Hello all I just picked up a 2003 z06 with some major electrical issues. The car runs and drives fine but ive got various electrical problems throughout the car. The CEL is also on. With the headlight switch in the off position the dash/speedo flickers on and off and I can hear a relay click consistantly in fuse box next to the bcm. When I switch it into the on position every thing illuminates and the relay stops clicking. When the car is turned off various interior lights will stay stay illuminated unless i disconnect the battery. Various functions of the message center will work intermittently like fuel economy, and oil pressure. Front turn signals wont work. The previous owner purchased the car like this and would connect and disconnect the battery and time he wanted to drive it due to lights not turning off and draining the battery. First thing i checked was the bcm/wiring. Didnt find any wire damage, loose connectors, or signs of moisture. One red flag i noticed was the positive terminal has what looks to be an improper bolt jamming the positive lead to it. It seems tight i cant move it around snd car starts strong everytime. Before I take it to the stealership to have it diagnosed, any other common issues i can check out? Here is the slew of codes that are current.

B0502 RH DL relay circuit
B0507 LH DL relay circuit
B2482 back up lamp relay circuit
B2527 horn relay circuit
B2578 right front turn signal monitor circuit
B2583 left front turn signal monitor circuit
B2593 column lock drive B
B0361 left actuator feedback short to ground
B2282 battery #1 circuit
B2284 battery #2 circuit
B2264 mirror position signal
U1064 loss of communication with bcm
B2283 battery #1 circuit
B2284 battery #2 circuit
B2263 mirror position signal fault
B2265 mirror position signal fault
U1255 class 2 communication malfunction

 

I would start with working through the list of ground connections that are known to corrode, loose proper connection. There are a couple threads on the forum that have diagrams of all of them and where they are located. I don't have said diagram readily available so I can't be of much more help. But that is certainly where I would start!

 

With the things you have already checked I might take a peek at the ignition switch to see what it looks like. Could it be possible that the run contacts aren't completely opening when you turn the key to off?

Also, will any of those codes clear and stay away while the battery remains connected?

 

An easy check for the turn signals is to pull the bulbs and check the sockets. The sockets tend to get overheated and burn up. Do the DRL's work or are they out too?

 

The same codes always come back with the battery connected or disconnected over night.

 

Sounds like a ground issue or an old battery - these cars are VERY sensitive to both ground corrosion and battery life. Definitely hit every ground and clean it up, and maybe think about a new battery. There are some great diagrams for C5 ground locations on this forum.

 

You don't state your milage but my 2002 had 87000 when I bought it. It seemed that every other time I drove it a code would present itself. After having the EBCM repaired and updated by ABSfixer, buying a GOOD battery plus keeping it on a Ctek battery tender when not being driven and then replacing the ignition switch and finally the front turn signal assemblies and switching over to LED I haven't had a single code for over a year now and she's running great.

 

OP. Do as some others have told you. All of your B codes are related to voltage levels. Start with the easy ones. Check battery cable connections for clean and positive connections. Then check the battery ground cable ground connection to see if it is clean and solid. The ignition switch is suspect but it is a little more involved than checking the ground and voltage connections that right in front of you just by opening the hood.

Bill