I have a 2007 LS 2.2 Liter that will not start. I have had the battery and starter tested and they were fine. I have checked the 50 amp fuse in line with battery and its fine. I hooked up a scanner and I got the code U0100 lost communication with ECM/PCM. I have no idea what to do now. Can anybody help me out? Thanks!

 

check your fuses underhood and in the passanger footwell first. i dont remember if there is a dedicated ecm fuse...but do look!

 

I have checked all of the fuses. There was a fuse for the ecm but it was fine. I replaced it with a spare just incase and still nothing. I'm completely stumped.

 

hey i txt'd you earlier about seein your ad on craigslist. as i said. just hit me up tomorrow and i can try to take a look at it. ill be free all day.

-mike

 

Oh yeah that would be great if you could just give me your opinion on it. I had a friend of mine who worked at anderson toyota for a few years and he isn't 100 percent sure it is the ecm but he doesn't know what else it could possible be. He was thinking a passkey issue? I have no idea about either of them though.

 

can you access any data with a Tech 2 scanner? No communication is usually cause of a poor PCM ground

 

This is where the two grounds are for the pcm and ecm if you want to look at those as a cause.

G103
(CKT 50) Left front of the engine compartment under the left headlamp on the frame rail.

G105
(CKT 451) On the lower left front of the transmission case

 

is it gmlan?? do you communicate with any other module on the high speed data line?? if u have a shorted module on the comm line it will bring down the entire system.... so all the modules on the gmlan would not work

 

Thanks for all of your responses guys. I got a new ecm for it because the old one appeared to be burnt. I opened it up and it had a melted chip and some burn marks. I had it towed to the dealer to have the new one flashed over to my car. I paid 75 bucks for the ecm at a junkyard and the dealer charges 65 to flash it over. I'll let you folks know if that fixes it or not. Thanks again guys!

 

I got it back from the dealer earlier today. It turns out it was the ecm. I just had to get the new one programmed for my car. Thanks everybody.

 

its a loss of communication, usually a modle took a ****. its all a serial data communication, all modules need to work to work

 

Hello just to make sure what to do in my cobalt it don't crank the dashboard has energy when I put it the key on but when I try to starter all the energy gone . The scanner give me the same code u0100 so what you think?

 

I just got this code on my g5. I replaced the ecm and no I can hear the fuel pump and throttle move. But I cant get it flashed to my vin because I still get the same error