First post here. We have an '09 C6 with approximately 25,000 miles and is completely stock.

Occasionally the tire pressure warning combined with the TPMS light (looks like an exclamation mark with a ring around it) will deliver a bogus message . The DIC claims the "Right Rear" tire pressure is 17psi. However, when using a tire pressure gauge, all the tires are 32-33psi.

Sometimes one tire will randomly go to 0psi, then jump up to 50psi, and then go back to 32 psi within one minute. While the actual pressure in the tire is really 32-33psi. Funny thing is, this only happens when close to parking lots with shopping cart anti-theft systems, cell phone towers, or other sources of EM interference. It never happens when at the dealer.

Then today, the hand brake warning came on even though the handbrake was not pulled up. This happened on the highway! After restarting the engine, the warning went away by itself.

Now the strangest part is that the trunk opens by itself with nobody touching the FOB; sometimes this occurs in the middle of the night after the FOB has been put away! Also the alarm will go off by itself as if someone pushed the panic button on the remote but the FOB is sitting on a desk, untouched.

Any ideas what this could be? Body Control Module? RCLDR Module?

Any help would be greatly appreciated.

Thanks!

 

Welcome Aboard!

Sometimes a dying battery or loose cable will produce all sorts of weird problems. Your battery should still be good, but...

Still under warranty? Dealer can read the codes and maybe even fix it free.

 

I would second the dying battery or loose cable. I thought I have something similar but it was because my fob was in my left pocket and everytime I got out it the bolster was depressing the button

 

Got something in your pocket that's pressing on your fob??

 

Nope, as stated in the first post the FOB will be sitting on a desk when this happens. This is not the only problem.

The tire pressures will randomly jump from 32 to 0 to 50psi when driving at a steady speed on the highway, resulting in "Tire Flat" and "High Tire Pressure" messages one after the other.

And on one occasion, the windshield wipers sped up by themselves without touching the wiper speed setting.

That and bogus warning lights coming on and going away after a few seconds.

 

I would agree you need to have battery voltage checked first. Low voltage can cause all sorts of problems. Might want to disconnect the battery for 20 min and then reconnect it, this will reset the computers.

Hope it is as simple as this. Good luck!!

 

The battery voltage is 13.8 volts after the car has been sitting for a while. Once the car is started and driven, it goes up to 14.2 volts. I don't see corrosion on the battery terminals.

Today the message "Service Tire Monitor" came up on the DIC. After restarting the engine the message went away and has not re-appeared.

We would like to take the car to the dealer, but getting the problems to show up in front of a mechanic would be hard. This only happens in places where there are high EM fields or interference.

 

Sounds strange, but I can help you with the tire pressure...

The TPM's batteries are most likely dead and will need to be replaced. You can call a number of vendors here for new TPM's. Those little batteries will not last forever!!

I am unsure whether the windshield wipers have a sensor to speed up as the rain comes down harder. I know my Caddy does that. (I dont drive the Vette much in the rain). If so, check to see if something is blocking the sensors.

It doesn't sound like there is anything major going on here. Take it to a reputable Corvette mechanic and I am sure the minor issues will be solved!!

 

Thanks. Since "Service Tire Monitor" just came up on the display, I think one or more of the sensors need to be replaced. Instead of jumping from 0 to 50 psi, it now goes from XX to 32 psi randomly.

I'm hoping electrical problems like this can be easily solved, since we hope to keep the car a long time. On another note, this was the last '09 on the lot (we bought the car new), and on the day of delivery the dealer had to jump the battery to get it started. Strange because he supposedly had it running the day before and that morning to do the prep work. I am thinking something might be draining the battery in the car?

Car is a daily driver, so it gets started up every day.

Will take in for warranty service and see what they say.

 

My opinion is for you to get the electronic brake control module checked....it sounds simplamatic of that...obviously its hard for me to tell without being at your car, but I would definately take a look there first. It may be a body control module....but the brake is the one that tips me off torwards what i mentioned......Good luck & hope this helped!

 

Started the car to drive to the dealer. Problems are gone!

I am thinking I will have to record the issue with a video camera and show it to the dealer because OnStar cannot detect any error codes and the dealer will not be able to see any stored codes (there are none). According to the owner's manual, the tire pressure warning resets itself at the next ignition cycle, and only reoccurs when there is a problem. As for the hand brake, it is definitely off because the car moves in neutral.

I guess daily driving (15-20,000 miles per year) wears down electrical components, relays, and sensors? The engine bay seems too cramped and hot for all those electronics and we all know capacitors can fail from excess heat.

 

Low batteries in tire sensors - maybe. Ever have a set of tires changed yet? Maybe sensor damage.

Brake Warning On Light - Check fluid level, could be brake pad time, switch in emergency brake handle can be adjusted. Bump in road perhaps?

Trunk Lid/ alarm in the middle of the night. Make sure you know where ALL your fobs are.
Low Car battery - best guess.

Windshield wiper speed - no guess.

So a bad battery could be all of the above items. Best bet is to get a new battery - might be prorated cost discount.

Also water intrusion. Do you wash your bay? Check all your fuse boxes and computer control connections.

 

At this point I have scheduled an appointment with the dealer and they will look at it. A rep from Chevrolet Customer Service said it could be the BCM or other modules, so I hope this problem can be resolved.

 

BCM seems to be the common link, or possibly something related to it (crimped wiring).


Can you say when this started, as in, what changed between it not happening and when it started doing all this?

(Saw your previous post...good call to go that route...good luck, and keep us informed.)

 

I don't really remember when all this started, but I think this is moisture related, as most of the problems come up when it is raining outside. The car has been fine otherwise [mechanically], and we haven't had to replace anything yet...

 

Today the problems came up again so I took a picture of the dash with a digital camera. The emergency brake light is on but the speedometer shows 50MPH, so obviously something is wrong. I spoke to a higher level tech on phone support and he definitely thinks it is the BCM now. Dealer is suposed to look at it next week, I have the picture of the dash and the "Service Tire Monitor" message too.

 

Update: Problem Solved!

We took the car to a Cadillac dealer (which also services other GM vehicles) and they fixed everything for free under the factory warranty.

It turns out there was some corrosion on the battery terminals, so they cleaned the terminals and sprayed the contacts with electrical contact cleaner. The service tech said that whenever the battery gets low, strange things can happen with the electrical system. Now the battery reads a healthy 14.3 volts at idle and 14.4-14.5 volts while moving.

Also, one of the tire pressure sensors needed to be replaced. The dealer did the TPMS reset/relearn procedure and found that the right rear sensor was out of spec, so they replaced that sensor. This sensor was constantly complaining about "High Tire Pressure" and "Low Tire Pressure" so I'm glad they fixed it.

All in all, very happy with the service and hope we can get another 25,000 trouble-free miles before anything else needs to be replaced. (Besides the two things above, all the parts on the car are original!)