My 2015 coupe's battery went dead. Replaced it with best battery I could find. When I tried to start the car, the control panel went to black and the engine did not turn over. I'm aware of the low battery no start problems, so I bought another new 760 amp. Same problem. The panel lights up as it should, the windows and lights all seem to work The fob is working as well as the doors ,radio and most of the other accessories. When I push the start button everything goes black. Battery voltage is 12.4. I have the shop GM manuals and noted all of the shop tools needed to check systems. Hilo Hawaii does not have a Corvette dealer and will not help. My other option is to some how get it to Honolulu. Okay, The car will not start, Corvettes need to be flat bedded. So I will have truck it to the Port, some how get on the barge, then have the Honolulu dealer get it off the ship and in to there repair shop. I can only imagine what this will cost. That's way I'm reaching out to my fellow Corvette friends for help. I'm a long time mechanic and old drag racer. But I have met my match with this very complicated machine.

 

Check out the 350A fuse at the top of the battery.


Elmer

 

A fully charged battery is more like 12.6v. Make sure the battery cable clamps are all the way down and level, then tighten. Also make sure the small black wire is securely attached to the negative battery clamp and is not broken. If you loosened or removed any other cables around the battery, make sure they are reconnected and making good contact. One member had a cable that was a bit cocked and had trouble until the corrected the connection.

Check that you have good fuses on top of the battery - that is the same voltage on each side. The 350 amp fuse powers the starter and a few other loads.

Good luck!

Aloha!

Ron

 

Ron: Thank you for the informed reply. Now that you mention that black wire, the one on the left side of the two that go into the filter was pulled out. I thought it was to stop radio inference. and not that important. Also I did note a small drop in voltage on the 350 amp fuse link on the positive side of the battery. So I moved the cable to the next bolt forward to the front of the car. I will use my large battery charger on start mode, repair the negative side black wires and hope for the best. Would it be possible that one of the high voltage relays in the fuse boxes could have been damaged? I went thru all the fuses and they seemed okay. I looked for any that were associated with the starter, EMC and the BCM. Oddly the light on the shifter does not go on, but every other light seemed to work. On a happy note, I also have a low mileage C6 that has been trouble free for years. I will let you know what happens. Thank you very much, now I have an idea of what to look for. Best Regards, Colin in Hawaii.

 

Colin,

I don't know what you mean by filter. Do you mean the sensor on the negative cable? This is important for current sensing and charging.

All of the wires on the fuse block are POSITIVE. The other battery terminal with one big black wire and one small black wire is NEGATIVE / GROUND.

The fuse block on top of the battery has a 350 Amp 100, #1 100 A, #2 60 A, #3 100 A, and #4 100 A. Some of them may not be used in your car depending on options and coupe / vert. Voltage on each side of each fuse to the negative battery terminal should be the same as from the Battery Positive terminal to Battery Negative terminal. As you know, voltage drop means that there is current flow. There is also an aux fuse block UNDER the front fuse block. I have not removed the fuse block or even seen the aux block. I don't know what to tell you.

I did find some power distribution drawings - attached. Looking at the drawings, you should also have 12 V at the starter (just inside the right front wheel well).

I have had "new" batteries fail a quick test. I now insist that a battery pass the auto parts store quick test before I will accept it.

Don't know what to tell you - you are deeper into troubleshooting than I have ever been. There are at least 10 Chevy dealers with 30 miles of me - not all Corvette experts, but... And while I may have to cross the Mississippi River (on a bridge) to some of the dealers you win the prize for most difficult "drive" to a dealer.

GL

Ron

 

I hope you aren't saying that you bypassed the 350A fuse. That would be a VERY BAD idea.

 

Agree. NEVER BYPASS A FUSE.

 

Ron: I had the wrong wire in mind. The one that was disconnected was the black ground. Its connected now. I recharged the battery, its now 13 volts. Put all back to - gather. I thought I had it, all the dash lights were on. I went thru all the controls, the only ones that did not work were the fuel gauge and the stabile a track light was on. When I pushed the start button the dash went black again. I can hear the fuel pump running. So I guess its in the fuse box's some wear. I will keep on looking for the problem. What a mess. Will let you know what I discover.

