Until 6 days ago my 2007 Vette has been very reliable, it has had an appetite for batteries and has had 4 replacements in 8 years but that is its only issue until now. The car is mostly stock with only 25,000 miles on the clock. It was purchased from a member on here and has only a skip shift eliminator and Corsa cat back for mods.

It all started like this: I got in the car, pushed in the clutch, hit the start button, dash went dark, check engine light stayed on but no cranking at all. I waited and the dash came back on so I hit the start button again, same thing. I thought my key fob battery was dead so I put it in the slot in the glove box, no luck, same result.

I hooked my scanner up (Generic Bluetooth interface and Torque app) to the car and it showed P0606, faulty ECM. I cleared the code, unhooked the positive battery cable,hooked it back up and the car immediately fired up. All seemed fine.

I went to go to work the next day and same issue but with no code set this time. That evening I changed the BCM relay after doing a bunch of internet searching and seeing this exact issue from a bad realy. The car immediately fired up and I was able to restart it 10-12 times, also no codes were set. I thought all was good again.

Went to go to work the next day and same thing again, only this time I had a whole series of clicking relays from the underhood box. In addition a number of warning messages appeared on the dash, service fuel system, reduced engine power, etc.

I gave up on it until today. As usual the car wouldn't start but then very strangely the lights got extremely dim and then the doors wouldn't open, exactly as if the battery was dead. I put my voltmeter on the battery and it only read 9.05 volts. At this point I was sure I had the issue solved, I pulled the battery and took it to Napa, they confirmed it was smoked, they replaced it no questions asked as it was only 4 months old.

I brought it home, installed it, and the problems intensified. Now I had no cranking, and the CEL was not coming on at all. I hooked the scanner up (HP Tuners) and it said it was unable to connect, I attempted to scroll through the dash display for oil pressure, engine temp, average fuel economy, etc and everything showed XXX as though the ECM was dead.

I walked away from the car for an hour, came back and sat down in it, turned the ignition on but did not attempt to start the car, however the CEL was now illuminated! I was immediately able to connect HP Tuners. I pushed the clutch in, hit the start button and it lit off immediately and idled perfectly. It started another 5-6 times no trouble.

At this point I am thinking bad wiring harness so I start shaking the harnesses from the fuse block down to the ECM, I pulled the passenger side front tire and got access to the ECM and shook the hell out the harness, I was unable to induce the problem.

I then checked every ground I could find, all were clean and tight. I checked the battery cable connection to the starter solenoid and it appears perfect although I have not physically removed the starter to check it but there does not appear to be any melting.

I am honestly leaning towards a bad ECM but that just seems so unlikely, how often do they really go bad?

Short list of what I have done:

Swapped BCM relay with a known good working one
Swapped starter relay with a known good working one
Replaced battery
Checked every ground under the hood, all are clean and tight
Checked positive cable to start solenoid, looks good and not burned
Rattled and shook fuse/relay block, unable to induce problem
Shook and pulled fuse block to ECM harness for 10 minutes, unable to induce problem
Verified ECM connectors are properly installed and no moisture intrusion or mouse damage
Checked every harness I could get my hands on for mouse damage, none found

Can anyone offer some advice before I swap ECM's??

 

Doesn't look like you have a scan tool capable of reading anything more than P-codes. Neither the generic nor the HPT will read anything but P-codes. You need a more powerful tool to read any B, C, or U-codes. Something like a Tech II. It would be interesting to see if anything is reported in the U-code range. U-codes report the communication and health of the modules in the car that utilize the CAN bus. A module that might have an intermittent corruption can cause an interruption in the Can Bus serial comm.

By what you're describing at one point (relays clicking, etc), is definitely a battery that has fallen below 11.8v threshold. Something is going on with the car killing batteries. 4 batteries in 8 years is not right.

Separate and aside from that, and I hate giving this advice because it sounds like a "fix'all elixir", try doing a hard reset. Hard resets drain all the capacitance out of all the modules and forces them all to reboot on startup. Disconnect the negative battery cable. Make contact with it to the positive cable. Hold this for 15 minutes. Then reconnect the negative cable. Try a restart. If you've never done a hard reset, don't worry, as long as the negative cable is disconnected, with nothing on the negative terminal, you can safely touch the positive cable/terminal. If it feels safer, then disconnect both cables and touch them together for 15 minutes. 15 minutes is overkill, but will guarantee all capacitance is drained.

Next, by at least one of the symptoms, you could have a bad start switch. This is the dash start switch. Here too, I am not an advocate of replacing parts until the problem is fixed, but with everything you've done to date, this is one of the few major components in the start/run chain you haven't mentioned.

