Although a scan tool is a must-have tool, you don't need one to diagnose the camshaft position (CMP) sensor on the 1996-1997 5.2L/5.9L Dodge Ram 1500/2500 pickup.
With 3 simple tests, that are done with a multimeter, you can find out if the CMP sensor is bad or not and I'll show you how in this tutorial.
I'm also going to show you where you can buy the camshaft position sensor and save a few bucks.
NOTE: The camshaft position sensor is also known as the distributor pickup coil.
Contents of this tutorial:
- Symptoms Of A Bad Camshaft Position (CMP) Sensor.
- Circuit Descriptions Of The Camshaft Position Sensor.
- Where To Buy The Camshaft Position Sensor.
- TEST 1: Testing The Camshaft Position Signal.
- TEST 2: Making Sure The CMP Sensor Has 5 Volts.
- TEST 3: Making Sure The CMP Sensor Has Ground.
- More 5.2L, 5.9L Dodge Ram Diagnostic Tutorials.
APPLIES TO: This tutorial applies to the following vehicles since they use the exact same camshaft position (CMP) sensor:
- 5.2L V8 Dodge Ram 1500 Pickup: 1996, 1997.
- 5.2L V8 Dodge Ram 2500 Pickup: 1996.
- 5.9L V8 Dodge Ram 1500 Pickup: 1996, 1997.
- 5.9L V8 Dodge Ram 2500 Pickup: 1997.
- 5.9L V8 Dodge Ram 3500 Pickup: 1996, 1997.
WIRING DIAGRAM: You can find the ignition system wiring diagram here:
Symptoms Of A Bad Camshaft Position (CMP) Sensor
As you're probably already aware, the engine needs fuel and spark to start. The fuel injection computer uses the signals that the camshaft position (CMP) sensor and the crankshaft position (CKP) sensor create to start activating the fuel injectors and the ignition coil.
So when the camshaft position sensor fails, the engine will not start due to lack of fuel injection and/or spark.
The fuel injection computer monitors the CMP signal as soon as the engine starts to crank. So when this signal is missing, it will usually set a camshaft position sensor diagnostic trouble code.
When the fuel injection computer does set a trouble code, you'll see:
Usually, but not always, when the CMP sensor fails you'll see the following trouble code stored in the computer's memory:
- P0340: No Camshaft Signal At PCM (1996-1997 OBD II system).
Circuit Descriptions Of The Camshaft Position Sensor
The camshaft position sensor needs power and Ground to activate and produce its signal. As such, it has 3 wires coming out of its electrical connector.
In the table below you'll find a short description of each of the 3 wires:
|1996-1997 Camshaft Position Sensor Connector|
|1||Violet with white stripe (VIO/WHT)||5 Volts DC|
|2||Black with light blue stripe (BLK/LT BLU)||Sensor Ground|
|3||Tan with yellow stripe (TAN/YEL)||CMP Signal|
The following ignition system wiring diagram will further help you identify the camshaft position sensor circuits:
When testing the CMP sensor, it's important to know that it creates an ON/OFF voltage signal as the engine turns. ON is when the CMP signal is at 5 Volts DC. OFF is when the CMP signal is at 0 Volts.
The cool thing is that we can see this ON/OFF voltage switching between 5 Volts and 0 Volts with a multimeter, and this is how we're gonna' test it.
Where To Buy The Camshaft Position Sensor
The following links will help you comparison shop for the camshaft position sensor (distributor pick-up coil). I think you'll save a few bucks:
TEST 1: Testing The Camshaft Position Signal
Generally, when the camshaft position sensor fails, it'll usually stay stuck producing a single voltage value as the engine turns.
For our first test we'll connect a multimeter to the CMP signal wire and check to see if the sensor's signal voltage is switching between 5 Volts and 0 Volts.
If the CMP signal does not switch ON and OFF, as the engine is turning, then the next step is to make sure that it's getting Ground (in TEST 2).
The wire that we need to test for the signal, is the tan with yellow stripe (TAN/YEL) wire.
IMPORTANT: The camshaft position sensor must be connected to its engine harness connector for this test to work. You'll need to use a back probe or a wire piercing probe to read the CMP voltage signal within the wire. You can see an example of a wire piercing probe here: Wire Piercing Probe.
NOTE: Don't have a multimeter or need to upgrade yours? Check out my recommendation: Buying A Digital Multimeter For Automotive Diagnostic Testing (at: easyautodiagnostics.com).
These are the test steps:
Place your multimeter in Volts DC mode.
Disconnect the ignition coil from its electrical connector. This is an important safety precaution!
NOTE: Don't remove the distributor cap from the distributor. The distributor cap must be in place to hold down the camshaft position sensor.
With the red multimeter test lead, probe the tan with yellow stripe (TAN/YEL) wire of the cam sensor connector.
NOTE: The camshaft position sensor must remain connected to its engine wiring harness connector to be able to read its signal.
Connect the black multimeter test lead directly on the battery negative (-) terminal.
Have your helper crank the engine for a few seconds once the multimeter test lead connections are set up.
Your multimeter should see the voltage switch between 5 Volts and 0 Volts DC as the engine is cranking.
Let's examine your CMP signal test result:
CASE 1: The ON/OFF voltage signal is present. This is the correct and expected test result.
This test result tells you that the CMP sensor is good and that it IS NOT behind the no-start problem you're diagnosing.
CASE 2: The multimeter DID NOT read the indicated ON/OFF DC voltage. This test result usually means that the camshaft position sensor is defective.
Before you replace it, make sure it's getting power and Ground. For the next test go to: TEST 2: Making Sure The CMP Sensor Has 5 Volts.