Missing ground?

[rjenkinsgb]

With the sensor (and battery) disconnected, what resistance do you get between the two connector terminal on the harness side?
An with it disconnected but battery on, do you still get 2.5V on both terminals?

It is possible the input amplifier uses a "virtual earth" configuration, feeding current back through the sensor to cancel out the voltage whilst still amplifying the signal.

It's also possible that the sensor cable or the ECU input has a short.

 

[Uluz2a6]

I verified that there is also no spark from coils.

ECM works in another Cobalt of same year. The ECM from that vehicle also provides 2.5V on both sides of the circuit

 

[shortbus=]

I verified that there is also no spark from coils.

Check all of the fuses, there may even be a fuse box under the hood. Many GM cars have ignition fuse that the coils get power from.

 

[Uluz2a6]

All fuses are good. Both the injector harness and ignition harness have proper 12V 5V and ground

 

[shortbus=]

Then my next thing if doing this for myself would be to try another coil pack. Since from what I've seen online that is what gives the signal for the injector timing. From reading no spark means no injection, and you don't have spark.

 

[Uluz2a6]

I also swapped coil pack/ignition module with the running Cobalt. No change. It's truly maddening. I am convinced it's a circuit to the ECM that is missing or open. I feel it's a ground that is open. I am still scouring the harness inch by inch

 

[shortbus=]

have you went on one of the Cobalt forums to ask about this? They, dedicated brand forums usually have some guys that have worked as line mechanics in a dealership and are pretty good and are usually helpful.

If you get an answer from one of those forums please update this thread with the cure, to help others.

 

[Uluz2a6]

Update.

I was wrong before. I do NOT have an AC signal from the sensor while cranking. I am certain crankshaft is correct as well as sensor is known good. The only "difference" from original recipe, is engine block has been changed. Data base I am searching shows blocks are similar for multiple years, with some changes. No change to the crankshaft position sensor location or bore that I can find. I may experiment and "shave down" the sensor in attempt to bring it in closer contact to the crankshaft

 

[rjenkinsgb]

If the engine block (and crankshaft) is from a different year, quick search finds info on the sensor being a different type from 2007 onward.

The 2005 uses is a simple two wire coil, the 2007 an "active" sensor with a power feed and internal electronics - and totally different crank wheels the pickups work with; 7 tooth for 2005, 58 tooth for 2007.

See the answer in this article:

https://www.justanswer.com/chevy/a7t8k-put-engine-chevy-cobalt-crank.html