 

Low battery voltage glitches the hell out of the system, so most of the time, just a mater of un-connecting the full charge battery long enough to allow the systems to voltage bleed all the way down, and when you reconnect the battery, it will reset all the modules to solve the problem most of the time.

As for bad battery in a few months, could have been a defective battery from the start, or could be a problem in the charging system not fully charging the battery back up or the car has a parasitic draw problem that is drawing the battery down to far when the car is off with a module or two not going into sleep mode , and causing the very short life on the battery instead.

Voltages check points listed in below link,
https://www.corvetteforum.com/forums...intenance.html

 

Boy this is a familiar story. Had the same problem. Not the battery issue but the warning lights and random no start. Changed ECU, BCM. checked harnesses and connectors, no luck. After going thru hundreds of threads about this issue I checked one of the things that a number of members mentioned that I thought was just plain silly, LOOSE PLUG WIRE !!!!! Never thought that would be an issue and I had no misfire.
Lo and behold the number 3 plug wire was loose in the coil. The boot was tight but the wire didn't have a solid connection. Coil was probably arcing to the wire so the cylinder still fired. Cleaned the connector reinserted into the coil. Problem has not reoccured in several weeks now.
Appearently the emi is enough to mess with the can bus.
Thanks to all the members who posted about this issue

 

Thank you guys for taking the time to respond and try to help!

I spent all of Saturday and part of Sunday trying all the solutions mentioned here and others I found online.

Absolutely nothing worked, I kept thinking it was fixed then would come back 45 minutes later and same problem! I must have attempted to start the car at least 200 times, I had success probably 50 times. How discouraging!

I gave up and ordered a Chinese Tech 2 clone. It should be here soon and I will get to the bottom of this problem. For $274 to my door it seemed like the cheapest option, I hate throwing parts at a car, and I HATE taking the car to the dealership for anything electrical. It is almost a license for them to steal on an issue like this.

More to follow, if anyone has more ideas I will gladly listen and be thankful for the input!

 

Yes I would agree. You can't take this problem to a dealer, you'll go to the poor house and still have a car that doesn't run.
The tech 2 is the way to go.
I'm reasonably sure you'll get a b 1000 ( I think ) code. CAN bus communication .
Then finding the culprit becomes the issue
GOOD LUCK
keep us posted
we'll try to help you thru it

 

Just a quick update.

I got my Tech 2 clone and it works perfectly!

A lot of my electrical gremlins were being caused by the old AND new battery having low voltage. Once the new battery was fully charged the vast majority of the electrical gremlins disappeared.

However, the car still has random bouts of not starting and lots of clicking relays followed by a REDCUED ENGINE POWER message and a code of P0606.

I am really leaning towards a faulty ECM.

When the issue happens all modules report as present on the Tech 2 but it still won't crank. More telling however is the the crank request shows up but the starter relay never shows as operational on the Tech 2, it simply doesn't apply the voltage.

I am obviously not a Tech 2 guru so if anyone wants to lend some advice it would be much appreciated.

I think I may just spring for the $150 ECU from e-bay and see what happens.

Any other input?

 

Is the ECM showing start, then run commands, but no voltage to the starter relay in the fuse box when you check it with a meater. If yes, then check the engine fuse box lower box, and ECM connector for bad connections between the two.
If the starter relay connector in the fuse box is getting power, but the starter solenoid is the problem with lots of clicking at the starter, then new starter solenoids are dirty cheap to replace on the starter,

If it is the ECM, then it a cold solder joint that should be a snap to resolder on the ECM board isntead. Hence new ECM to the car (even used ecm) would need to be SPS flashed to begin with to the car, then will still need to tech II a lot of releans as well (crank,timing.throttle relearn).

 

I didn't have the same symptoms as you did but did have a bad ECM - see thread below
Bad ECM

One thing before getting an eBay ECM - since you have HP Tuners you will be able to flash the ECM - but you need to get an ECM out of a 06-07 Corvette.

I got a junk yard ECM from a pick-up truck and re-flashed it with EFI Live but I would get P6060 and reduced engine power with that ECM.

You need to get an ECM out of a 06-07 Corvette because the ECM's operating systems are only compatible in a certain year range see the table in the link below:
Compatibility Reference

If you are able to find a ECM from an 06 or 07 Corvette you should be able to flash it - then you will have to do a theft re-learn where you have to push the start button but don't start - wait 10 min, then off 2 minutes - key on 10 min, then off 2 and key on 10 min then off and that should re-learn the theft module.
After that you just have to do the crank sensor re-learn with your Tech 2 and you should be good to go.

