Hey, I have an issue with my car that I am trying to figure out.

Occasionally the car will not crank at all. All the electrics come on normally, key over to start and nothing happens. HVAC fan and radio cut out while the key is at the "start" position (normal, right?). This seems to exclusively happen during warm to hot days at the race track and after the car has been sitting after a session for 10-30 minutes. It has never happened when cold, or for that matter, at a place that is not a race track. It seems heat related.

The car has always fixed itself, and eventually will crank again…30 seconds later to 20 minutes later. I have jumped it while it refuses to start, but can't say that it helps. With jumper cables sometimes car starts up again, sometimes it doesn’t help at all. I suspect jumper cables don't fix the problem, they just occupy a few minutes of setting them up. The car is stock. It does seem to have a block heater of sorts that I have never used.

Notes:
- There is a relay that buzzes whenever I key on or key off the car. It seems to be located in the engine compartment, under the master cylinder somewhere. Buried, but it seems louder on the engine side of the firewall than the passenger compartment side. It seems to buzz louder and longer when the car won't start, but that could just be the fact that the engine isn't working. I have no idea what this relay is or does.

- Both the relay buzz and potentially this problem may stem from an issue last year were water got into the fuse box (somehow) when I was washing some overflowed coolant off the car. This caused massive electrical problems until it dried out a day or so later.

- Battery is about 8 months old. This issue has manifested itself for about a year, and when brand new the battery did not resolve this.

- Security light does not complain while this is happening, I believe.

- I have checked all the engine bay fuses, not sure if there is anything else worth checking.

- Gotten a “pull key” error once. Have had a couple “charge system faults” when starting the car from overnight. That’s it for error messages in a year of driving.

Things that have been suggested to me:

- Starter overheating, resistance becoming too high. Dubious to me because it is not *that* temperature sensitive unless engine block heating can overheat the starter. Parking car in shade with hood open and a 5 minute cruise on public roads after a track session does not prevent this.

- Main relay: Common problem on my old car would cause hot no cranks, but I don’t see much literature on it here.

Anyway, any thoughts are appreciated. I don’t like losing sessions at the track and it has cost me a couple.

CodesBattery voltage with engine off, accessories off, key on: 11.9V
Battery voltage with engine off, accessories off, key on, after 5 minutes of writing down all the codes: 12.0V

 

I would bet that is your problem and resolution area. Coolant is not 100% water...and can be slightly aggressive in an electrical situation...you most likely have corrosion in the box. I would remove all the fuses and relays and look at the mating connections, or better yet, just buy a new or used box and swap them out. I'll bet my next pension check it does the trick! On second thought, I need that check!

 

The coolant never got in the box, just water from the hose, for what it is worth.

While drying out things I pulled every item in the box and went at it with a hair dryer. Didn't seem to help, actually, so maybe the water or coolant was causing problems somewhere else. But there were shorts in everything.

 

So you never removed the fuse box, and blew out with compressed air?

 

No, never removed the box or used compressed air. Just hot air from the top, which didn't seem to do much. A day later the car was back to normal, or at least "clock radio turns off with the car off and the motor cranks" normal.

 

Take a look at your connections down at the starter. If you get corrosion or the bolts are not tight it can cause the intermittent problem you are seeing. If it gets worse it will leave you stranded.

 

There are a number of things that could cause this but here are the BIG THINGS that it usually turns out to be………..

First things first!! When it fails to start/crank, HOLD the ignition key over to the START POSITION! (assuming you have an NM6) While HOLDING the ignition switch to START,,,, make and break the clutch switch by slightly pressing and releasing the clutch pedal on and off the clutch switch.

When you make and break that switch,, you SHOULD hear the Theft Deterrent Relay (TDR) in the passengers foot well click ON & OFF. IF,,, you hear that, at least you know that the LOW current side of the TDR CRANK CIRCUIT works.

The OTHER half of the TDR is the HIGH CURRENT side and it supplies 12 VDC (60 AMPS) to the STARTER SOLENOID thru the PURPLE WIRE. If you have 12 VDC on the PURPLE WIRE when the TRD is energized,,, You MOST likely have one of two things wrong.




1. The connections at the starter solenoid are "loose, dirty, corroded, damaged or the solenoid terminals are broken.




OR

2. The Starter Solenoid had an internal issue causing it to fail intermittently! THIS MY FRIEND is a EXTERMELY COMMON and WELL DOCUMENTED C5 & C6 PROBLEM! If it were ME, I would just change out the solenoid if that is determined to be the issue. But that’s ME.

When this issue happens,,,,, If you can RAP the solenoid with a mallet, I bet you a cold one that the starter would magically crank!

So,,,,,,,,,,,,,,,,,,,,,,, My bet is you have a defective starter solenoid.

YES YOU CAN just change the solenoid. If you can find one in the parts store, it about $40-$50 BUT,,,,,, ,,,, you must completely remove the starter to change out the solenoid. I found mine in a starter / alternator repair shop and changed it out which solved the issue 100%

So,, that’s my input.

BC

 

Thanks for the thoughts folks. I will definitely implement that diagnostics procedure next time it craps out, and check the starter stuff.

How bad is the starter to get to? I honestly don't even know where it is. I am fairly mechanically inclined (done the whole Honda engine swap in a driveway sort of thing), but in comparison the Corvette is hilariously complicated. Done all the brakes and fluids (repeatedly) for track work but that is basically it.

Any idea what the buzzing relay I hear is? Could well be not connected to the issue, but still. Based on where the sound is coming from, somewhere midway down the driver's side firewall on the engine side.

 

wtb-z.... FWIW, Bill Curlee and Lucky are the 2 most informative guys on this site! I had the SAME EXACT problem as you last year and they were there the entire way helping me! LISTEN TO THESE GUYS!!!

 

I had very similar symptoms. I changed out the starter, and voila, no more starting problems. http://forums.corvetteforum.com/c5-t...ing-issue.html