BCM/PCM Issue?.. Need some serious help!
03-28-2007, 03:13 PM
#1
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BCM/PCM Issue?.. Need some serious help! Okay guys, I'm in need of some assistance.
The car in question is a 2006 GTO (6.0 LS2). I just completed a twin turbo install (GenTT). Anyway, here's the scenario. The battery was relocated to the trunk to make way for the passenger side turbo as they are located under the hood. All seemed well at first.. the night I decide to drive it to the tuner shop is when the strangeness occurs.
When I open the door the high beam indicator, DRL indicator, and blinkers all start flashing and the interior buzzer is buzzing and the trunk release acts as if someone is constantly pressing the trunk release button. In the fuse panel, the interior illumination relay is clicking as well as the power window relay - I verified this last night. Also, there is a relay in the BCM that is clicking as I pulled it (the BCM) from under the glove box area and removed the cover to verify.
I used a Summit battery relocation kit to relocate it along with a streetwires junction box for the hot lead. I took the factory hot wires to the alternator and starter, cut them from the battery clamp and put ring terminals on them (soldered and crimped) and connected them along with the fuse box and the 1/0 gauge hot wire from the battery in the back to the junction block.
For the ground I used a short ground cable to the chassis in the back. To ensure a good ground I took my dremel and ground the surface area clean from any surface coatings/paint and screwed it to the chassis. From this exact same point I ran a 1/0 cable to the front and secured it to the front of the block in the factory ground location under the passenger head bolt. On that same bolt I attached the factory cable that was connected to the negative terminal. Connected to this cable is the alternator and starter ground along with a smaller wire that goes to the fuse box.
That about explains the setup....
This car is notorious for ground issues when relocating to the trunk, but I feel I have that covered and have verified everything with a meter.
Here is more odd behavior... When I do finally get the car to start, it will run fine but there is no tach. Also what occasionally will happen is when I turn the key to the off position, the car stays running only when I remove it from the ignition completely does it turn off.
I have also included a video of what happens when the door is opened: Video Link
Any assistance would be helpful. It's at the shop now and I am about to pull my hair out with this.
Thanks,
Jason
The car in question is a 2006 GTO (6.0 LS2). I just completed a twin turbo install (GenTT). Anyway, here's the scenario. The battery was relocated to the trunk to make way for the passenger side turbo as they are located under the hood. All seemed well at first.. the night I decide to drive it to the tuner shop is when the strangeness occurs.
When I open the door the high beam indicator, DRL indicator, and blinkers all start flashing and the interior buzzer is buzzing and the trunk release acts as if someone is constantly pressing the trunk release button. In the fuse panel, the interior illumination relay is clicking as well as the power window relay - I verified this last night. Also, there is a relay in the BCM that is clicking as I pulled it (the BCM) from under the glove box area and removed the cover to verify.
I used a Summit battery relocation kit to relocate it along with a streetwires junction box for the hot lead. I took the factory hot wires to the alternator and starter, cut them from the battery clamp and put ring terminals on them (soldered and crimped) and connected them along with the fuse box and the 1/0 gauge hot wire from the battery in the back to the junction block.
For the ground I used a short ground cable to the chassis in the back. To ensure a good ground I took my dremel and ground the surface area clean from any surface coatings/paint and screwed it to the chassis. From this exact same point I ran a 1/0 cable to the front and secured it to the front of the block in the factory ground location under the passenger head bolt. On that same bolt I attached the factory cable that was connected to the negative terminal. Connected to this cable is the alternator and starter ground along with a smaller wire that goes to the fuse box.
That about explains the setup....
This car is notorious for ground issues when relocating to the trunk, but I feel I have that covered and have verified everything with a meter.
Here is more odd behavior... When I do finally get the car to start, it will run fine but there is no tach. Also what occasionally will happen is when I turn the key to the off position, the car stays running only when I remove it from the ignition completely does it turn off.
I have also included a video of what happens when the door is opened: Video Link
Any assistance would be helpful. It's at the shop now and I am about to pull my hair out with this.
Thanks,
Jason
Last edited by Jason Carraway; 03-28-2007 at 03:31 PM.
03-29-2007, 11:41 AM
#3
That is definitely a ground problem. Did you remove a headbolt and then reinstall it with a battery cable under it or am I reading it wrong? Or are we talking about a bolt threaded into the head from the factory. Make sure your battery to frame, frame to block, frame to body, block to core support grounds are intact and clean. Last but not least is there a chance the battery could be dead even though I am sure it has been checked. I am sure you will find your problem after going through these.
03-29-2007, 02:29 PM
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I was referring to the bolt threaded to the head from the factory, the one that already has the small ground ring on it.
Battery to frame is good, frame to block was definitely good, Frame to body, but not block to core support, I haven't even checked that. I've gone pretty much all over upfront with my meter... 12.54, battery is reading 12.54 as well when not under load and under load it's 12.36. Most fully charged batteries are 12.6 and just to make sure I connected the battery charger/starter in the back and cranked it up to start mode (225A) and still the same.
It's at the tuner shop now and they are saying it's definitely an electrical connection issue too, I just can't see how I missed it. The thing that get's me is that it worked for several days without issue, then the night I got to start it to take it to the shop (of course) is when it happens... go figure.
Battery to frame is good, frame to block was definitely good, Frame to body, but not block to core support, I haven't even checked that. I've gone pretty much all over upfront with my meter... 12.54, battery is reading 12.54 as well when not under load and under load it's 12.36. Most fully charged batteries are 12.6 and just to make sure I connected the battery charger/starter in the back and cranked it up to start mode (225A) and still the same.
It's at the tuner shop now and they are saying it's definitely an electrical connection issue too, I just can't see how I missed it. The thing that get's me is that it worked for several days without issue, then the night I got to start it to take it to the shop (of course) is when it happens... go figure.
03-29-2007, 05:58 PM
#5
Anybody that gets by without running a ground cable all the way back to the engine in an EFI car is just plain lucky. I hope you are measuring voltage drops when checking your connections, not just using an ohm meter. An ohm meter won't tell you much there.
04-09-2007, 07:59 AM
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Okay, problem solved. It definitely was a ground. On the back of the fuse box, there is a wire that runs into a connector. The receiving end of the connected has a L shaped metal bracked that is grounded to the inside of the fender well. That connecter was loose. Once the ground was re-established, it worked fine.
Gotta love the the ground gremlins.
Gotta love the the ground gremlins.