Hope this helps

 

TIS2000 SPS for immobilizer relearn solves the thief relearn problem in less than a min, and you can flash the replacement ECM with the correct firmware for your car in about two mins as well.
From that point, then you can use HP tuner or HP live to flash back in the custom tune next, since there are only portions of the ECM firmware that HP tuner or EFI live touches to reprogram in the OEM firmware during a tune instead.

 

Did you check the well known ground wire and post on the starter? Could have a bad coil on the starter. Had similar issues on my 2008. Replaced starter, everything worked. The coil on the starter is close to heat sources. I would check the starter before replacing the ECU. The nut holding the wire sometimes backs off or the casing around the post breaks.

 

Keep in mind, even if you reflash a new ECM with a Tech II, that ECM will not be the same as the one you registered the car with when you licensed HPTuners. Order of operations here is important. Do not attempt anything with HPT until after you've done all the GM service programming or you'll be wasting money on HPT credits. I made this mistake. I relicensed HPT on my car on a new ECM which turned out to be faulty. Got another, then did GM service programming, and pow, HPT license was no longer valid, had to pay again. In the end, I payed 4 times in total for my HPT license all for the same car and same VIN. Make HPT the last stop here, otherwise you'll be paying twice. Actually, you'll be paying twice anyway, just don't pay 3 times.

 

If you call HP tuner and let them know that you had a ECM go bad, had to replace it in the car, they will credit you of the licenses credits to re tune the car with the new ECM.
Hence if you go to the tune file and pull up calibration details under the edit tab, it going to pull up the Vin number that the tune was original flashed to the car,what you paid for on the original credits, and this will still match the same on when you have to re-after market tune the new ECM as well. Hence vin number will be the same for the new ECM, but serial number of the New ecm will be different, and what causes the needed to pay for new credits unless you call HP tuner for the original credits to be transferred to the new ECM.

As for tuner, if you are having someone else tune the car, then, may still get hit with a small tuning fee, since once they have the Credits switch to the new ECM so you don't have to pay that again, they need to use the old tune file to manual go back in and change the values on the return of the new ECM (cant just reflash in the old tune file, to the new ECM).

But yes, need to SPS flash the ECM first to the car, do the relearns with the tech II, then you can go back in with HP tuner to after-market the tune afterwards.

 

When I called hptuners to ask about it, they just said it sucks to be me. Thanks for the extra money.

 

 

Would have just hacked the new ECM to change its serial number to the old ECM's Number to solve the problem then.

 

I do believe I have fixed my problems!!!!

Dano523 and I corresponded via PM about cold solder joints. Following his advice I pulled my ECM apart and did indeed find 3 obviously cold solder joints on the board. I touched up every one I could get to but unfortunately it didn't cure the random no start situation. But very special thanks to Dano523 for his help!

In desperation I gave up and ordered an ECM from an E-Bay seller named spareecm. It arrived this afternoon already programmed with my VIN. On installation I immediately noticed the drivers door opened quicker. I know this sounds crazy but the very first indications I was having trouble with the car was a significant delay between touching the finger pad in the door and having the door pop open. I thought that was a switch going bad in the door, I think now that it was related to my computer problems. The door pops instantly now when I hit the pad.

I did the crankshaft relearn with my Tech2 and the CEL went out immediately. The car has now started and run perfectly at least two dozen times. I am taking it to work tomorrow morning. If it starts after sitting overnight I will know it is fixed. But as of right now I am going to say she is ready to rock again.

Thank you so much to everyone who has offered their advice, it is ALL greatly appreciated!

I will report back tomorrow to let you guys know if my car really is fixed.

 

SUCCESS!!!!!

My car is back to its old self now. It started and ran perfectly multiple times today. I went to work, the bank, lunch, grocery store, and home. Not a single issue, it is fixed for sure!

I don't know what caused the ECM to die but it certainly manifested itself in an odd manner, regardless it is fixed now.

I would definitely have have an issue if I didn't have the Tech2 for the crank relearn. You can't simply turn the CEL off for that, it HAS to do the procedure or the minute you clear the code with a basic scanner it comes back.

I learned a ton about this car from this issue, while it wasn't fun it was quite rewarding to know that I fixed it myself.

Thanks again to everyone who offered their advice.

Man was it fun to be out letting this thing rip again!

 

No worries, and post a couple photo's of the old ECM board both side to see if any other cold solder joint are blatant that you may have missed.

Hence if not a header pin (which is the problem most of the time), then it could be one of the resistor end joints, or even a CPU pin that has a bad solder joint instead.

 

that have been done long before. That number has nothing to do with the identification hptuners uses to know what device it's talking to.