any help would be appreciated,i'm new to this forum,here's my problem,none of the interior lights won't come on,the windows,trunk,& it won't start,but all acc come on,have no codes,and the bcm is not wet,i have check all the fuses,just to let you know how it happen,i was vaccuming out my vette and moved the bcm and the interior blink,i moved it again then that's when it all just stop working,i also tried my bcm on another vette that has the same serv # so my bcm works fine,what do you think it could be ?????????

 

my guess would be a ground. there's an extensive sticky thread about electrical issues. these cars are very sensitive! most common problems are bad grounds or bad batteries, the C5 needs a healthy battery and it acts very strange at times when the battery is too old or not charged properly. that would be a good place to start!

 

I have the same exact problem and dont know what to do, if anyone can please help

 

battery is strong,car was fine that day i was washing it,then went to clean the inside,kind of touch the bcm it made a clicking noise like it was a relay,touch the bcm again to make sure the clicking was bcm then all of a suddent stuff stop working

 

Well since the problem started right after you moved your BCM I would start there. Check all of the wires and harnesses going into it and check for tight connections and look for damage...

 

i don't mean to sound like i'm tring to be difficlt,but i spent about 2hrs checking connections and there is no sign of any kind of damage,what else dose anybody think it could be,errrr

 

Start by checking all the BCM fuses. There are several of them BCM 1 BCM 2 etc................ Heres a post that gives you some that I would check.

-C5 ignition Switch repair - http://forums.corvetteforum.com/c5-t...ch-repair.html

 

When the car no-starts, try this.
1) Turn key off and remove from ignition lock.
2) Pull fuse #25 (in the passenger footwell fuse/relay box), wait 5 secs, and re-insert fuse.
3) Try to start the car : IF it now starts OK, you have a BCM problem : it does not send the PCM the "Fuel-Enable" signal.

My symptoms were NO -start, no interior lights, no trunk/hatch release.....

It sounds like the same exact BCM problem I had with my 01 6spd. I did a lot of troubleshooting and this is the "story". And no, my BCM never got wet. I also checked all the BCM grounds and power feed circuits, and my door wires.

When everything works properly : the BCM is the "Power Master" of all the computer boxes hanging on the serial data bus. When you shut the car off, then remove the key, and then open the door, this starts a power-down timer in the BCM. This timer is about 20 or 30 minutes. If the BCM sees no activity (key put in ignition, a door open...) during this 20 minute period, it sends a "Power Sleep" mode signal to all the other modules on the bus, and they go into a low-power sleep mode (so the battery doesnt get drained). The BCM goes into a sleep-mode too, but it still has enough functionality to recognize that a door has been opened, or a key was inserted into the ignition switch, which terminates this power-down timer and wakes-up all the modules. This sleep functionality of the BCM is also there for the anti-theft horn alarm. In sleep-mode, the BCM can also recognize a hatch-release request from the RF remote control (key fob), and then the BCM activates the hatch release relay. (The hatch release signal comes from the remote radio receiver and is transmitted to the BCM on the serial data bus.)

If you have this no-start problem, the issue is that the BCM does not come out of its sleep mode : it does not respond properly to the door-open switch inputs (or the key-in switch input, or the hatch release request). If you try to start your car before this timer runs-out (as evidenced that the interior lights come-on when you open the door), the car will start. If this timer expires, and all the modules (including the BCM) go into sleep-mode, your car won't start. The problem is internal to the BCM : It does not come out of its sleep-mode when you open the door, or stick the key in the ignition (the "key-in/out" switch). If you pull passenger footwell fuse #25 (the one shared by the Instrument cluster and the BCM), and then reinsert it, this forces a power-on-reset of the BCM logic, which forces it to come-up in the waked-up state, and now the car will start. Fuse #25 is the power feed to the BCM logic/CPU circuit. So that I could still drive the car, I rigged-up normally closed pushbutton switch in-series with fuse # 25, so I could reset the BCM before I started my car. And yes, I verified that all the correct power-feeds, grounds, and switch inputs were present at the BCM connectors. I even bought a spare BCM module, and started tracing out its internal schematic, in an attempt to find the defect of the wake-up circuit.

Now for the weird part. After using my pushbutton BCM reset switch for many months, I noticed my BCM began to behave normally. I noticed that the interior lights once again came on when the door was opened. I still have my pushbutton wired into the fuse-box, but have not had to use it anymore.



You have 3 options to fix this :
1) Kludge-fix it with a pushbutton switch
2) Replace the BCM with a new one (get the correct pn, there are 2 or 3 BCM part numbers used, depending on the model-year), but you must get the replacement BCM programmed by a GM dealer for your cars RPO options. Because the car won't run without this programming, you will have to have a GM dealer do the BCM replacement and reprogramming.
3) Find a used BCM, of the correct pn on EBay (or wherever), whcih has the same options as your car does, and therfore already has the correct RPO programming.


My pushbutton kludge fix : Take a mini-fuse, cut apart the plastic and save the metal pins (cut the fuse element that is between the pins. Then solder on a length of insulated wire, from one pin to an automotive blade-type fuse-holder. The other side of the fuseholder pigtail to some more wire, to the Normally Closed (NC) contact of a momentary bushbutton switch. Connect the other terminal of the switch (C) to another length of insulated wire, the other end is soldered to the 2nd fuse pin. Install shrink tubing to insulate all the connections. Install a blade fuse (same Ampere rating as fuse #25) into the added fuse holder, then plug the mini-fuse pins into the fuse-box, where fuse #25 was. To start your car, push and release the bushbutton, then rotate the key and start. Since I don't now need to use the bushbutton, I just coiled the wire up in the pasenger footwell, tucked out of sight in case I need it again.

