A friend with a 2016 Stingray called me to check a no start condition. The battery was replaced and everything electrical works. When the start button is pushed the dash lights up then goes dark when pressed to start. The owner said before the battery was replaced the car would click like it wanted to start then nothing. Now when you push to start the dash goes dark and nothing. Release the button and the dash lights back up.

I suspect a starter but the car is stranded in a McDonald's parking lot and I could not see or access the starter to give it a rap to see if it would free up and engage. I checked a few of the fuses that are related to start and they were all good. Any relays that could be the cause? The car has around 60K miles on it. Thanks in advance for any inputs. The car will be towed to my house tomorrow so I can get the nose in the air.

 

That happened me when I replaced the battery in my first Stingray. So I disconnected the negative terminal cable and left it disconnected for 15 to 20 minutes. Then reconnected, making sure all components of the battery connections were in perfect alignment. And snug and tight. That is very important. After doing that, the engine started and I never had that problem again.

 

Battery connections can be the problem more times than you may believe.

So:

Once you get access to the battery, make sure that both battery cable clamps are pushed down, level, and tight. Make sure the positive buss bars at the positive terminal fuse block are in good mechanical contact and bolted tightly. Make sure that the heavy red battery cable is connected to the 350 amp fuse with good mechanical contact and that the cable ring is flat to the fuse before tightening. The cable should sit in a notch in the black tray under the bus. This cable should be at a right angle to the 350 amp fuse. See pic below:

Also verify the small black sensing wire is still attached to the negative battery cable clamp and not broken. This small wire has no effect on your current problem, but is important for correct battery charging. See wire attached at blue painted nut in the pic.

If still no joy, verify that the fuses on top of the battery are good - 12 volts on each end of each fuse referenced to the negative battery post. It is also possible for a new battery to be bad on the shelf or to fail at any time.

Also - a reminder to everyone to test operation of the metal hatch key and manual door releases yearly.

GL
Ron

 

You can try jumping terminals 30 and 87 of the starter relay...just remember to have the car in neutral or park when doing this and making sure you have the right 2 terminals...if the starter runs you have a control issue (terminals 86/85)...you will need a 12 volt test light to see if you have 12 volts from the starter enable circuit if the ECM and a good ground at G100...if a no crank when jumping 30 and 87 you should do a voltage drop check of positive and negative battery cables...if this testing is over your head seek out an auto electric shop in your area...checking the connections at the battery is a given so I will not mention that...I moved this to C7 Tech for further discussion.

 

Thanks. I repair F-15 and F-16 avionics systems for a living so electronics don't scare me. The car will be dropped off at my house today so I can do a better job troubleshooting since I will have access to my tools. Hard to pinpoint problems in the dark in a McDonalds parking lot.

Thanks to all for your tips, I will try all them and keep you posted on progress. Any other inputs greatly appreciated.

 

The cars electrical system is not quite the same as the 115/200 VAC 3 phase 400 cycle and 28 VDC stuff you work on but you should be OK...I ALWAYS start with checking the battery even if new for any electrical or driveability issue and going from there.

 

Will do. I did a cursory look see at the battery but nothing in depth. Where is the starter relay located that you mentioned in the other post.

The Corvettes are much easier to troubleshoot than the F-16. That thing is an electrical nightmare. The new F-15EX is a close second. Haven't been exposed to the F-35 yet, but it's coming.

 

Starter relay is in the underhood fuseblock.

 

Thanks. I found it on my car.

 

You will need to check all 4 terminals of the relay with a test light or lightbulb...this YouTube video is a C6 no start...this is the proper way to test.

 

Thanks for the videos. Just wondering how much alike are the C6 and C7 electronics.

I checked all of the connections on the battery and everything appears to be normal. I get 12.5V static. I'm solo today so I couldn't see how much of a voltage drop occurs when pressing the start button. I left the battery disconnected for about 20 minutes while looking over the connections. Car still won't engage. What I did find odd was I did not have to index the windows after I reconnected the battery.

The wonky part is only the driver's side window indexes correctly. The passenger side will index when you open it but then cycles indexing while open. You have to lower the window before it will close properly. I did the reindex procedure a couple of times but the passenger door is still wonky.

I took a pic of the under hood fuse box and want to confirm which relay should be checked via the procedure you laid out. Is it the grey one or the black one? They both have a pin 30 and 87. I need to make some leads tomorrow at work to use and get a helper. My neigbour is an engineer and good with a wrench and electronics so I'll borrow his help this weekend.

I have pics of what the dash displays when you try to start it. The mostly blank pic is what you get when you first try. After waiting about 30 seconds the next display comes up. If you try to shut power right away it keeps cycling. You have to wait 30 to 45 seconds to power down.

