Cobalt 2006 NO START after removal of ecm

[Helixal]

My 2006 cobalt LT 2.2L started running rough a couple of weeks ago. So I cleaned the throttle body - didn’t help. At this point I got 2 engine codes - P0106 map sensor and P0300 random misfire. I put in a new MAP sensor (standard parts brand) - didn’t help and I put the original back in.


At this point I took off the ecm - it plugs into the coil bank. I cleaned the terminals and plugged it back in. Now the car would not start. When I turn the key to on I do not hear the fuel pump run. When I try to start the car I hear the starter motor turn the engine but it does not fire up.

I put in a new ecm (standard parts) - didn’t do anything. Put the original ecm back in. Checked the plugs and they look good. Checked the ecm contacts and they look good. The fuses look good.

I’d like to first get back to where the car was running rough. The no start problem was the result of my removing and reinstalling the ecm.

Would appreciate any suggestions.

Al

 

[Helixal]

Connector voltage



As a follow up, I tested the voltages at the input to the ignition control module with the ignition key in the on position. Looking at the connector with the release mechanism at the top, there are 5 positions along the top row and 4 along the bottom. Numbering from left to right 1) to 5) and 1) to 4)


Top row: 1) black wire 0 volts, 4)white wire 4.7 v, 5)red wire 11.3 v.


Bottom row: 1) brown with white stripe wire .08 v, 2) orange wire 4.7v.


When I clipped on a battery pack the voltages rose from 4.7 to 5v and from 11.3 to 12v respectively. The car battery is no doubt run down.

 

[Helixal]

Fully charged the battery from 38% to 100% still no start. I don’t hear the fuel pump but the engine turns over. Probably no spark since I had someone spray starter fluid into the throttle body when I turned the key.

 

[joeE52]

I'm having similar problems. Did you check power at the fuel pump relay? I'm only getting 2v coming from the ECM. I can't figure out/pin point the problem. I'm leaning towards the ECM, but that's an expensive guess.

Sent from my moto e5 cruise using Tapatalk

 

[Dennis Schiller]

I had a bad ground connection to the top of the valve cover, coil connector.
It will not start without it.

I originally checked for + voltage by connecting pin to voltmeter and voltmeter to battery ground, so I though the coil connector was not a problem. Replaced coil module and plug wire/coil assembly. When that did not fix it, I finally checked for the ground and found it missing. Spent too much time chasing my tail.

By the way, I'm selling mine whole or parts, no interest on craigslist :-(

 

[Helixal]

Dennis: was this the 2.2 engine? If so where is this ground connection?


Al

 

[Helixal]

I just checked the voltage between the black and red wires on the connector to the icm. I got 12.1 v. This suggests that the black is connected to battery ground. I don’t see any other ground connections from the icm or the coil module.

Question: could a faulty coil module prevent the fuel pump from kicking on?

 

[Helixal]

Partial progress?


I replaced the ignition coil module with a Delphi brand unit even though it was sold as an ac delco. But then the one I took out was a Delphi (probably original).


So now I can hear the fuel pump rev up and get a strong spray at the schrader valve. Still turns over but doesn’t start.


Just to test things I disconnected the external connector to the ignition control module, I then turned the key to the on position and I could hear the fuel pump rev up. So here the fuel pump was working even though the new coil module and icm were out of the system.


The only thing that I can deduce from this is that the the new coil module reset something somewhere to allow the fuel pump to engage.


Now I only need a spark.


Any insight would be appreciated.


Alq

 

[Dabs]

You're getting a misfire, did you change your plugs after doing the coil? If No, change them. If not, Did you take the rail off that's connected to the plug boots when messing with the coil?If Yes, make sure the rail is seated correctly on all 4 plugs. Said Rail, check it for cracks/broken because this is an active circuit that connects the coil to the plugs. If it's misfiring but you know it's getting fuel all all 4 injectors, you're missing spark. Even with a 0304 my Cobalt limped w/ 3 cylinders, so you're definitively missing spark.