Cranks but will not start and no spark?

It sounds like the crankshaft angle sensor is not working this guide can help us check it with the location of the sensor in the diagrams below.

https://www.2carpros.com/articles/how-to-test-an-ignition-system

If your 2004 GMC Envoy is not starting and there is no spark at the spark plug boots, several potential causes could be contributing to the issue. Here are a few possibilities to consider:

Ignition Coil: The ignition coil is responsible for generating the high voltage necessary to create a spark at the spark plugs. A faulty ignition coil can result in a lack of spark. Consider checking the ignition coil for signs of damage or deterioration. You may also try swapping the ignition coil with another one (if possible) to see if that resolves the issue.

Ignition Control Module (ICM): The ignition control module controls the timing and firing of the ignition system. If the ICM is faulty or not functioning correctly, it can cause a lack of spark. Inspect the ICM for any signs of damage, and if necessary, have it tested or replaced.

Crankshaft Position Sensor (CKP): The crankshaft position sensor provides crucial information to the vehicle's engine control unit (ECU) about the position and speed of the crankshaft. If the CKP sensor is faulty or not sending accurate signals, it can disrupt the spark timing. Consider inspecting the CKP sensor and its wiring for any issues.

Camshaft Position Sensor (CMP): The camshaft position sensor detects the position of the camshaft and aids in determining the correct timing for fuel injection and spark. A malfunctioning CMP sensor can lead to a lack of spark. Check the CMP sensor for any damage or wiring issues.

Ignition Switch: A faulty ignition switch can prevent the ignition system from receiving power or engaging properly. If the switch is failing, it may not activate the necessary components for spark generation. Consider testing the ignition switch or having it inspected and replaced if needed.

Wiring and Connections: Examine the wiring and connections related to the ignition system. Look for loose connections, damaged wires, or corroded terminals that may be causing a disruption in the spark delivery.

Check out the diagrams (Below). Please let us know what you find. We are interested to see what it is.

Hi Joeruss1953,

I am sending you a link to an informative article from this site that features written step by steps intructions and a video on what to check when your cranks but will not start.

https://www.2carpros.com/articles/car-cranks-but-wont-start

I hope this helps you and if you need further assistance please return to the site we are here to help.

Thank you for visiting 2CarPros and have a wonderful rest of your day!

Kindest regards,

Renee
Admin

Scan for codes first then check resistance of cam and crank sensors they may be high not allowing it to start. Check fuel pressure as well auto parts rend the gauges.

Check fuses underhood and scan for codes and check fuel pressure with a gauge should be 60-66psi key on engine off

If you dont' have spark you can put all the starting fluid into engine and it still won't start. You shouldn't use that stuff anyhow. Scan for codes like I said in first reply

If you erased it and it is the same problem the code should come back again. Try another key as I think that still has the diode in key for anti theft. Then check cam and crank sensor connections.

Also check your ignition module autoparts can do that.