 

No, it was just a fast test. Turned out it was okay.

 

Check voltage at starter before tearing into fuse box.

 

Use a test light of at least 4A to load the circuit when you measure the voltage.

 

Fuses can LOOK okay and be damaged. Replace any relevant, to be safe. Also, clean the battery connectors well and check where it is "mated" to the actual wire. I've seen them corrode internally at that point and drive every "expert" nuts finding the issue. And, that was only after a new cable was installed, with the old connector cut apart for inspection.. All the best.

 

I see you did the same thing I did cut out the factory 350amp fuse and used an aftermarket fuse in it's place. Much much better than having to replace the entire fuse plate. BTW, those 350amp fuses generally blow when you spun your main bearings or major engine failure occurs. It goes directly to the starter if anyone wonders...

 

No, I didn't have the problem. The picture that I grabbed off the forum was probably from your thread. You had a very helpful tip on how to replace just the 350 amp fuse. I save some of this stuff just in case I may have the problem later since the search function can be frustrating.

I need to figure out how to save the original info and give credit to the photographer!

Ron

 

Thank you for the reply. The battery fuse checked out okay without a load. I did a test by moving the positive cable past the 650 amp fuse with no change. My next step is checking all the fuses and relays connected to the starter. This all started when my one year old battery some how shorted out. I replaced the battery and that's when the black screen started. The car is like new inside and out. The cables look new. I'm by myself so I can't check the battery load when I push the start button. The battery has 13 volts without a load, but the volt gage reds 8 volts when the start button is pushed. There's a voltage drop some were. Man, this is the hardest fix I've ever run across. I appreciate all the the forum help. At least I'm not alone out hear in Hawaii. I also replaced the ecm. just in case.

 

Battery is connected directly to the starter with junctions at the underhood fuse block and the underhood aux fuse block. There are no fuses (other than the 350A one) or relays. You can load the circuit without pushing the start button.

The ECM cannot possibly be your problem and you could not have properly programmed the replacement. Re-install the original ECM and troubleshoot one problem at a time!

Edit: I suspect that your starter killed the original battery and is now trying to kill your new battery. If you want to replace something, try the starter.

 

Colin,

There's a lot of wiring and connections between the rear fuse block and the starter. Just for completeness, please check the voltage directly at the starter. The power distribution drawing attached to post #5 indicates 12V also at the starter. Apparently the starter relay / solenoid assembly is part of the starter itself. I haven't looked for the relay / control wiring schematics. I'm traveling again this week...

Ron

 

Dear Corvette forum friends: After 3 months of trying to repair my no start problem. My Chevy dealer relented and told me to bring her in on a flat bed truck.
Lucky for me the head mechanic is an old drag racing friend and knew what to do. With the testing equipment he found that the transmission computer had failed. Joy!!
So they also had ordered the tyranny adapter to change the old fluid. {$1000] wow. I'm picking the car up today 12/12. The bill is over $2000. Not real happy, but I had no other choice. I'm so happy to get my baby back. I have owned 9 Corvettes over the years ,the 2015 was my first that I bought new. And the first that I could not fix on my own. So if any of you folks have a black out control panel take a look at the tranny computer first.

 

WOW !!...3 months to get it fixed ??...was this a CAN network issue with the TCM ??...don’t believe a Chevy dealer wouldn’t attempt to look at the car...a code scan would have lead them to a network issue with a bunch of U (communication) codes. Without the right diagnostic equipment this would been hard for a DIY’er to diagnose without a scope...well at least you got it fixed !!

 

Hilo Hawaii drag racing. Turned 11.9 @ 120 MPH
I want to thank all the members who wrote to help me repair my C7. I drove it home yesterday, what a difference, runs better then when it was new. Remember my problem if your control panel blacks out. Regards, Colin in Hawaii.