The car is a 2010 GS convertible, completely stock as far as I know. I've had the car less than a year. I've put 5K miles on it in that time. I thought I had the problem fixed. I started documenting the issue the first time it happened here: https://www.corvetteforum.com/forums...5&postcount=86
Today, my wife and I drove from Mesa to Tucson so that I could get a Global Entry Interview (Phoenix was booked until Oct). The car ran fine all the way down (128 miles door to door, all but 6 miles on the freeway). In Tucson I parked in covered parking ambient temp was about 98-99 according to the car. Total time parked was 1 hour. We drove about a mile to a small restaurant for lunch and I parked in the sun, car reported about 101 or so. Spent about an hour in the restaurant and when I tried to start the car it started and then immediately the engine died, with reduced engine power and check traction control in the DIC. Another symptom is that the car will not shut off, it will only go to accessory mode or on (not running). I disconnected the battery and left the hood open for 10 minutes, both positive and negative, reconnected the battery and the car was in the same condition, thinking it was in accessory mode. I then disconnected the battery and left the hood open again, and we let it sit for 30 minutes. I reconnected the battery, the car started and ran OK. No messages in the DIC. I drove home without an issue. Now the real troubleshooting will start.

I will check with Tech2Win tomorrow to see if there are stored codes, I know the battery cables are tight at the battery, I don't know about the other end of the cables yet. The oil, coolant and transmission temps never get excessive, at least I don't get temp warnings. I do have a question for the gurus here: Do you know what the underhood temperature might get to in 110 ambient, city driving with a stop every mile or so for a traffic light, speed 45 to 55 when not at a light, AC on. I checked my oil level yesterday after returning home and could not hold on to the dipstick without some protection for my hand.

I am going to make an appointment to bring the car to my local guy, yes the same one that assured me it was the battery the first time this happened but this time I will have some very specific questions for him and very specific areas I want him to check I know other people seem to have solved the problem by replacing the ECM. Is there any way to test the ECM and BCM either in or out of the car or is this solution just a WAG? I guess I am asking for help with troubleshooting suggestions, battery cables, underhood fuze block connector, BCM connector, ECM connecctor etc. what else? Thanks in advance for any help you can give.

 

Maybe I missed it but assuming you do have a new battery correct ??
NSF

 

Yes, I did replace the battery.

 

Here's an update. Today, car @ 65MPH ambient temp 114, run time about 60 minutes total. I had driven about 30 minutes in city traffic parked for an hour in covered parking then restarted and drove about another 25 minutes in city traffic but got on highway and went to 65 speed limit. This lasted about 4 miles with radio on, A/C on temp set to 73. Car shut off while cruising, luckily I was in the right lane. Indications: reduced engine power, Traction control system malfunction DIC messages. Pulled over, shut off A/C, shut off radio, shut off ignition (this time the car actually shut off), turned on flashers, lowered the windows and called wife. Opened the hood and waited for her to arrive, about a 40 minute wait then attempted to start the car. Car started but the check engine light stayed on. Drove the 3 miles home check engine light stayed on. Shut down connected VCX Nano, started tech2win, and started car, check engine light was on. Got the following codes: EBCM C0242 PCM indicated TCS malfunction, ECM P0601 Control module ROM, VCIM B1001 Option Configuration error. I had not had to car to the technician yet.
Anybody???

 

 

Some research on the web gives this:
EBCM C0242 PCM indicated TCS malfunction
Possible causes
Faulty Electronic Brake Control Module (EBCM)
EBCM Harness is open or shorted
EBCM Circuit poor electrical connection
Faulty Engine Control Module (ECM)

P0601 is defined as Internal Control Module Memory Check Sum Error. This refers to a fault in the internal control memory of the PCM.

Don't know about you, but at this point in my life, I'm tired of trying to diagnose and fix problems where the technology has moved way beyond my pay grade. At this point, I would be finding a shop who would guarantee that their diagnostics and proposed fix would solve the problem, so that if it didn't, you either get a refund, or they continue to fix the problem without further charge to you. At least one GM dealer will do this who is local to me and will warrant their work and parts. This is the purpose of the diagnostic service charge that GM charges, and which everyone whines, moans, and bitches about. Regardless of what they SAY, get it in WRITING. Just my .02

 

Thankfully there're several codes, in the worst cases I recall there were no codes set so WTH to start troubleshooting a genuine nightmare.
Ideally you've access to a crackerjack electrical tech, it's crucial tech knows these codes in case they disappear.
Methinks issue can & will be resolved through these codes.

G/L, update please.

 

Thanks, yeah I have the service manuals for the car and what you quoted was also in the manuals. I know I am not knowledgeable or experienced enough to diagnose this issue. I am in the process of locating a shop with good / experienced diagnostics techs.

 

I do hope that the codes can help lead a tech to the correct fix. I really hate shotgun troubleshooting, that usually just leads to very expensive parts replacement that only fixes the problem after much money is spent.
I will update as things progress.

 

crank pin sensor?.........gets too hot cuts off, when it cools down it runs again..........

 

 

The technician has diagnosed that I have a bad ECM. They will be replacing it on Monday. I asked a quick question in a separate thread about keeping the old ECM. I think I'm going to but the seller of the ECM wants a $75 core charge. Still thinking about it.

 

 

I'm hoping it is the ECM and this is not just the beginning.

I had another thought though. I thought that reduced engine power meant the car would stay running, we just didn't have full power. In my case, when I got the reduced engine power DIC message, the engine shut off. I was lucky that I could pull over. The owners manual does not mention that the engine might shut off when that message appears, quite the opposite.

 

 

That didn't even cross my mind. I would have thought that if it's bad spark, bad MAP sensor, bad throttle body etc. there would be additional codes stored. There were not any codes other than the three I mentioned earlier in the thread.

 

 

From the research I've done, in this forum and around the web, it seems the C6 is very sensitive to low voltage and high ambient temperatures. With the underpowered alternator, city driving, very high ambient temperatures in the southwest etc. I'm not surprised. Computers in general are sensitive to voltage fluctuations, low voltage etc. That's why PCs, even laptops have fans. I don't know the airflow over the ECM, but seeing as it's tucked away and protected somewhat from water I can't see how it gets much airflow. BCM is under the passenger floorboards so it doesn't get any. I would think the Chevy design engineers took the environment the parts would live in into consideration, but when you have poor manufacturing quality control (cold solder joints and the like) you are going to have issue with reliability. I have to think the issues would have happened earlier in the cars life like when it was still under warranty if they had been driven more but then I wouldn't have been able to buy an eight year old car with only 10K miles on it. You can't have everything. And again my car is eight years old. Cold solder joints will fail for a number of reasons one of them being operating cycles, heat it up when operating everything expands, turn it off everything cools down and shrinks, eventually a bad joint will crack and fail. I've decided to keep my old ECM. I don't know for sure if the ECM replacement will solve my problem, I hope it will, but I've decided to keep my old ECM to open it up and see if any solder joints have failed. It may not be cold solder joint problem. Components can also fail, diodes, capacitors, ROM chips etc. are all possible culprits. I'll have to wait and see. Sorry, I'm rambling I know. I'll stop now.

 

 

I got the car back from the repair shop with a new ECM in it. It appears to be operating OK, but I'm holding final judgement until I can operate it in the conditions that caused the failures before.
I did keep the ECM they removed. I want to open it to check the boards. It appears to be easy to do, the lid is held in place by four torx screws but it also has what appears to be a thin layer of silicon as a gasket to keep crud from the inside. That stuff is tougher than glue. Any suggestions of how to pry the lid off without bending the crap out of it?