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So I have a 2005 Monte Carlo LS with 3400 in it that was running fine before I put new head Gaskets on. After repair, security light isn’t flashing but was steady. I have replaced camshaft, crankshaft, spark plugs, mass air flow sensor, battery, even a new ignition switch and did the relearn process, got the security light to stop flashing and off of message center after I installed it, but now my security light is just steady and won’t go away. Hooked scanner up and got codes u1064, p1626, p1122, p0122. After I hooked a HT200 scanner with GM application that I bought on it, the first codes that popped up on BCM fault was u1300 and u1301. After clearing and trying to crank again, hooked scanner up again and codes for ac started popping up but everything is basically saying circuit or voltage low? Can somebody please possible help me get my baby back on the road. I even bought another engine and still doing the same thing. Say lost communication with bcm for u1300 but my radio, lights, dashboard isn’t lit up like a Christmas tree, windows work, ac and heat works, door locks work, so I don’t know if the bcm is bad because all of that is working. Someone told me that the steady security light is displayed when something is wrong and won’t let it start and disables the fuel. I just need help getting my car on the road I’ve spent so much trying to get this car running.
I'm a little confused, did you replace the head gaskets or the whole engine ? You mentioned that you changed the cam and crankshaft, that's why I'm asking. If you swapped the engine was it the same year or a earlier model ?
I'm a little confused, did you replace the head gaskets or the whole engine ? You mentioned that you changed the cam and crankshaft, that's why I'm asking. If you swapped the engine was it the same year or a earlier model ?
I changed the head gaskets first and the engine was just turning over and not starting so I bought another one and installed it and it’s doing the same thing. The motor I bought came out of a 2004 Chevy Impala same engine. It’s just both engines are turning over but not firing up
Last edited by Charris12; Sep 14, 2023 at 09:27 AM.
At that point id suggest either checking for a 5 volt reference at the sensors (ICM, crankshaft,fuel injection, ect) including the fuseable links and ground's. I'm guessing something has gotten shortened out. Ensure the ground wire from the ECM is connected with the battery cable to the back of the transmission.Also wouldn't hurt check power at the BCM fuse.
Even though it's grounded to the engine id bet the is one. My thoughts are your thinking the right direction. Personally id check the whole harness and see if all wires are connected. Same thing happening twice (no Start) when you did the head gaskets.
Need help asap pleaseee
