2005 Rendezvous EVAP System Test: Troubleshooting Scan Tool Inability to Initiate

Experiencing trouble initiating an EVAP (Evaporative Emission) system test using your scan tool on a 2005 Pontiac Rendezvous, or similar GM vehicle? You’re not alone. The General Motors EVAP monitor procedure is notoriously complex across their vehicle lineup, and getting the system to run its self-test can be frustrating. This guide, based on official GM procedures, will walk you through the steps to ensure your 2005 Rendezvous meets all the criteria for initiating the EVAP system monitor and achieving an “EVAP System Ready” status. This is crucial for passing emissions tests and diagnosing potential EVAP system leaks.

Understanding the GM EVAP Monitor Procedure

The EVAP system monitor is designed to detect leaks in your vehicle’s evaporative emissions control system. This system prevents harmful fuel vapors from escaping into the atmosphere. For the monitor to run, a series of very specific conditions must be met. These conditions, often referred to as “enable criteria,” are in place to ensure the test is performed accurately and reliably. If even one of these conditions isn’t met, your scan tool may not be able to initiate the EVAP test, and the monitor status will remain “Not Ready.”

This procedure is relevant for all GM vehicles, including the 2005 Pontiac Rendezvous, regardless of aftermarket modifications like performance tunes or AFM (Active Fuel Management) disablers. It’s not uncommon for it to take multiple drive cycles, potentially spanning several days and even a full tank of gas, to satisfy all the necessary parameters for the EVAP monitor to transition from “NOT READY” to “READY.”

Inspection/Maintenance (I/M) Complete System Set Procedure

The following procedure outlines the GM Inspection/Maintenance (I/M) Complete System Set Procedure. This process aims to fulfill all the prerequisite conditions for executing the I/M readiness diagnostics and completing the drive cycles for those specific diagnostics. Successful completion of this procedure should set all I/M monitored diagnostic tests to “YES.”

If any of your I/M System Status indicators are showing “NO” when checked with a scan tool, performing this procedure is recommended.

Checking I/M Readiness Status

Before starting, use your scan tool to check the I/M Data List. This will show the current status of your vehicle’s monitors and whether the I/M readiness diagnostic tests can be initiated. Focus particularly on the EVAP System Status indicator.

Conditions for a Successful Cold Start

A “cold start” is essential for initiating the EVAP monitor. Ensure the following conditions are met before starting the procedure:

• Voltage: Battery voltage between 11-18 volts.
• Barometric Pressure (BARO): Greater than 75 kPa.
• Engine Coolant Temperature (ECT): Between 4-30°C (39-86°F) at startup.
• Intake Air Temperature (IAT): Between 4-30°C (39-86°F) at startup.
• IAT and ECT Difference: Difference between IAT and ECT less than or equal to 6°C (10.8°F).
• Ambient Air Temperature: Between 4-30°C (39-86°F).
• Fuel Level: Between 15-85 percent of fuel tank capacity.
• Fuel Alcohol Content:
  • Without RPO LMG (engine code): Less than 15 percent ethanol.
  • With RPO LMG (engine code): Less than 87 percent ethanol. (Check your vehicle’s RPO code sticker, usually located in the glove box or door jamb, to determine if your Rendezvous has the LMG engine option).

Verifying System Readiness

After ensuring these conditions are met, use your scan tool to review the Inspection/Maintenance (I/M) System Status indicators again. Ideally, all indicators should report “YES” before proceeding.

Step-by-Step I/M System Set Procedure

Important Preparation: Before starting the engine, and after verifying all “cold start” conditions are met, turn the ignition key to the “OFF” position for approximately 5 minutes. This cool-down period allows the heated oxygen sensors (HO2S) to cool down, which is crucial for the procedure. Once the engine is started in the following steps, do NOT turn it off until the procedure is complete.

1. Cold Start Conditions: Double-check that your 2005 Rendezvous still meets all the “Conditions for a Cold Start” listed above.

   • EVAP System Status “NO”: If the EVAP I/M System Status indicator is “NO” at the beginning of this process, and you have access to an EVAP Service Bay Test with your scan tool, perform that test first.
   • No EVAP Service Bay Test: If the Service Bay Test is unavailable, understand that it may take up to 6 drive cycles, with up to 17 hours between each drive cycle, for the EVAP I/M System Status to change to “YES” using this procedure alone. Patience is key.
   • O2S Heater System Status “NO”: If the O2S Heater System Status indicator is “NO,” ensure the ignition has been off for at least 10 hours before starting this procedure.

2. Parking Brake & Transmission: Engage the parking brake fully. Place the transmission in “Park” for automatic transmissions, or “Neutral” for manual transmissions.

3. Turn Off Accessories: Switch off all vehicle accessories, including the HVAC system (air conditioning and heating), headlights, radio, and any aftermarket or add-on electrical equipment.

4. Idle to Temperature: Start the engine and let it idle for at least 2 minutes, until the engine coolant temperature reaches 65°C (149°F). Monitor engine temperature using your scan tool if necessary.

