Derek Adams

I purchased a C6 base LS3 in september from dealership, 39000 miles, Currently at 42200. Car ran flawlessly. I was driving to work on the highway at roughly 70 MPH and I had a whole lot of lights come on and went into limp mode.

During my lunch at work I went out to my car started it up, Put it in sport mode, shifted through all the gears fine(check engine light still on) got gas and it went away. Transmission was shifting fine yada yada, Well it came back on so I stopped at autozone and got the codes quick before it would go off again.

I attached a photo of the DTCs and a video of what exactly its doing while driving it.


Things I've tried:
Jacked car up looked for transmission wiring harness inspected to see if there were any wires bumping out of the connector(looked fine)

Reseated connectors under passenger seat and passenger floor near fuse box

Reconnected battery terminals.

4SUMERZ

There are a few things that have been known to cause this sort of issue.
1) Check all your spark plug wires. If one is off or loose, that will give all kinds of weird alarms.
2) The fuse box main (BLUE) connectors in the passenger footwell can become shifted if a passenger happens to push too hard on the floor board. There is not much gap between those connectors and the floor board. Unconnect the blue connectors, check for any bent pins, and reconnect using dielectic grease on the pins.
Some have used large pencil eraser as spacers to prevent that from happening.
I've added a PDF so you can see the connectors in question.



If you find the cause, report back so someone else can learn from your experience.
Thanks

Derek Adams

I'm going to try that right now. the pins under passenger side were a little twisted i tried fixing them the best I could but i'm gonna pull those two quick. Also took my vararam intake off just incase because that was my only major mod i have done to this car. Less trouble shooting the better.

Derek Adams

Unplugged both blue harness's replugged them in and checked the pins; they all look good to me. Even tried wiggling them around. I also cleaned all the grounds I could find. Btw it looks like someone had it marked with a white marker like they were going over all of this before and checked it off... assuming this was a reoccurring problem that dealership fixed before sale.

Derek Adams

When I have off again I'm going to have to pull my fender off and check the TCM out; make sure wiring is good. The fuse is not blown (10A) not sure if their are any others. I checked the back of harness near transmission visually looked clean and good but judging by pictures of everyone else it seems like the TCM module gets messy so maybe I need to clean that up and check pins and wires.

RicK T

Check this thread. It's been 6 years and I remembered the thread but I don't remember all of the details. There is a lot of info in it and both Bill Dearborn and Bill Curlee are still around so you may be able to contact them for more personal help. These "communications" problems are a bear to trace sometimes. Good luck.

https://www.corvetteforum.com/forums...-0n-06-c6.html

d.medic

How old is your battery? With the C6 it's the first place to start.

addictedtotrack

Did you mean ECM? Just asking because the TCM is in the transmission on the 6L80E. ECM is behind passenger side fender.

Unreal

Before digging in deep, battery and spark plug wires are common causes of this.

irok

with nothing but trany codes there's something amiss with your transmission

JerriVette

10 years of c6 ownership since new. 118k miles..

Every 27 to 36 months I get a multitude of messages in DIC of issues.

Always ends up being simply replace with a new battery. It's like $150 bucks give or take.....

All my DIC messages go away.

Change your battery to a new one first.

Works like a charm 99 percent of the time with forum members.

The voltage sent has to be good otherwise the computer sets off all these wild unrelated codes...

Take a piece of advice from a long time corvette owner who uses his corvette daily..

First change your battery..

It's not expensive and it's usually the path to happy motoring again..

Good luck

GaVette61

First check your plug wires, especially the coil pack side. It will take like 1 minute.

If you have done this and they are good then move to the next step.

Derek Adams

Alright so one thing i noticed the cluster lights are a lot dimmer now when car is running; windows also will not go up all the time or drop when i open door to avoid hitting the car. I pulled all the plugs and pushed them back on. Looked clean too. Before I do anymore electrical digging I guess I'll replace the battery. I personally think I have a short somewhere but worth a try!

Derek Adams

This is very depressing nice days and I can't drive it ;( but anyhow heres a picture of the bottom passenger side compartment, Looks like someone has already been here diagnosing the car? notice the 3 connectors marked off in white.

Caveman74

It might be worth a shot to unclip all of the harnesses and plug them back in. I had an issue with my OBD2 not working . I unhooked them and my port started working.

Dano523

Did you get a chance to pull the TCM connector and check it, the TCM pins yet?

As you should know, the TCM is behind the EVM in the passanger fender space.

Blue connector in the back is the TCM module connector.



But yes, with the white markings on the bcm connectors, does look like someone was in the car trouble shooting gremlins before you bought the car, and with luck, still just a electrical connection problem again.

irok

its an 09 auto car.TCM is in the transmission

BadAV

As stated already, replace the battery or at a minimum have it load tested. Low voltage does wrird things to today's computer controlled cars.

As far as your window problem, it sounds like you need to reindex the windows. You do this by running the window full up, continue to hold the switch up for a few seconds after it is fully up, release the switch, then pull the switch again like you are closing the window, hold it for a few seconds, then release it again. You have to do this on both windows; it's in the owner's manual.

Regarding the white marks on the connectors, this is a common practice in the assembly plants as an indication that a certain quality check or inspection has been completed.

Derek Adams

Ok so I havent touched car since; but I did go out and start it before I drove my DD to work; all the codes I was getting disappeared and could shift through gears in sport sitting still.(again)

But I did purchase another battery already put it in, Gonna eat dinner and take it out and see if it fixed the problem.

Derek Adams

Started fine, Drove fine, coming down over hill ding ding ding, lights on downshifted hard and car wouldn't even go over 10 mph and stuck at 1K rpm. Shut car off, turned back on. Sounded HORRIBLE like it wouldn't even wanna start.