ive got my dash ripped out to install the hud. between work and the weather in fl have not been able to spend the time putting back together. went out to my car this morning and completely dead. hooked up battery charger on lowest setting maintenance free. went inside the car and hear some buzzing. its coming from under the passenger side dash. its the silver box next to the fuse box. i disconnected the battery and charger. worked today and went back out to it tonight. its not wet anywhere, ive pulled the carpet out all around and no sign of water. i hooked it all back up to confirm the source of the buzzing sound. its the silver box with cords everywhere. not sure what exactly it is. ive got to go thru the shop manual to see what it is and possible problems. anyone else have this happen before, or any ideas. thanks in advance.

 

That shiny box is the BCM. The battery is either completely dead, or toast. disconnect the battery cables, and charge the battery stand alone.

 

i had a feeling thats what it was (bcm), but didnt want to make any assumptions. and as noob as it sounds, everyone would know what i was talking about. the battery is a optima red top battery about a year old, and i havent had any problems with it up to now. ill disconnect and charge overnight on the maintenance free, trickle charge. any idea why the buzzing. also with the battery disconnected, im not going to lose my tune am i? thanks for the speedy reply. im pretty concerned with the buzzing.

 

Low voltage will cause various relays to buzz or chatter. You can't lose the tune, unless the internal memory to the PCM is corrupt, or the PCM is damaged.

 

awesome. that makes me feel a little better, i wonder what would drain the battery overnight.

 

Good question. You have a lot torn apart. Considering what you are working on, I would have disconnected the battery before anyways....

 

its been torn apart for over a week now and have not had any problems. just all of a sudden happened. i took battery out last night and trickle charged all night and today. going to put battery back in and see what happens. thanks for your help so far

 

took air compressor and blew out every nook and cranny, hopefully hit any drain areas to make sure they are clear. replaced the battery, and the car started right up. no buzzing noise. checked it a few hours later and no buzzing. we'll see what it does tomorrow. thanks for the input.

 

nope. charged the battery all wed night, and thursday. last night cleaned it all out, and hooked up. no buzzing, car started. shut off. checked a few hours
later and all was good. this morning and low voltage. disconnected battery and back at square one. the only thing that has changed is the heads up display unit is hooked up. ill disconnect the hud unit today at lunch and see if i can get car started. has anyone have this happen to them before?

 

im assuming that someting is wrong with the heads up display unit. something is grounding out. ill check it its hot, but has this happened to anyone else? if i find that the hud unit is the problem, is there anything i can do to fix or rebuild it?

 

You don't have to assume, just audit the currrent draw.

http://forums.corvetteforum.com/1567522286-post590.html

 

great info, thanks again

 

battery completly drained in a less then a day. any tips on finding?

 

last night after dark i checked and no lights on in the interior. so heres where im at. havent had any electrical problems in well over a year. got optima red top battery that holds a charge and solid voltage. took the dash out. had to drive to work in car with no dash. just plugged the cluste back in. last week thurs. i wired in the heads up dislpay. drove to work friday. cluster and hud working. running around all weekend and didnt have time to touch it. monday morning, battery completely dead. put charger on, and got buzzing sound from bcm. removed the battery and trickle charged overnight. checked voltage in mornig and voltage good. after work checked voltage and all good. reinstalled battery and no probelm. no buzzing, car starts right up. left over night, and in morning, low voltage warning, and starter clicking. got home after work and battery complely dead. disconnected the battery and am searching frantically to figure out whats going on. one idea i had was that somehow a few days after dash removal, a wire connected and grounded out the hvac fan. the fan is activated when grounded (for some reason that still alludes me) but i removed the plastic cover over the hvac fan, and nothing. when the battery was full the fan was off. i turned it on and went from lowest to highest setting, then shut off again. so its not the hvac fan grounding out. the new things in installed worked fine for several days with no problem. i have found no water around the bcm, or evidence of moisture. im lost and getting to the point of dropping off at at shop. i ussually can fix my car thru the use of forums, the shop manual, or experience, but im have no clue on this one.

 

The case is hot, so yes, if you ground it..that's what happens. That's why there is a warning in the servcie manual, when replacing the blower motor for this reason.


Bill's procedure is pretty simple(link I posted). Do you not want to follow it, or just don't understand how?

 

i understand the link and i will check out some of the areas pointed out. i know i have a power drain, dont need to test for that. still good info. the next thing im going to do is charge up the battery, hook it all up. wait for the car to go to sleep mode, then check voltage at each fuse. that will at least point me in the right area

 

I'm not following your logic here. If you have 20 circuits, that feed off the battery buss, they will all read the same voltage at the fuse. Reading voltage tells you nothing. Measuring the current draw does.

 

that makes sense. i understand what your talking about now. the write up didnt mention removing each fuse and watch for lower current draw. im not so great with electrical (never had problems beyond changing alternator and battery.) thanks for the input and patience. this should head me in the right direction