2004 Mercury MontereyFACTORY OEM SERVICE PROCEDURE

Unlimited Key Mode Programming

Enabling Unlimited Key Mode 

NOTE: Unlimited Key Mode is intended for use by those fleet customers who need more than 8 keys for their vehicle.
  1. The customer must choose a 8-digit, non-00,00,00,00 number that will be programmed to all of their vehicles. All customer vehicles need to use the same number. Valid digits are 0-9 plus the letters A-F.
    2. NOTE: If the powertrain control module (PCM) PID: UNLIMITED TRANSPONDER KEY ID is not displayed on screen, Unlimited Key Mode is turned on, and must be turned off before viewing the stored code.
  2. To view/change the stored code, follow the procedure for turning off Unlimited Key Mode below. Check the PID: UNLIMITED TRANSPONDER KEY ID and compare its value against the code chosen in Step 1.
  3. Using the diagnostic tool, select PCM from the menu. Follow SECURITY ACCESS to obtain security access. For additional information, refer to ANTI-THEFT SECURITY ACCESS .
  4. Turn OFF the unlimited key mode to view the security key pid.
  5. If the Unlimited Transponder Security Key PID was 00,00,00,00, select Active Command: SET UNLIMITED TRANSPONDER KEY. Enter the 4-digit code chosen by the user.
  6. Select: ENABLE UNLIMITED KEY MODE/RESET SERVICE BIT, if applicable.
  7. Select: IGNITION CODE ERASE.
  8. Disconnect the diagnostic tool and turn the ignition keys off.
  9. Program in 2 ignition keys to enable the vehicle by cycling keys from OFF to RUN.
  10. Program any additional keys using either Key Programming Using Two Programmed Keys or KEY PROGRAMMING USING DIAGNOSTIC EQUIPMENT .

Disabling Unlimited Key Mode 

  1. Using a diagnostic tool, select PCM from the menu. Follow SECURITY ACCESS to obtain security access. For additional information, refer to ANTI-THEFT SECURITY ACCESS .
  2. Select: DISABLE UNLIMITED KEY MODE.
  3. Select: IGNITION KEY CODE ERASE and RESET SERVICE BIT, if applicable.
  4. Disconnect the diagnostic tool and turn the ignition key to OFF.
  5. Program in 2 keys to enable the vehicle.
  6. Program any additional keys using either Key Programming Using Two Programmed Keys or KEY PROGRAMMING USING DIAGNOSTIC EQUIPMENT .
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.