 

Now you talking about differences in electrical or electronics ??...for me these terms are 2 different things...electrical is the "muscle" and electronics is the "brain"...the OCV (Open Circuit Voltage" of the battery if lead acid should be 12.66 fully charged...AGM around 13 volts...the gray relay is the starter relay...all Bosch style 4 blade relays have 4 terminals...30/87 (load) and 86/85 (control)...30 and 87 are caddy corner across from each other as well as 86 and 85...the video explains how to check the relay...the C6 Run/Crank relay is on the bottom of the BCM...on the C7 it is next to the Starter Relay (#56).

 

C5 Diag - I appreciate all of your help. Right now I'm trying rule out either the "muscle" or the "brain". I'm leaving for South Carolina tomorrow so this project will sit until Sunday. If you think of anything else I need to check feel free to post or PM me. I will be monitoring the forum while I'm away. Again, thanks for your inputs. I was mistaken on the mileage. The car has 33K miles but they are rough miles. There has been some neglect over the years. I haven't seen any rodent damage but I haven't been underneath yet.

 

Hmmm.

So if you don't try to start it just hit the button what does it do?

Basically, if you want to be in "Accessory" mode (one click on an old keyed ignition) you just tap the button, the light will be Amber on the Start Button. If you HOLD for 5 seconds it will go into "Run" mode (engine off, two clicks on an old ignition), the light will be Green on the State Button. This is the same mode you are in after a "Crank" event which is done by putting your foot on the Brake/Clutch and hitting the button.

The reason I ask, is that in "Accessory" mode only a few things pop up. In "Run" mode, the car should have access to everything like its started.

Some modules use an "ignition hardline" (a voltage line either from the BCM or directly wired to the battery but through a relay controlled by the BCM). This is also called a Run/Start line, KL15, Ignition line, or Communication Enable line. Some things won't "wake up" unless they see this line. If you have a problem with this it can make the car non-functional.

Of course some of this can be diagnosed if you can do a full DTC read with a Dealer or 3rd Party Tool (not a cheap OBD tool, you need one that reads all modules).

 

The reason I say to do this with engine off is that it sounds like this is more than an engine issue. If you can't even get all the screens and modules to boot up in "Run" mode without the engine on, I'd not even worry about the engine not starting, yet. There is something wrong greater with the car.

When we have prototypes that don't work that's the first thing we do. Put the car in "Run" and read DTCs from the whole vehicle. Then see what shows up. You diagnose enough cobbled together development vehicles and you start to become an expert on all the crazy stuff that can fail for no reason whatsoever.

 

If you push the start button without trying to start it, you get the blank screen as shown in the pic. If you do nothing else and wait 30 sec it then appears to be in normal accessory mode as the radio works, windows work, dash lights up as shown in pic, etc. If you push the button again it does not shut off. It cycles again. You have to wait another 30 sec with display lit and then push the button and it will power down. I have a 2017 Z06. My car works normal, this one does not. If you try to start it with foot on brake, you get the blank screen and no start. You can hear the fuel pump engage but that's it. I have not been able to get the car to run. Somewhere the signal is not telling the car to start. The owner drove the car on Tuesday roughly five miles to their destination. When they were ready to leave all they got was a click, then nothing. A new battery was installed but no help. I have checked all of the battery connections and everything is in place with no corrosion. I do plan to charge it up when I return on Sunday as it currently sits at 12.5V and I have been using battery power to to troubleshoot. I have not checked any of the wiring under the car or at the starter yet as it didn't get to my house until just before dark. I'm on hold doing anything else until Sunday but any all suggestions are welcomed.

 

So if you hold for 5 seconds and the switch turns green everything boots up fine and stays booted up?

That would mean then there is some amperage issue because in "Run" mode engine off, the car doesn't pull that many amps.

To test if the system has a resistance issue (basically to engage a load) turn the steering wheel, if it has assist (I will need to check this when I get home) then the steering system should try to draw a lot of power. If the car voltage crashes then you have a wiring problem.

The steering system after the starter and the engine fan is the highest amp pulling device, it can pull 110 amps.

 

We're saddened to hear of the no start concerns and dashboard difficulties your friend is currently having. When you can, please have your friend email us at socialmedia@gm.com so we can help provide support in exploring this matter further. Additionally, please ensure they include "Tally Ho/Corvette Forum" in the subject line of their email. We thank you both for your cooperation.

 

I had a chance to look at a few things you pointed me towards.

1. When testing the four points on relay 54 only pin 30 lights up.
2. When jumpering 30 and 87 there is nothing.
3. With all of the on/off I managed to run down the battery to 12.0V so I have it on charge until tomorrow.
4. With the DMM leads on the battery, when pushing the start button, the voltage dropped about 0.2V.

I'll be back at it tomorrow once the battery is at full charge. If there is anything else I can check let me know.

 

If the run/start relay fails some of the components won't come on in "Run" mode either. Run/start is like a "bus" in that many things use it, not just the starter.

Like the power steering which wakes up on the run/start line as well. Not sure if there is only one relay or multiple though. Sometimes there are multiple. I can look at the wiring diagrams in the Service Manual.