The camshaft position sensor in your Altima's distributor is the one that controls the ignition system and if it goes bad, your Nissan Altima won't start. Although it's called a camshaft position sensor, it's real function is that of a crankshaft position sensor.
As you might already know, the camshaft position sensor is located inside the distributor assembly on your 1997, 1998, 1999, 2000, or 2001 2.4L Nissan Altima, and this article will show you how to test it with a multimeter in Volts DC mode since a simple resistance test of the camshaft position sensor does not exist.
You're also not going to need a scan tool or any other expensive diagnostic tool, just a multimeter and a helper to crank the engine for you.
Contents of this tutorial:
You can find this tutorial in Spanish here: Cómo Probar El Sensor De La Posición Del Árbol De Levas (1997-2001 2.4L Nissan Altima) (at: autotecnico-online.com).
Important Tips And Suggestions
TIP 1: The only way to effectively and accurately test the camshaft position sensor, is by manually rotating the engine. You should not crank the engine with the starter motor to perform this camshaft position sensor test.
TIP 2: You must disable the fuel system by disconnecting all four fuel injectors before starting the test.
TIP 3: It's important that you test for spark first, before attempting the camshaft position sensor test. If you have spark coming from any one of the 4 spark plug wires, then you can accurately assume the camshaft position sensor is OK.
Here's the link to the ignition coil test: 2.4L Nissan Ignition Coil Test (97-01), which you should do first before testing the camshaft position sensor.
TIP 4: The camshaft position sensor is part of the power transistor assembly and is inside the distributor. If the camshaft position sensor proves to be fried, you'll have to replace the entire distributor, since it's not sold separately.
How Does The Camshaft Position Sensor Work?
What's gonna' help you to see the ‘why and how’ of the testing in this article is to understand how the power transistor works. In a nutshell, this is what happens:
The camshaft position sensor is located inside the distributor and is part of the power transistor assembly.
The camshaft position sensor assembly is really a crank sensor, since the fuel injection computer uses it to control the creation of spark thru' the power transistor and ignition coil.
Now, when you turn the key and crank the engine (to start it), the camshaft position sensor/power transistor get power thru' the wire labeled with the number 5 (see photo above of the connector).
As the engine turns, the camshaft position sensor assembly starts to create two specific position signals that it sends directly to the computer. One signal is called the 1° POS Signal and the other is called the 180° REF Signal
When the computer gets these two camshaft position signals, it does its little song and dance and shoots a Triggering Signal to the power transistor.
This Triggering Signal can be checked with an LED Light (which you can do in the article: How To Test The Power Transistor: 2.4L Nissan Altima 1997-2001).
When the power transistor gets the Triggering signal from the fuel injection computer, it now starts to switch the ignition coil's power On and Off. This ON/OFF action is what makes the ignition coil spark and is referred to as the Switching Signal.
If any one of the two camshaft position sensor signals is missing, your Nissan Altima will crank but not start due to a lack of spark.
CAM SENSOR TEST 1: Making Sure The Camshaft Position Sensor Is Getting Power
The first order of business is to check and verify that the camshaft position sensor is getting juice, in the form of 12 Volts.
The wire that delivers these 12 Volts to the distributor is the wire labeled with the number 5 in the photo above.
Alright, these are the test steps:
Set your multimeter's dial to Volts DC.
Disconnect the distributor from its electrical connector.
With the red multimeter test lead, probe the wire labeled with the number 5, see photo above.
Connect the black multimeter test lead directly on the battery negative (-) terminal.
Then, turn the key on (but don't crank the engine).
Your multimeter should register 10 to 12 Volts DC.
Let's examine your test result:
CASE 1: The multimeter registered 10 to 12 Volts. This is the correct test result and confirms that the camshaft position sensor is getting power.
The next step is to check that the camshaft position sensor is creating its two position signals. Go to: CAM SENSOR TEST 2: Checking The 1° POS Signal.
CASE 2: The multimeter DID NOT register 10 to 12 Volts. This tells you that the cause of your Nissan Altima's no start is due to this missing voltage, since without this voltage, the distributor is not gonna' work.
Although it's beyond the scope of this article to troubleshoot this missing voltage, finding the cause of these missing 12 Volts will solve you no-spark no-start condition on your 2.4L Nissan Altima.