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View Full Version : Code U1000 Security Light on No start. HELP!!!


ls698ta
February 13th, 2009, 01:56 PM
So I go outside in the morning to turn on my car and nothing. The security Light goes on. I try to disconnect the batt and remove the ecm fuse. I put it back on and nothing. I hook up the scan tool and there is a code it U1000. So I use the tune tool to disable my vats and upload the tune to the ecm and still nothing. Is there anything I missed out on? Or any other trick out there? Guidance would be really appreciated thanks!!!
chevy052500hd
February 13th, 2009, 02:31 PM
did you do a full reflash? If not try that, are there any body trouble codes, may be a bad ignition switch.
joecar
February 13th, 2009, 02:56 PM
What had you done to the car prior to this morning (when the car was still working)...?

U1000 means something like "Class 2 bus malfunction"

Some module is hogging/abusing the serial bus (i.e. driving it exclusively, either pulling it down or up)...
to pinpoint the offending module, pull fuses for each module until the bus starts working again.

Or the bus is open...

Or one of the modules necessary (PCM to run engine, BCM to validate startup) is broken and not communicating.

What was the donor car that you got your PCM, harness and other stuff from...?
ls698ta
February 13th, 2009, 06:06 PM
Nothing, I did a headers swap last week but it was running fine. I got up this morning to try and start it and nothing the security light is on. Its a 1999 ws6 6 speed with boltons. Original Pcm and harness, car has 59k on it. That's the only code that comes up, u1000. I'll try pulling fuses but wouldn't just disconnecting the battery do the same?
ls698ta
February 13th, 2009, 06:09 PM
did you do a full reflash? If not try that, are there any body trouble codes, may be a bad ignition switch.

wouldn't the vats disabled bypass the ignition switch? Yea I did a full flash I Always do
ls698ta
February 14th, 2009, 04:22 AM
modules are $60 and $10
mr.prick
February 14th, 2009, 05:57 AM
Make sure all your grounds are good.
U codes are a bitch.
joecar
February 14th, 2009, 10:28 AM
modules are $60 and $10
$10 = PCM
$60 = IPC (Instrument Panel Cluster/Controller)

The PCM and IPC usually communicate (VSS, RPM, and a few other things)...

The scantool can still connect with the PCM, right...?

So it seems the PCM can't properly connect with the IPC... or it just discovered that it can't... either broken wire, broken IPC, or missing IPC.