Did you know your 2004-2006 Pontiac GTO has a “Secret Menu”? It’s actually not a secret menu but it is a “Diagnostic Test” for your vehicle. This menu will diagnose your vehicle and tell you such things as coolant temperature, battery voltage, remaining fuel, and more.
This menu can be accessed by doing the following steps:
- On the dashboard to the right of the steering wheel you will see the trip computer buttons, which also act as the menu buttons:
- While holding both the “MODE” and “SET” buttons down at the same time, turn the ignition key to the “accessory on” position. You do not need to start the car at this point. Just turn the key enough to see the dashboard cluster activate. If done correctly you should see the screen on your dash cluster say “Ver:” along with a “Serial No.” reading similar to the screenshot below. Once you see this you can release the buttons.
- From here you can decide to either leave the key in the accessory on position, or start the car. I recommend starting the car to get the full diagnostic scan of your vehicle. Do not turn the key to the off position or the diagnostic test menu will be turned off.
- Press the “MODE” button to scroll through the diagnostics of the vehicle. You will see the following items:
1. GM PART NUMBER – Part number of the instrument gauge cluster
2. SWITCH VOLTAGE – Volts going to the Mode Switch
3. BATTERY VOLTAGE – Volts of your car battery
4. BRAKE VOLTAGE – At “0” until you press the brakes
5. FUEL CAL PART # – Fuel Calibration possibly?
6. PETROL SENDER VALVE – Tells the fuel gauge how much fuel you have. 255/255 being a full tank.
7. REMAINING FUEL – How much fuel is left in the gas tank
8. INSTANTANEOUS FUEL – How much fuel is being used with the vehicle running
9. COOLANT TEMP – Temperature of the coolant
10. SPEED – Pretty self explanatory. Your vehicle speed.
11. TACHO – Tachometer reading in Revolutions Per Minute (RPM’S)
12. PARK LAMPS – On or Off value
13. DAYTIME RUNNING LAMPS – ON or Off value
14. TROUBLE CODES – I assume zero’s are good. Have not used this for trouble codes.
15. MYSTERY – Prepare to have your dashboard gauges go crazy. It’s actually a dash gauge cluster test. It’s normal, you didn’t break anything, but you freaked out when it happened didn’t you!
- When you want to exit the diagnostic menu simply turn off the car and remove the key. The dash cluster will go back to normal.