TEST 4: CKP Sensor Resistance Test
As mentioned in TEST 3 (CASE 2), in about 99% of the cases, getting an AC voltage signal (from the CKP sensor) on your multimeter indicates that the ignition module is bad, but not always.
Several readers have reported that in their particular cases, the CKP sensor did indeed produce the indicated A/C voltage in TEST 3 and yet the CKP sensor was bad.
So, in this section, I'm gonna' recommend one more test and it's to measure the crankshaft position sensor's resistance.
Since the CKP sensor is located in a very hard to reach place (on the engine block), you'll test its resistance where the CKP sensor's connector plugs into the ignition module (and not at the CKP sensor itself).
This is what you need to do:
- 1
Put your multimeter in Ohms (Ω) mode.
- 2
Disconnect Connector 2 from the ignition control module.
- 3
Connect the red multimeter test lead to the wire that connects to the terminal labeled with the letter A.
- 4
Connect the black multimeter test lead to the wire that connects to the terminal labeled with the letter C.
- 5
The multimeter's Ohms reading should read 500 to 900 Ohms.
Let's analyze your test results:
CASE 1: Your multimeter showed the indicated Ohms reading. This is the correct test result and it confirms that the CKP sensor is OK.
You can now conclude that the ignition control module is defective (and needs replacement) if you have:
- Confirmed that all six spark plug wires ARE NOT sparking.
- Confirmed it's receiving power (TEST 1).
- Confirmed it's receiving Ground (TEST 2).
- Confirmed the CKP sensor is creating a signal (TEST 3).
- Confirmed, in this test section, the CKP sensor is within the specified resistance.
CASE 2: Your multimeter DID NOT SHOW the indicated Ohms reading. Recheck all of multimeter's connections. Try again.
If the multimeter still does not register the indicated Ohms reading, then you can conclude that the crankshaft position sensor is bad and needs replacement if you have:
- Confirmed that all six spark plug wires ARE NOT sparking.
- Confirmed the ICM is receiving power (TEST 1).
- Confirmed the ICM is receiving Ground (TEST 2).
- Confirmed the CKP sensor IS NOT creating a signal (TEST 3).
- Confirmed, in this test section, the CKP sensor IS NOT within the specified resistance.
Where To Buy The Ignition Module Or CKP Sensor And Save
The following links will help you comparison shop for the Delphi and Standard ignition control module and crankshaft position sensor:
Not sure if the above ignition module and/or CKP sensor fit your particular GM vehicle? Don't worry, once you get to the site they'll make sure it fits. If it doesn't, they find you the right part.
More 3.1L, 3.4L Test Tutorials
If this tutorial was helpful, then the following tutorials will be too:
- How To Test The GM MAF Sensor 3.1L, 3.4L, 4.3L, 5.0L and 5.7L.
- How To Clean The GM Mass Air Flow (MAF) Sensor.
- How To Troubleshoot A No Start (GM 3.1L, 3.4L) (at: troubleshootmyvehicle.com).
- How To Test The Fuel Pump No Start Tests (GM 3.1L, 3.4L) (at: troubleshootmyvehicle.com).
- How To Do A Fuel Injector Resistance Test (GM 3.1L, 3.4L) (at: troubleshootmyvehicle.com).
- How To Troubleshoot Misfire Codes (GM 3.1L, 3.4L) (at: troubleshootmyvehicle.com).
Take a look at following new indexes:
- GM 3.1L Index of Articles (Chevrolet and Pontiac).
- GM 3.4L Index of Articles (Chevrolet and Pontiac).
- GM 3.1L, 3.4L Index of Articles (old section).
- GM 3.1L Index of Articles (Buick and Oldsmobile) (at: troubleshootmyvehicle.com).
- GM 3.4L Index of Articles (Buick and Oldsmobile) (at: troubleshootmyvehicle.com).
- GM 3.1L, 3.4L Index of Articles (old section) (at: troubleshootmyvehicle.com).
Real Life Case Studies From easyautodiagnostics.com Readers
In this section, is input and feedback from all of the folks who have had an ignition control module or crankshaft position sensor issue with their vehicle and found a solution. If you're one of them, thank you for sharing your experience with all of us! If you want to share your repair and/or diagnostic experience, you can use the contact form below.
Real Life Case Study 1
Vehicle: 1996 Chevrolet Lumina Sedan 3.1
Trouble Codes: None
Complaint: NO SPARK “Did the following test, had battery voltage, good Ground and 0.865 ac Volts from crank sensor, replaced module and car still did not start still no spark, pulled off middle coil pack and had battery voltage at spade number 2, tried cranking engine with a noid light on the 2 spades and did not get any lighting pulse”
Extra Notes: “The replacement module is new, even tried a second one because the guy bought it at autozone and i'm not really happy about electrical components from there. I removed the harness and found a small section of the wire worn thru and repaired it. I guess I'll get and led to try the test again. Also put another coil pack on ( used known good one) and had no spark.”
Repair: “ I replaced the crankshaft sensor and car started, the crazy thing is that the new sensor gave me the same readings, around 0.865 ac Volts when cranking and 600 ohms resistance. Thanks for your help. ”
Info Provided Courtesy of: Lou
If this info saved the day, buy me a beer!
