carnut08

My 08 C6 has been trouble free since I bought it new 51,000 miles ago. Yesterday the check engine light came on. I immediately pulled over and checked the oil and coolant levels. They were full since the car had just been serviced only about 60 miles before. The car ran fine and since I was only a few miles from home, I went ahead and drove on home.

The check engine light stayed on, but along the way the dreaded "Service Active Handling" notice appeared. When I got home I removed my Window Valet and connected my OBDII/CAN Code Reader. It went through the normal protocols looking for a connection, but never could connect after repeated tries. I got a second Code Reader of a different brand and it couldn't connect either. I replaced the Window Valet and it works perfectly, so the connector in the car obviously works.

The car starts and appears to run fine. The check engine light comes on every time I start it, but the Service Active Handling message now just comes on occasionally.

Does anybody have experience like this? Any ideas what might be going on? Help!

ClothSeats

It seems like you need to find out if the problem lies with the OBDII port or your reader(s). Maybe you could take your car to an auto store that offers free code reading service and have them give it a try. You know their code reader works, so if they can't connect, then you know the problem is with your OBDII port.

carnut08

Thanks for the suggestion. Both readers do work and both connect and light up. They just can't get a reading.

C6_Racer_X

Inspect the back side of your OBD-II connector socket. Sometimes one (or more) of the wires will get pushed out the back side and not make contact.

carnut08

Thanks for the suggestion. The back side looks fine and the front side has the correct pin connectors

BadAV

Have you checked for a blown fuse?

C6VetteLover

Without a manual in front of me to confirm, it's often an accessory fuse or the cigarette lighter fuse for the OBD port when you can't connect.

madmatt9471

Some of these just might help you with your issue:
OBD2 Problem
https://www.corvetteforum.com/forums...2-problem.html
https://www.corvetteforum.com/forums...onnection.html
https://www.corvetteforum.com/forums...t-working.html

C6 Data Link Communications Description and Operation
http://www.teamzr1.com/ubbthreads/ub...at&Number=2877

Loss of High Speed GMLAN Communications
http://www.teamzr1.com/ubbthreads/ub...at&Number=2540

HIGH SPEED LAN Diagnostics / Remembering Ohms Law
http://www.teamzr1.com/ubbthreads/ub...at&Number=2772

Thanks,Matt

carnut08

Thanks BadAV, C6VetteLover, and madmatt9471. I'll be following all your suggestions and report back if anything solves the issue.

carnut08

Well, I've followed all the links and suggestions and the problem is still there. Neither OBD/CAN readers can communicate with the port. The fuses are all good, and as I said in my original post, the C6 Corvette Window Valet - SouthernCarParts.com, which plugs in and stays in the OBD2 port unless the port is being used for diagnostics, functions normally. This means to me that the port functions at least enough to communicate with the BCM and control the windows with the fob.

FYI, the Window Valet has been in use since the car was new.

I would really appreciate hearing from someone who has had this problem and knows the solution. Surely I'm not the only one???

BadAV

@Dano523 any suggestions to help the OP?

carnut08

Finally! After much searching and experimentation, here is a list of the things that lead to success:

• Removed and checked REAR FOG/ALDL/TOP SWITCH fuse - fuse OK, no change in connection error
• Disconnected the battery for an hour - Check Engine light was out on restart - no change in connection error - Check Engine light came back on.
• Removed and checked GMLAN RUN/CRNK fuse -fuse OK, but once re-inserted the OBD2/CAN reader communicated!

The OBD/CAN reader reported three engine codes. I didn't write them down but they had to do with issues with inlet temperature and mass airflow problems.

I erased the codes and will need to road test the car to see if they return.

I mentioned that the initial check engine problem happened shortly after the car had been serviced. Gues what was serviced - the air filter was replaced! I'll report back after a road test in a day or so.

Thanks again to all who tried to help me. This forum is awesome!

carnut08

The road test lasted just long enough to clear my driveway and the check engine light came on again. At least the code reader continued to work and again a series of codes pointing to intake issues appeared, but they were not the same ones as before.

Because the car had just been serviced and part of the service was to replace the air filter, I again poked around to see if perhaps there was something visible that could be causing the problem before dismantling the assembly. Yep! There is a plug on the driver's side of the assembly that was left disconnected. The wiring harness for that plug was placed so it wasn't obviously disconnected, so I hadn't noticed it earlier. Once plugged in, the car runs fine. I cleared the codes and did an extensive road test and all appears to be OK.

Bottom line - That disconnected harness caused the BCM and who knows what else to have a complete hissy fit that was very difficult to diagnose and remedy.

Sloppy service work cost me endless hours of frustration and the loss of use of my favorite car for a week. Without this forum and Google I imagine that I could have spent untold $$ to have the problem 'professionally' diagnosed and repaired.

ApexClone

So your MAF was left unplugged. Glad it turned out to be an easy/cheap fix at the end.

hdrider1

Who did the service and left your MAF unplugged? I hope you gave them appropriate feedback so maybe they can be alert to the issue on the next person they service.

carnut08

I did report the issue, but no way am I going to flame those guys. We're all human and over all they have been excellent over many years.