Will a bad ECM cause the obd2 not to work?

Good morning,

If the check engine light comes on with the key on and the fuel pump runs for 2 seconds, then the ECM is working and may not be the issue.

Does the engine run? If it does and cannot communicate, it may be the scan tool you are using. Try it on another car to see if it works.

As far as testing, special equipment is required for the actual testing to see if it is good. You could remove it and send it out and have it checked.

What is the exact issue with the car?

Roy

The car cranks and there is spark and fuel, but it will not run.

Okay, the first thing I would do is check the compression to be sure the timing is correct. You should have 140-160 pounds in each cylinder.

https://www.2carpros.com/articles/how-to-test-engine-compression

If you have spark and fuel, the ECM is working.

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

Roy

I will check the compression. The scan tool works fine on my truck.

Okay, keep me updated with the results.

Roy

There appears to be 0 PSI on all four cylinders. I tested the pressure gage with air pressure it is working. The timing belt is intact, and the cylinders are moving when cranking. It seems impossible not to have some pressure even if the head gasket maybe blown. what are your thoughts. 6 weeks ago, I changed the belts, and it was running like a top and then it just stopped running and would crank but not fire.

This sounds like the timing belt has failed and moved from its settings.

You need to remove the front cover and inspect it.

I attached the procedure for removing the belt and inspecting the timing marks. You most likely will find the belt teeth are missing.

https://www.2carpros.com/articles/how-a-timing-belt-works

Roy

I finally had time to look at the timing belt. According to my manual it says that 06 and earlier to line the two white lines on the top sprocket up with the top of the head, when it is the bottom sprocket appears to be 6 teeth off. I do not see missing teeth on the belt but is not broken. Is this far enough off to have caused damage to pistons or valves by rotating engine with the starter. What are your thoughts? Keith

Yes, the belt is off. Follow the instructions for replacing the belt and getting the correct marks lined up.

Roy

are the valves and piston un- damaged with the belt off like this?

You will need to set the belt correctly and then do a compression test.

https://www.2carpros.com/articles/how-to-test-engine-compression

You need 140-160 pounds.

Roy