I have a 98 SS LS1 with a vortech supercharger and have been running into quite a few strange problems that I hope someone can assist me with. I am having a problem with the cars charging system. When the car is just idling it can usually maintain 14v, but as soon as I begin driving it starts dropping slowly and can get as low as 12v. I have had the alternator tested and verified good. I have removed the positive terminal to see if the car would die, but it maintains voltage. I am seeing a 2.5amp draw with the car off. I have pulled every fuse in an attempt to locate the draw, but it still remains. It seems to be from one of the 3 fusible links by the second fuse block in the engine compartment. I have gone through alldata, but they only describe the location and not what they feed. My battery has been relocated to the trunk, but I have verified all connections to the battery. I have removed the power from the started to see if that was the draw, but it wasn't. I have tried 3 different batteries with the same results. The ASR off light always comes on as well and I can't turn it on. The switch seems to be getting hot.
I am also having a problem with the idle at times running high (1500 rpm +-200). Not sure if this has anything to do with the voltage though. The car has had quite a few modifications done that I don't even know about. I have been unable to find a shop around me that will even look into it. Any help will be greatly appreciated.

Known Mods:
Vortech supercharger with power cooler
Oil pump upgrade
1.7 roller rockers
trickflow pushrods
walbro 255 fuel pump
Loing tube headers
high flow cats
upgraded cam
throttle body
MAF sensor
Probably more I am unaware of.

 

Bump for help. Anyone?

 

got the same problem on my 99 ss shows right at 13v at start up then after warming up drops to around 11v after that getting on it hard will draw power down to 8v.. new alt and even cheaned all the grounds and still draws power i cant figure it out either

 

check/run a continuity test on all of the wiring thats been added to the car... sounds like wiring problem. Make sure everything added to the car that requires 12v, is on a switched circuit, not constant...

 

Thanks for the reply. I will give it a try. Any idea what the 3 fusible links between the fuse blocks feed? I'm really leaning towards them being a big part of my problem.

 

not 100% but I think they are for:
-alternator/battery(if this one is bad u will loose all power to the vehicle)
-starter
-fans? My 96 z28 had fusible link for them anyways...

 

Thank you very much. I will continue my search. Don't think its the battery, alternator or starter, but I could have missed something. Maybe there is a short in the fan. I have heard of people having issues with these fans, but can't remember at the moment what it was.

 

"The ASR off light always comes on as well and I can't turn it on. The switch seems to be getting hot. "

start with that, though its likely not causing yout battery to drain. also, if you have a 2.5a parasitic draw, you need to investigate that.

it sounds as though you've got some a few minor electrical problems compounding . i'd do a voltage drop test on the alternator and battery, find your draw, and replace the ASR switch.

 

I don't think the switch is my draw because it doesn't go away when disconnected. As soon as I can get some time I will perform the voltage drop test and replace that switch. Thank you very much for your assistance.

 

try doing a voltage drop test . on pos and neg bat cables. no more than .2 on pos cable and .3 on neg cable.

 

Is it possible that the ebcm module could be a problem? Is there a good way to check it? I will try to disconnect it and see if my 2.5 amp draw goes away. Maybe if it stops raining I can get a chance to do some more tests.

I was just reading about the voltage drop test and I do agree that this is exactly what I need to do. Thank you to both of you for this suggestion.

 

I used to see this on my SS when I would run the A/C
in summer, but the problem went away once I changed
the fan settings to run low speed full time. Before I did
that I could watch the volts sag slowly as I sat at a
light, and when it got down to 12V it would start to
run rough.

The alternator seems to have some sort of current limit
problem at high temp, low RPM (where it needs the most
field current to make voltage).

I imagine with the blower load, and maybe an intercooler
throwing even more heat into the bay, you're even worse
off.

 

I haven't noticed any change when using the ac. How did you change the fan setting? I assume done through a tuner program?

 

yes you need tuning software to do that. Hp tuners, efi live etc...

 

Have you found anything out on your issue? I have the same problem i was wondering if your fans are the problem.

 

I only had about 30 minutes with it so far due to the weather and kids. I did find a loose, and slightly corroded ground. I have also disconnected the air pump, but was unable to check the amp draw because the meter fuse was blown. Got a new one at work and hopefully tomorrow I can get some more time. Not sure if this is a problem or not, but the air pump line going to the headers was disconnected and just open. Should this be plugged, left open or hooked back to the air pump? Seems like unfiltered air into the exhaust isn't the best thing.

 

I'd cap it off (or remove the spider from the manifolds
and put blockoff plates; I've seen people selling them
but it's an easy fab with a hacksaw and a drill and some
scrap steel, with sheet aluminum (beer can) for a gasket.
Even though you probably won't get much reversion
through a long skinny tube, who needs another tube o'
nuthin' in the engine compartment?

One thing real easy to try, is if you see this when
parked (maybe need idle in drive loading), just open
the hood and see if it gets better in a minute. That
would be the giveaway for the kind of problem I was
having (pullback of the field current limit at high temp).

 

As of the moment I plugged that line. With the long tube headers I assume that it would prefer the added heat, rather then letting it cool too much and mess up the O2 sensors. I will eventually plug them properly. Can get rid of the air pump as well and clean things up. I will check and see if it gets better with the hood open. I have had it both ways, but haven't paid much attention. Thanks for the suggestion.

 

Ok, finally got a day to look into this better. I have narrowed it down to something connected to the BCM. I have the wiring diagram from alldata, but its not gonna be a fun search. Anyone have any suggestions where to start? Was going to look into the security and interior lighting first. Thanks guys

*Edit* Was reading a few things and didn't realize that the BCM will operate for a short time and may account for the draw I'm seeing. Any idea how many amps the BCM draws before shutting down?