Question: C5 cranks but no start

[jetrocker]

Bought this car in January, but not driven it much yet. When I have driven it, I've always used the same key (I have 2). Yesterday my son came over while I was at work and had to move the vette out of the garage to work on his. He used the 2nd key that was at home. Well, the car cranked fine but wouldn't fire...not even a trace or putt of ignition. He pushed it out in the driveway and left it for me to try with my key when I got home. When I tried, I had the same problem. I cranked it a few times for about 10 seconds each and no joy. After this, the battery was low and finally just stopped turning over the engine, even though interior lights etc still were on. I took the battery out last night and have it on a charger. Last time the car was run about 10 days ago, it started and ran fine.

My question of course is what might I look for to solve this problem, or some logical troubleshooting sequence. Also, would the use of the second key, which I have no concrete knowledge ever worked or is truly matched to the car (dealer purchase), somehow have done something to the VAT or starting system? If the VAT is locking out the start of car, will it still allow the engine to crank?

After having the battery out for 24 hours and now fully recharged, I'm curious to see if anything changes when I try it tonight...but thought I'd ask here today and see if anyone has other input, thoughts, or advice. I'm sure flat bedding the car to the local Chev dealer would be a wallet drainer.... hope I can work this one at home.

Thanks in advance.

Mark in Cincinnati

 

[dadaroo]

A C5 can crank with low voltage but the electronics will not function correctly with low voltage. Charge the battery up and actually measure it's voltage AT the battery and see what happens. A good battery can last 3 weeks with the sleeping mode of the car drawing about 17-22 milliamps. You could have a parasitic drain above that or a battery that is getting old. Let us know what happens.

If later you want to test for a parasitic drain I can provide how to do it and diagnostics to determine what is the cause.



A fully charged battery should be 12.6v ormore. Brand new batteries are not always fullycharged off the shelf.

It's not 12 volts it's 12.6 because each cell is 2.1 volts.

If the battery is

12.5 = 85% charged
12.4 = 65%
12.3 = 50%
12.2 = 35%
12.1 = drained

 

[LLC5]

Have the battery fully load tested with a carbon pile tester. Fully charged does NOT mean that the battery is good, only that it is ready for proper testing. Even if you decide to buy a new battery, have it fully load tested before purchasing, as I have seen many new batteries that are bad. Battery cables need to be clean and tight (not able to be twisted after tightening). Do not skip this part of any diagnosis. Good luck with it.

 

[jetrocker]

Dadaroo - looks like you were exactly right. I fully charged the battery and the car fires up perfectly. LLC5, I will get the battery load tested. It is only 9 months old, but to your point you never know. Thanks very much guys!

PS Now I'm wondering if the aftermarket amp and sub installation in this car is somehow draining the battery faster than it normally would when the car is parked. It was in the garage for a little over a week and this happened. I'm very tempted to just "de install" the custom stuff (was in the car when I bought it) and just go back to a factory stereo setup.

 

[dadaroo]

That's great, thanks for letting us know. The OEM radio has 2 power sources that are always powered and the BCM controls it so it will shut it off when you exit or you can allow it to play for up to 20-30 minutes.

Your aftermarket may be using those sources so if you don't turn it off it may still remain on. You should be able to test and see if it stays on.

 

[LLC5]

Dadaroo - looks like you were exactly right. I fully charged the battery and the car fires up perfectly. LLC5, I will get the battery load tested. It is only 9 months old, but to your point you never know. Thanks very much guys!

PS Now I'm wondering if the aftermarket amp and sub installation in this car is somehow draining the battery faster than it normally would when the car is parked. It was in the garage for a little over a week and this happened. I'm very tempted to just "de install" the custom stuff (was in the car when I bought it) and just go back to a factory stereo setup.

Your aftermarket stereo could be causing a parasitic drain that is too high, but also keep in mind that C5 needs to have a battery with a 120 RC (reserve capacity, which is extremely important) and a 500 CCA rating. Your battery could also be weak or bad from sitting with out use (sulfation, which is why the load test is critical). Glad you found your issue.