suddenly my dash lites started to flicker, along with all the 'display lites' on the a/c control, stereo, and any other little letter or indicator lites.
The front day time marker lites are OUT, The front turn signals do not work but they both flicker fast. When I use the TS lever BOTH of the dash arrows lite up and both flash. The
front flashers BOTH flicker fast, not really flashing,,,,more flickering.
When I turn the parking lites or the head lites ON, the flickering on the dash STOPS, both arrows come on, stay on but the outside from is dark until a TS is used then it flickers again.

When I turn the Key to ON or RUN, all is normal for 5 seconds THEN the dash starts to flicker again. When I start it the same things happen.
The display for the DIC , driver info seems to work, I CAN push the buttons to get gauges, trip miles, etc BUT the lite is flickering so its hard to read sometimes...

Does this sound like the BCM failing??? or the Turn signal lever ??? or a short in the dash display ?

The ONLY thing that has been done lately is I installed sylvania silver star bulbs in the front running lites AND the blinker/marker lite about 2 weeks ago. Nothing else has been touched or changed.

 

By all the symptoms you have described it may very well be a bad ground connection, have you checked your battery cables making sure they are clean and tight. You might check the positive power connections they are located under the engine fuse box cover, one of the cables supplies power to the interior fuse box. Hope this helps.

 

THANKS !
I HAD WONDERED ABOUT GROUNDS... it started suddenly. Not once in a while. I did look up ALL the ground locations and I WILL go thru those today BEFORE selling a kidney to purchase a reman BCM. Best pprice was around $250. Some as high as $750.....

 

I don't believe that the BCM is the cause of your car's problem, I would inspect all the dash wiring, connectors, and grounds before replacing the BCM.

 

In 2014, I paid over $900 for the last brand new C5 BCM the Delco warehouse in Detroit had available. This may not be a bad BCM. If your Multi function switch is original, it is very possible that it is part of the problem. If it is still original, I highly recommend buying a new one now, before GM decides to stop making those, too!! Nothing lasts forever, and if it is still good, it probably won't be much longer! Also check your front turn signal bulbs and sockets. Clean the sockets if required. Also, push your 4 way flasher switch rapidly in and out several times. The turn signals use the 4 way switch to flash them. The 4 way hardly ever gets used, and the contacts become dirty/corroded over time. Also, check your codes, and report back with those. This should get you enough of a start that you'll stay busy!!

 

This may be a bad ignitionswitch problem . It may be a good idea to measure voltage from battery and voltage from ignitionswitch to the system .
If you have a major voltagedrop over the ignitionswitch contacts due to burned contacts internaly it can cause different issues .

 

UPDATE ON BCM QUESTION, FLASHING DASH

I found that when I start the eng, the dash blinks as do any of the illuminated buttons. The frnt markers are OUT and the front Turn sig do not work.
Now, as the dash flashes/blinks if I have the fog lites on they fog lites ALSO flash ! BUT, if I turn the parking lites ON or headlites to ON the dash STOPS flashing, but the 2 TS arrows stay on, and the fog lites stop flashing too. I can leave the fog lites off, and turn on the parking lites or head lites and that stops the dash flashing. Nothing gets me front TS outside. The 2 arrows will both flash, and the rear TSignals work as they should.

Also, i got into the BCM fuse area, No sign of wetness. Nothing there. I pulled many fuses and relays and reseated them with a spot of dielectric grease.

Tomorrow.......Steering column, under-dash & some grounds.

The steering column BECAUSE whoever did the lock-plate removal did a crap job on the plastic covers that do not fit together well now. I am wondering IF there are wires inside the column that were laid out wrong and shorted.
The flashing/ blinking is very rhythmic and not random. There are Clues in the fog lites. Why do they flash ? then stop when headlites come on? Thats why I am thinking TS switch/ headlite switch ?? That thing is almost as expensive as th BCM....

Anyone got a used FSM for the '99 ? with the electrical book? for sale? cheap. I'm old, poor and semi blind. A copy in Braille would work too.

Thanks for the help and advice !

 

Here is a set listed for 150.00
https://www.corvetteforum.com/forums...-manual-s.html

 

I'm inclined to believe you on the ground problem. C5s are known to have several key ground locations that need help. The ones behind each headlight are usually in need of cleaning. Also could be a bad battery cable. Sounds almost like what my C5 does when I first reconnect the battery cables. OP, I'd start by taking apart those multiple grounds at the front, 1 behind each headlight. Clean the prongs, and then apply a SMALL amount of dielectric grease to keep them clean and watertight. Then wiggle your battery cables. You could have a terminal screw that is bottomed into the battery post, and though it seems tight when using the wrench, the cable may still move a little due to insufficient tightening due to the cable bolt being bottomed out before it gets enough clamping force on the cable to battery connection. While you have the battery cables off, put the key in the ignition and turn it back and forth rapidly, like you're turning the car off, then turning it to the start position. Doing this 30 or 40 times will help clean the internal contacts. Then, when your wrist and elbow are ready to fall off, pull the key out, and put it in your pocket. Only then are you safe to reconnect the battery cables. IMPORTANT-I've been told to NEVER leave the key in the ignition switch, or have the key turned to the run position, while connecting the battery cables on a C5. Hope this helps......

 

Well., between snow storms and other such natural disasters i have not made much progress...
I did go thru grounds. No help
I did go thru fuses and cleaned and greased each and the relays and replaced.
I d/c battery charged it to full, reconnected and nothing changed.

I am now going to replace the flasher switch/relay since the flashing IS going thru the relay somehow....making the little button lites flash with the blinkers . Driving/fog lites no longer come on. Last week they DID. Thats what is odd...every few days things change.
Next will changing the ign switch

 

If the problem started after the bulb switch, I would start there. It's possible you installed a single filament bulb in a dual filament socket. That would cause your problem. Just a thought.