Note : The antitheft horn alarm will not be functional if your BCM has this wake-up problem, nor can you pop the hatch from the keyfob or the dash switch unless you hit the pushbutton first.

---------------------------------------

Some more BCM info I have written-up in the past :

Some BCM Info :
BCM +12V power feeds
Fuse #25 = BCM Logic Power Feed
Fuse #23 +Power feed for 12V BCM Drive outputs (CL)
Fuse #13 = 12V switched from ignition switch (ON, and START positions)
Fuse #9 = 12V from Ignition switch ON and ACC position)

BCM grounds
A9-C1 connector pin Logic Ground
A2-C3 Power Drive Ground

BCM Functions
Traction control switch (sends switch signal to TCM)
Automatic headlamps
Parklamps
Headlamp doors
DRL
Turn signal control
Fog lamp control
Dash light dimming function (HVAC control, console lamp,PRNDL lamp,
Back-up lamp flash when locking/unlocking
Monitored load control (underhood lamp, glove box lamp, vanity mirror lamps, map light)
Interior courtesy lamps
Antitheft horn alarm and TDR (starter cutoff) control
Vehicle Antitheft PassKey circuit
Rear window defogger
Horn
Colum Lock
Hatch release and ajar warnings for (or convertible top cover release)
Key in ignition warning chime
Driver door key unlock signal (disarms antitheft horn alarm)

Troubleshooting info for the C5 serial-data-bus : (by ersatz928)

Every module which talks on the serial bus has it own piece of wire which comes to a"star" junction. The star junction is where all the wires connect together, so all the modules can talk to each other. There are actually physically two star junctions, located next to each other, to the left of the BCM module. There are two because GM needed more wire connections than one star junction block could handle, there is a short wire that connects the two star blocks together. Each star is a black (or grey?) rectangular plastic block, with lots of wires on one side. It is really just a multipin connector which is plugged-into a shorting socket, which connects all the wires together.

C5 modules (and the databus wire color) on the serial-bus are :
BCM (Light Green)
PCM (Dark Green)
IPC Instrument Cluster (Gray)
DDM Driver Door Lock Module (also controls the window) (Brown)
PDM Passenger Door Lock Module (also controls the window) (Tan)
Radio (but not the CD Changer) (Orange)
Auto-Climate control head-unit/display (Option) (White)
RCDLR (Radio receiver for the Key-Fob transmitter and Tire Pressure sensors) (Pink)
SCM module for Memory Power Seats and telescope colum (Option) (Brown white stripe)
ESC Electronic suspension shock damping control module (Option) (Dark Blue with white stripe)
EBCM Traction Control/AH module (Light Blue)
SDM (Airbag control) module (Dark Blue)
The Star Bus also has a connection at the Data Link Connector (under the drivers side dash) where you connect a OBD2 code scanner to. DLC pin #2 (Purple wire)

There are three kinds of failures that can take down the whole data-bus :
1) One of the wires is shorted to ground, somewhere along its length between the star junction and the module location.
2) One of the modules has an internal bus-driver/receiver failure which forces a continious positive voltage on the bus.
3) One of the modules has an internal bus-driver/receiver failure which forces a continious low voltage (short to ground) on the bus.

This troubleshooting assumes there is only one shorting problem with the data bus wiring, or one module.
1) Disconnect the battery
2) Use an Ohm-meter (DVM, DMM, VOM..) to measure the resistance between DLC pin #2 (Purple wire, upper row, the pin to the left of the rightmost pin), and to chassis ground DLC pin #4 (Black wire, upper row, fourth pin to the left of rightmost pin). I think the measured resistance should be 5K (5000) Ohms or greater. If it measures at least 5000 ohms, you don’t have a short-to-ground on the data bus. If it is less than 5000 ohms got the next step. NOTE : I need to verify the 5000 Ohm go/nogo resistance.
3) Unplug the 2 BCM connectors. If the low resistance goes to 5000 ohms, the problem is internal to the BCM module, replace it. If the low resistance remains, re-install the BCM connectors and goto the next step.
4) Unplug the shorting socket from both Star connectors. Use your ohmeter to probe one wire at a time, to find the low resistance to ground. Identify the offending bus-wire and/or module by using the wire color associated with each module (see the module list above). 5)Find and unplug the module you identified in step 4. If the low resistance goes away, then that module has an internal short. If the resistance stays low, then the short is in the wire itself, somewhere between the Star block and the module location.

Note : The wire colors are from my 2001 factory service manual, I have not verified that they are the correct colors at the star connector blocks , or if they apply to all model year C5s.

 

ersatz928 is the MASTER of all BCM issues! Hes been deeper into this BCM issues than I ever care to be!

Listen to what hes telling ya if you have his symptoms. I know of TWO other people that have had his exact same symptoms.

BC

 

thanks guys for all your help,i'm really glad i came to this forum,you guys have ben soooo helpful,anyway i finally took my car to the shop,he found two ground wires had came lose that plugs into the BCM and that was the cause of it all,now i'm back on the road,once again thanks to everybody for your help !!!!!!!!