Secrets of the C5

The little yellow "helper light" on the bottom of the rear-view mirror that illuminates the shifter area

Put your key in the driver's door and turn it twice towards the front to unlock the passenger door and a third time to pop the trunk.

Pop the trunk and also pop the gas cap cover by pulling on metal lines hidden in the back.

The little slotted cover on the dash behind the steering wheel is where the inside air temperature sensor is located.

All of the option codes are in the glove box.

Tire inflation recommended pressures are on the driver's door

The thing that looks like a little LED near the DIC buttons is a light sensor

The thing that looks like a little LED near the defroster vent is a UV sensor for determining A/C usage to compensate for the heating effect of the sun

The build sheet is in the front re-bar

If you leave your turn signal on, in about 1 minute it will start to ding (loud enough to hear over the stereo) to let you know you have old timers disease.

You can reset the oil life by pumping the gas pedal 3 times (but not with the engine running)

Hold down the reset button while on one of the trip odometers and it changes that reading to the miles you've traveled since last starting the engine.

Hold down the Active Handling button for 5 sec. to engage "Competitive Driving" on cars equipped with active handling (2000 and previous years must be stopped.)

If you pull the seatbelts all the way out while you're buckled in, they ratchet back in to hold you tighter into the seat.

Simply remove fuse #2 under the hood and your DRLs will be out permanently. Only thing affected is that when you unlock at night using the key fob your front turn signal lights and back up lights will not will not flash. Your front turn signals will operate normally, however.

The side-view mirrors can twist both forward and backward, decreasing the chance of damage if struck.

There is a release opening with a flap to let air out of the car when the hatch is closed. It is located just above the driver side rear compartment, behind the carpet and on the side of the car. Not that it really works well.

Also you can ground your amp to a screw/bolt that holds the rear middle compartment to the frame.

If you have a 6-speed car you can pop the trunk when the car is running by lifting the e-brake.

There is a spot on the driver side just out of the middle compartment under the carpet for the lug nut key. You should have a compartment on the drivers & passenger's side (in the trunk) and a center compartment. On the left (drivers) side of the center compartment, on the left side where the center cover fits, there is an 'indent' that holds the wheel lock key.

If you turn on the headlights, then go to parking light position, the lamps remain up but the headlights are not left on.

HUD has a shift light for manuals.

You can easily shift the M6 trans up or down without the clutch if you match revs. (Not great for longevity, however.)

You can eject the CD from the in-dash player without turning on any power. Don't even need key in the ignition.

The cruise will disengage if you purposely make sharp side to side turns while cruising at say 60-80 mph.

When the engine is shut off, you can get the odometer reading by turning on the parking lights.

You can program setting #3 (both memory buttons at once) in the seat memory to run the seat back and steering wheel forward for getting in/out of the car with the engine running.

If you hate DRLs you can pull the e-brake ONE click and they go off


The option codes are on the bottom of the driver's side rear compartment cover.


The coolant temp gauge is not symmetrical. The hash marks on the left half of the gauge (100-220 degrees) are 15 degrees each and on the right half (220-260 degrees) the hash marks are 5 degrees each

M6 Trans tips:

First things first, details as to what the failures are is critical to the EXACT cause of the problem.
SHIFTER ADJUSTMENT, this is the first step in ALL problems with shifting. It is CRITICAL that this be done first, before proceeding with any and all concerns.
Carbon composition friction surfaces are critical for shifting for notchy shifting. These friction surfaces last forever, BUT, they require substantial break in, and this can be helped. Adding Redline D4 ATF will substantially help cold shifting concerns. This is due to the substantial friction modifier package that is NOT in regular Dexron 3 automatic transmission.
After that, the bending of shift forks, in all cases, is due to speed shifting, power shifting or the like, where the syncronizers do NOT have time to line up. This, in turn, creates a jambing of the syncronizer hub to the engagement teeth of the blocker ring. This creates stress on the shifter fork, so instead of breaking, it bends.
3/4 shifting fork is the one that has been updated to steel, for this exact condition.
My recommendation to my new c5 customers was this.
'If you plan on racing, first, install Redline D4 ATF, as this will make the syncronizers line up much faster and lessen the chance that you will damage a syncronizer, hub, teeth or bend a fork.'

Then, I would recheck my shifter adjustment and send them on their way.
I have had numerous drag cars running high 11s, with only 1 failure, which was a broken main shaft on drag radials. Over 80k on the car, the syncronizers showed slight tooth wear, but NO frictional surface wear and engagement was still very smooth and acceptable.
So, with that in mind, I love the T56 and when understood what type of stresses the transmission endures and be PROACTIVE with maintenance, it will last well.