TEST 2: Making Sure The Cam Sensor Is Getting Ground
Our second test will be to verify the presence of Ground in the black (BLK) wire of the distributor's 4-wire connector.
This black wire connects to the female terminal labeled with the number 3 in the photo above.
To test of the presence of Ground we're gonna' do a multimeter voltage test on the terminal.
These are the test steps:
- 1
Set your multimeter to Volts DC mode.
- 2
Disconnect the 4-wire connector from the distributor.
- 3
Probe the female terminal labeled with the number 3 with the black multimeter test lead.
NOTE: Be careful not to damage the female terminal of the connector with the black multimeter test lead. - 4
Connect the red multimeter test lead directly on the battery positive (+) terminal.
- 5
Your multimeter should register 10 to 12 Volts DC.
Let's examine your test result:
CASE 1: Your multimeter registered 10 to 12 Volts. This is the correct test result and lets you know that the camshaft position sensor has Ground.
Now that you've made sure that the camshaft position sensor is getting 12 Volts and Ground, the next test is to verify the presence of the 1° POS signal. For this test go to: TEST 3: Verifying The 120° REF Signal.
CASE 2: Your multimeter DID NOT register 10 to 12 Volts. Without Ground the camshaft position sensor will not function.
This is a chassis Ground so it's an easy matter to repair it. Repair the Ground wire and retest.
TEST 3: Testing The 120° REF Signal
Now that you have confirmed that the camshaft position sensor is getting 12 Volts and Ground, we're gonna' test the 120° REF signal with an LED light.
If you don't have an LED light and need to see what it looks like, you can see an example of it here and where you can buy one: The LED Light Test Tool And How To Make One.
The wire that carries the 120° REF signal is the green with yellow stripe (GRN/YEL) wire of the 4-wire connector.
The GRN/YEL wire connects to the female terminal labeled with the number 1 in the photo above.
NOTE 1: Both 4-wire distributor connectors must remain connected to each other for this test to function. You'll need to use a wire piercing probe to connect the LED light to the GRN/BLK signal wire. You can see an example of this tool here: Wire Piercing Probe.
NOTE 2: This test requires that you turn the engine by hand (with the appropriate tools). Don't use the starter motor to test for the 120° REF signal.
IMPORTANT: The fuel pump fuse must be removed before attempting this test. You can find the location of the fuel pump fuse here: Fuel Pump Fuse Location.
OK, these are the test steps:
- 1
Locate the GRN/YEL wire that connects to the female terminal labeled with the number 1 in the photo above.
- 2
Connect the red lead of the LED light to the GRN/YEL wire. You'll need to use a tool to pierce the wire and then connect the LED light to this tool.
IMPORTANT: The distributor must remain connected to its electrical connector. - 3
Connect the black lead of the LED light to the battery negative (-) terminal.
- 4
Turn the key ON but don't crank the engine.
- 5
The LED light should be off. If the LED light is ON at this point, the camshaft position sensor is bad.
- 6
Slowly turn the crankshaft pulley by hand using the appropriate tools when you have everything set up.
Remember, the fuel pump fuse must be removed before attempting this test. - 7
The LED light should flash ON and OFF as you turn the engine by hand.
Let's analyze your test result:
CASE 1: The LED light flashed ON and OFF as you slowly turned the crankshaft pulley. This is the correct test result and confirms that the 120° REF signal is present.
The next step is to test the green with black stripe (GRN/BLK) wire for the presence of the 1° POS signal. For this test go to: TEST 4: Verifying The 1° POS Signal.
CASE 2: The LED light came ON as soon as you turned the key ON and without turning the crankshaft pulley. This test result tells you that the camshaft position sensor is bad. Since the camshaft position sensor is not sold separately, you'll need to replace the distributor.
If you'd like to save some money, check out my distributor recommendations here: Where To Buy The Distributor And Save.
CASE 3: The LED light DID NOT flash ON and OFF as you turned the crankshaft pulley. This test result tells you that the camshaft position sensor is not producing the 120° REF signal.
You can conclude that the camshaft position sensor is bad if you have confirmed that:
- The ignition coil does not spark.
- The BLK/WHT wire is supplying 10 to 12 Volts to the cam sensor.
- The BLK wire is supplying Ground to the cam sensor.
- The camshaft position sensor is not creating a 120° REF signal.
The camshaft position sensor is not sold separately. You'll need to replace the distributor. If you'd like to save a few bucks on the distributor, check out my recommendations here: Where To Buy The Distributor And Save.