5. Elevated Idle – Part 1: Run the engine for 6.5 minutes under these conditions:

   • MAF (Mass Air Flow) parameter reading between 4-30 g/s.
   • Engine speed held steady between 1000-3000 RPM. Maintain a consistent RPM within this range; avoid fluctuations.

6. Idle – Part 2: Return the engine to a normal idle speed for 1 minute. Do not touch the accelerator pedal during this idle period.

7. Drive Simulation: Apply and hold the brake pedal firmly. Shift the transmission to “Drive” (automatic) or depress the clutch pedal (manual). Operate the vehicle (while stationary, in gear, with brakes applied) under these conditions for 2 minutes:

   • Depress the accelerator pedal slightly until the TP (Throttle Position) Sensor angle is more than 2 percent.
   • MAF signal reading between 15-30 g/s.
   • Engine RPM held steady between 1200-2000 RPM.

   Crucial Note: Do NOT touch the accelerator pedal during the idle period immediately preceding this step. Any change in the TP Sensor angle or an increase in engine speed before you are instructed to apply the accelerator will invalidate this portion of the test, and you may need to restart the entire procedure.

8. Idle – Part 3: Release the accelerator pedal. Shift the vehicle back to “Park” (automatic) or “Neutral” (manual) and release the clutch pedal. Allow the engine to idle for 2 minutes.

9. Throttle Bursts: Quickly depress the accelerator pedal until the TP Sensor Angle is more than 8 percent, then immediately release it back to idle. Repeat this process a total of 3 times.

10. Idle – Part 4: Allow the engine to idle for at least 2 minutes.

11. Low Speed Drive: Release the parking brake and carefully drive the vehicle at a speed of 24 km/h (15 mph) or slower for 2 minutes. Maintain a slow, steady speed.

12. Highway Speed Drive: Continue driving the vehicle for at least 5.5 miles (8.8 kilometers) at a speed between 45-112 km/h (28-70 mph). During this segment, ensure the vehicle reaches a speed of at least 80 km/h (50 mph) at some point.

13. Deceleration Fuel Cut-Off: Release the accelerator pedal completely for at least 2 seconds. This allows the vehicle to enter “decel fuel cut-off,” a condition necessary for the EVAP monitor to run.

14. Moderate Acceleration: Depress the accelerator pedal again until the TP Sensor angle increases by 3-20 percent. Maintain a safe and steady speed under this moderate acceleration for 1 minute.

15. Stop and Idle – Part 1: Safely bring the vehicle to a complete stop. Keep the transmission in “Drive” (automatic) or “Neutral” with the clutch pedal depressed (manual) and engage the parking brake. Allow the engine to idle for 2 minutes.

16. Park and Idle – Part 2: Shift the transmission to “Park” (automatic) and apply the parking brake, or “Neutral” (manual) and release the clutch pedal.

    Critical Wait Period: Do NOT disturb the vehicle or turn the ignition “ON” until instructed. Any disturbance to the vehicle during the next step may invalidate the final portion of the test.

17. Ignition OFF – Cool Down: Turn the ignition key to the “OFF” position and exit the vehicle. Do NOT disturb the vehicle in any way for 45 minutes. This extended cool-down period is essential for the EVAP system monitor to complete its test.

18. Final System Status Check: After the 45-minute wait, observe the Inspection/Maintenance (I/M) System Status again using your scan tool. Ideally, all I/M System Status indicators should now display “YES,” including the EVAP System Status.

    • EVAP System Status Still “NO”: If the EVAP I/M System Status indicator remains “NO” after this procedure, turn the ignition off for a full 17 hours. After the 17-hour cool-down, ensure the vehicle again meets all the “Conditions for a Cold Start.” Then, repeat steps 12-18 up to six more times, or until the EVAP I/M System Status indicator finally transitions to “YES.” If it persistently remains “NO” after multiple attempts, consult the Inspection/Maintenance (I/M) System DTC Table (Diagnostic Trouble Code Table) specific to your 2005 Pontiac Rendezvous to identify any Diagnostic Trouble Codes (DTCs) that did not run. Follow the “Conditions for Running the DTC” information associated with those codes to further troubleshoot the EVAP system.

    • Other I/M Status Indicators “NO”: If any other I/M System Status indicators besides EVAP are still “NO,” refer to the Inspection/Maintenance (I/M) System DTC Table for the indicator in question. This table will link the “NO” indicator to specific DTCs. Again, follow the “Conditions for Running the DTC” for those codes to address the underlying issues preventing those monitors from setting.

By meticulously following this GM Inspection/Maintenance (I/M) Complete System Set Procedure, you should significantly increase your chances of successfully initiating the EVAP system monitor on your 2005 Pontiac Rendezvous and achieving an “EVAP System Ready” status. Remember, patience and attention to detail are key when dealing with the intricacies of GM’s EVAP monitoring system.