I just bought a 2002 Firebird 3.8 l couple weeks back and it has some electrical issue where all the lights turn on and off when I do anything. Turning the key, opening doors/hatch, pressing radio buttons, door switches, anything at all really, lights turn on and off for about 2 minutes or so. It's the interior and exterior lights that flash. Car starts no issues and stays running so I don't believe it's the security system. I've checked the fuses I belive could have something to do with the issue, but no luck. I'm kinda stumped on what it could be. I'm not sure if youtube links are allowed but if they are I'll send a video of the issue.

 

You may have a problem with the BCM board:
https://ls1tech.com/forums/wiring-st...der-issue.html
https://ls1tech.com/forums/wiring-st...38138-bcm.html

You can search this site and YouTube for volumes of other information.

 

Yup that's BCM programming or it going haywire.

 

I think your problem lies in the BCM board

 

thanks fellers I'll look into that

 

UPDATE
So, I got behind the glove box to the BCM and found some kind of aftermarket theft alarm thing that was not plugged in but was spliced into the BCM's main plug in wires. I cut the aftermarket thing off (after disconnecting the battery) and spliced the original connector wires back together. plugged it all back in and it's having the same issues, except now it won't start. it won't crank or nothing, turns on with the key but dead when I try to start it. I did a quick visual inspection of the BCM board while I had it out and all seemed good. now I'm really boned here fellers

 

Sounds like the VATS Module is messed up.

 

There is no VATS module in 98-02 f-bodies... VATS is part of the BCM in those models.

Generally, if VATS is preventing starting, the SECURITY light in the instrument cluster will be on. If it's on solid, the system detects a resistance in the ignition key circuit but not the resistance that matches what it expects from the original key. If the light is flashing then it is seeing an open circuit (infinite resistance) indicating there is no key in the ignition (i.e. as though a thief had removed the ignition cylinder). That usually means that one or both of the sensor wires are broken (or have been cut). It's quite possible that those wires were involved in the aftermarket device you removed... especially if it had remote start capabilities.

VATS controls the ground for the starter relay preventing the starter from operating if it detects a problem with the key resistance. Check that the yellow/black wire in the large blue connector at the BCM is intact and secure - that's the starter relay connection. Alternatively, you can simply ground the yellow/black wire at the starter relay to make it work without regard to VATS or the BCM. However, if VATS really is the problem then the car still won't start - it will turn over but VATS will have disabled the fuel enable signal to the PCM. The PCM can be programmed to ignore the missing fuel enable signal, but it would be easier to just do a VATS bypass.

Of course it's always possible that this is a "no start" condition that is unrelated to VATS - they happen all the time.

 

Thanks for the info boss. The security light is not on, but that could be the previous owner taking the bulb out for all i know. That aftermarket thing I cut off turned out to be a vats bypass module from ebay or something. I ended up reading a ton of old forum posts and figured out to ground that black and yellow wire and also decided to try hooking that vats bypass thing back up and it started and ran no problemo. I came back the next day and same issue, no crank. I'm gonna look at my wiring to see if I got a bad connection. Is the right way to bypass vats the 2 wire plug under the steering column or should this bypass module at the BCM have the same effect?

 

This is the bypass module thats wired into the BCM

 

VATS isn't just a wire to the Starter Relay, it kills the Fuel Injectors as well as mentioned above. Check your connections and try bypassing it at the BCM since that's the brain of it.
If your car is tuned and your tuner is local they can turn VATS off in the PCM.


Yes it is, I guess I should have elaborated that part. The VATS component in the BCM is messed up, same setup as the GMT 800 trucks as well.

 

well fellers I dug back into it and turns out the ground wires I had connected were just lose and came undone lol. fixed that and she started right up and kept running so the vats bs is fixed. I'll send a picture probably Monday to show what exactly I did with the wiring (it's not really pretty). it's still doing the light thing but I think I may just need to replace the BCM? dunno but whatever the issue, I'm just gonna have to run it for now.

 

I've tuned vehicles where the VATS component goes bad, turned it off in the PCM and the light is intermittent on the gauges. BCM controls some of those lights.

 

Bypassing VATS can be done under the steering column or at the BCM - it's just opposite ends of the same wires. Most descriptions of how to bypass with resistors use the steering column location only because it's easier to access. Also, the bypass modules sold online are significant overkill for 4th generation f-bodies. They include wires to replace the missing fuel enable signal which are needed on some other GM models but are completely unnecessary on f-bodies - only replacing the ignition key resistance is necessary to completely disable VATS. There are some modules which are designed strictly for convenience by containing all 15 possible resistance values and allowing selection by either DIP switches or a rotary dial switch. These are very helpful when you don't have the original key to measure the correct resistance because they allow you to try each value until you find the one that works.

Yes, VATS disables starting in two ways - preventing the starter relay from tripping by eliminating the ground to the relay coil and disabling the fuel enable signal to the PCM so that the engine will starve for fuel even if it can be cranked. The PCM can be programmed to ignore the missing fuel enable signal (this is what many tuners call disabling VATS) but the BCM can't be programmed, so the starter relay coil ground (yellow/black wire) must be physically rewired to a chassis ground. PCM programming and rewiring the relay will get the car starting but will leave the dash light on or blinking. Doing a bypass eliminates the need for PCM programming and rewiring the relay and also turns off the dash light. It replaces the resistance normally read from the ignition key pellet with the same resistance in the form of individual resistors or, in your case, a module with the resistance built in. If the VATS bypass is successful, there is absolutely no reason to suspect a BCM malfunction or to replace it "just in case". With the exception of the cold solder problem which causes the windows and stereo to cut out, BCMs seldom fail... in the 20+ years I've worked with these cars, I've only seen a very small handful of failures and they're usually obvious physical damage like burned or melted wires from improperly installed alarm systems or VATS bypass modules.

 

Thanks for the info boss, I've gotten the car to start and for it to keep running and there is no security light. But, the original issue of all the lights, interior and exterior, clicking on and off remains. what in the BCM could cause that exactly? When I had the BCM out of the car, I took it apart and all seemed good, and all the wires were intact from what I could trace. By the way, today was quite busy and I didn't get the chance to snap a picture of the wiring to the BCM, tomorrow should be more free so I'll send a picture tomorrow if I'm able.

 

Interior and exterior lights are completely separate circuits so there is no single issue that could cause them all to flash. However, there are circuits in the BCM which control each of those circuits. The interior courtesy lights are managed by a BCM circuit which provides the "theater" dimming effect by gradually reducing the ground available to those lights. The exterior parking lights are controlled by the BCM power lock and optional alarm system to flash as indication that the doors are locked/unlocked or that the alarm has been triggered.

It is remotely possible that the BCM is faulty and causing both of those circuits to misbehave, but I suspect that there's more to the aftermarket module than you think. Could there be an aftermarket alarm system installed along with the VATS bypass module? It would be quite expected to have an aftermarket alarm with remote start capability require the addition of the VATS bypass module to support the remote start capability and such an alarm would often be connected to the lights.

 

As far as I know that bypass module is the only aftermarket thing in the interior, I've looked under the steering column and obviously behind the glove box. The only thing that was suspect under the steering column was the VATS wires being cut off. Everything else seemed to check out to me.