having your key still at the “ON” position. You can do this using a crank sprocket tool, or a heavy duty wrench to manually crank over your engine.

It may be easier to remove your spark plugs as well, so you don’t have to fight the compression in your 4.3 liter V6. Have a friend turn the engine manually, remember to keep your ignition turned to the “ON” position.

You should see this wire transmitting a voltage that fluctuates from 0 DC volts to 12, as the hall effect sensor reads the high and low parts of your camshaft.

Need to buy a replacement camshaft angle sensor for your Blazer? Check out our online store for a complete collection of our OEMSPEC products and cam angle sensors.