grantv

History; when I bought my Z it had one key and one aftermarket FOB only. The alarm had issues (went off if parking brake applied), so I got 2 new keys and FOB's shortly thereafter. Since then; no blue LED light up, factory alarm works great, all good.
I park it Friday and as I'm going out of town, do not hook up my battery tender. I also, after over 2 years of it sitting on a shelf in my garage, throw away that old FOB. See where this is going?
Well this morning I unlock to go to work; alarm goes crazy, blue LED even. No matter what I do car will set off alarm. End up taking my wife's van.
So... disconnect battery and see if it resets? If so for how long? Check battery voltage (should read?)? Other thoughts or suggestions?

grantv

A bump with some info... got home from work, unlock car, open door and alarm goes crazy. No surprise as I didn't change anything.
Unhook the negative battery cable, and measured battery; 12.1V. This is obviously not right. I'm assuming that my car has a parasitic draw as it only sat for 6 nights. Hooked up a charger, can't recall how long it takes to charge up, have a feeling that I won't be driving it tomorrow morning to work though.
So, anybody have any thoughts?

SilverC54me

If there is an aftermarket alarm system installed uninstall it. Some of these are poorly made. Some installers do not know how to properly tap these into Newer cars (ones with remote unlock/lock like the C5 or newer).

This is also probably the source of your parasitic drain.

Gary

grantv

How and why would this come up after just about 3 years though you figure? Good point that this might be part or most of the battery drain... odd that the PO would have put in a cheap alarm considering his history with the car, but maybe a PPO did.

SilverC54me

Electronic devices do fail. Could be that this was the alarms time.

Gary

grantv

Seems you may be on to something. Charged battery over night, reads 12.8V this morning, drop negative cable back in place... blue lights.
Didn't even try to open the door and wake up my household again. Now to find someone in this town to fix it, hope the alarm let's me drive the car!

Bill Curlee

Your AFTERMARKET system was set up to work with your aftermarket FOB. The person that you purchased it from set it up and made the system work and it was HAPPY (security wise) up until now!
It was HAPPY,,, UNTIL,, the battery went LOW or DEAD or Disconnected. Then it went into a preprogramed look for the aftermarket FOB mode. Since you don't have that fob, its going to alarm ANY time the system senses an additional current draw OR door, trunk or hood or hatch sensor ajar. Until you get a new working aftermarket FOM and reprogram the system to recognize that FOB, your DONE!

If it were me, I would find the alarm ECU and just disconnect it and reconnect the two starter interrupt wires. Your C5 came from the factory with its OWN alarm system that works fine. Why add more???

BATTERY DRAIN. Its possible that the aftermarket system adds some additional current drain in the system. It shouldn't be very much if any.
Its also possible that something inside the car is staying ON when it should be OFF and causing an additional current draw. You should be reading 20-25 milliamps for the normal sleep /security draw. Get an AMP Meter (capable of reading 10amps) and test your actual current drain when the BCM is in sleep /security mode.

On another note! Your battery is rated for a specific RESERVE CAPACITY and the C5 system is designed around that reserve capacity rating. If everything works as designed, your car (NO BS) should be able to sit at a minimum 30+ days and still crank the engine and run without ANY issues WITHOUT having to be connected to a battery tender/charger! PERIOD!

.
Have the battery fully tested and see if it has adequate reserve capacity and the correct CCA.

Bill

grantv

Agree Bill, I never understood why he bothered with an aftermarket alarm. He also installed a crazy $1900 radar system though, so maybe paranoid to protect it (or maybe the radar guy said it was "better").

I bought a new AC Delco when I got the car, but it's only 95RC. Every so often when it gets low (I rarely let that happen, sits on a tender every time I take more than a standard 2 day weekend) I get the pull key message also. So, yes, I need to chase down what is drawing juice ASAP, and also get a new (AGM, higher reserve) battery.

Long story as short as possible… When I bought the car I knew of the alarm issue (strong point from PO; parking brake sets off alarm). I spoke to a guy at the Visions install center at the time, he said he knew the car/PO, and could fix it. I did so myself in a way, so good enough.
Flash to today. Figured I’d take a chance on the same place just in case the guy is still there. Guy comes out, looks familiar, tell him my issue, then tell him the car and PO; Captain JC; “Oh, the Corvette, yeah I installed that alarm. Turn the key to on 5 times; that’ll disable the alarm. It’s a Compu-Star”. Dang, and here I am at work, car parked outside, no blue lights. I’ll probably still take it there to get properly disabled so this doesn’t happen again, but I’m running.