Hummer H2. Manual - part 43

Monitor Run Process Tip 

The following is an outline of the Monitoring Run Process, including suggestions and tips in order to aid in the 
process of meeting the enabling criteria for these monitors. The most efficient order has been outlined below. 
For example, the first two monitors have very similar enable criteria; it is possible that the Evaporative Leak 
Detection Monitor will run during the O2 Sensor Heater Monitor.  

Evaporative Leak Detection Monitor (If Equipped With An LDP System) 

This monitor requires a cold start, usually an overnight soak or parked for at least 8 hours without the engine 
running. The engine coolant temperature must be within 10 degrees of ambient/battery temperature, and the 
sensed Ambient (outside) Temperature must be between approximately 40°F and 90°F.  

O2 Sensor Heater Monitor 

This monitor requires a cold start, usually an overnight soak or parked for at least 8 hours without the engine 
running. The engine coolant temperature must be within 10 degrees of ambient/battery temperature, and the 
sensed Ambient (outside temperature) must be between approximately 0°F and 100°F. The monitor should run 
directly after starting the engine.  

Catalyst Monitor 

The vehicle will need to be driven at a steady highway speed for a few minutes. The monitor will typically 
enable and start running at approximately 35 to 40 MPH for 2.5L and 4.0L engines, 50 to 60 MPH for all 
others). If the vehicle is equipped with a manual transmission, using 4th gear may assist in meeting the monitor 
running criteria.  

O2 Sensor Monitor 

The vehicle will need to be driven for a period of time at a steady highway speed. Approximately 35 to 40 MPH 
for 2.5L and 4.0L engines, 50 to 60 MPH for all others and brought to a stop for a short period of time with the 
A/T left in Drive. The O2 Monitor will not run in Park or Neutral, except for vehicles equipped with a M/T.  

Purge Monitor 

The Purge Free cells must be updated before the monitor will run. The enabling conditions are similar to the O2 
Sensor Monitor enabling conditions such as, the vehicle will need to be driven for a period of time at highway 
speeds and brought to a complete stop. The Purge Flow Monitor will attempt to run every OTHER throttle 
closure. If all of the parameters are met and it still does not run, with your foot firmly on the Brake, quickly 
open and close the throttle, this will allow another Purge Free update, and then the Purge Flow Monitor should 
run.  

Misfire Monitor 

Misfire monitor is continuously running during engine operation. For the Misfire monitor to be enabled, the 

CARB Readiness and all additional OBD information will be cleared. 

 

1998 Chevrolet Pickup C1500 

DRIVE CYCLES OBD-II Vehicles - OBD-II Readiness Monitors

  

Adaptive Numerator must be learned since battery disconnect and every Key on there after (known as Power-on 
learning).  

The Adaptive Numerator is a software learning routine that tells the PCM where the crankshaft slots are. Since 
every crankshaft is different, the PCM must learn exactly where its particular crankshaft slots are; otherwise its 
RPM calculations would be wrong. After a battery disconnect and then a power-up of the PCM, the Adaptive 
Numerator is set to a value which it would be at if everything were perfect (crankshaft slots, sensors, PCM 
hardware, etc.). If the Adaptive Numerator is equal to the default value, no learning has happened and the 
Misfire Monitor will not run.  

To allow the PCM to learn the Adaptive Numerator, the following must happen:  

z

Open Throttle.  

z

Engine Cool Temp Above 100°F Or If Below 100°F, Wait For ECT Rise Of 59°F.  

z

More than 10" Vacuum.  

z

Above 1200 RPM.  

z

Below 3000 RPM - A/T.  

z

Below 3488 RPM - M/T.  

Once the PCM has learned the Adaptive Numerator, the Misfire Monitor will run. 

Fuel System Monitor 

Fuel System monitor is continuously running during engine operation.  

1995-2002 SBEC 

OBD-II Monitor Enabling Criteria FWD/AWD SBEC PCM Equipped Vehicles 

The following procedure has been established to assist technicians in the field with enabling and running OBD-
II Monitors on FWD cars and FWD/AWD vans equipped with Single Board Engine Controller (SBEC). The 
order listed in the following procedure is intended to allow the technician to effectively complete each monitor 
and to set the CARB Readiness Status in the least time possible.  

Monitor Run Process Tip 

The following is an outline of the Monitoring Run Process, including suggestions and tips in order to aid in the 
process of meeting the enabling criteria for these monitors. The most efficient order has been outlined below, 

NOTE:

Once the monitor run process has begun, DO NOT turn off the ignition. By 
turning the ignition key off, the monitor enabling conditions will be lost. Only 
the O2 Heater Monitor runs after key off. 

NOTE:

By performing a battery disconnect, or erasing diagnostic trouble codes, the 
CARB Readiness and all additional OBD information will be cleared. 

 

1998 Chevrolet Pickup C1500 

DRIVE CYCLES OBD-II Vehicles - OBD-II Readiness Monitors

  

the first two monitors have very similar enable criteria, so it is possible that the Evaporative Leak Detection 
Monitor will run while operating the vehicle to enable the Catalyst Monitor.  

Evaporative Leak Detection Monitor (If Equipped) 

This monitor requires a cold start, usually an overnight soak or parked for at least 8 hours without the engine 
running. The engine coolant temperature must be within 10 degrees of ambient/battery temperature, and the 
sensed Ambient (outside) temperature must be between approximately 40°F and 90°F.  

Catalyst Monitor 

The vehicle will need to be driven at a steady highway speed for a few minutes. The monitor will typically 
enable and start running around 45 to 60 mph under normal driving conditions. If the vehicle is equipped with a 
manual transmission, using 4th gear may assist in meeting the monitor running criteria.  

EGR Monitor 

The EGR monitor enable conditions are basically that the vehicle is in closed loop operation and coolant 
temperature above 170°F. It is necessary to maintain the TPS, MAP, MPH and RPM ranges at a constant with 
very little fluctuation to allow the monitor to complete during the cycle.  

O2 Sensor Monitor 

The vehicle will need to be driven for a period of time at highway speeds and brought to a complete stop for a 
short period of time, with the A/T left in Drive the monitor should run. The O2 Monitor will not run in Park or 
Neutral on A/T equipped vehicles.  

Purge Monitor 

The Purge Free cells must be updated before the monitor will run. The enabling conditions are similar to the O2 
Sensor Monitor enabling conditions such as, the vehicle will need to be driven for a period of time at highway 
speeds and brought to a complete stop. The Purge Flow Monitor will attempt to run every OTHER throttle 
closure. If all of the parameters are met and it still does not run, with your foot firmly on the Brake, quickly 
open and close the throttle, this will allow another Purge Free update, and then the Purge Flow Monitor should 
run.  

O2 Sensor Heater Monitor 

The vehicle will need to be driven for a period of time at highway speeds to satisfy the enabling conditions for 
the O2 Sensor Heater Monitor. The monitor runs with the ignition key off after vehicle operation. Allow the 
vehicle to hot soak for a few minutes before checking to determine if the monitor completed the cycle. Turning 
the key on prematurely will abort the monitor test and the vehicle will have to be driven to arm the enabling 
conditions again.  

Misfire Monitor 

Misfire monitor is continuously running during engine operation. For the Misfire monitor to be enabled, the 
Adaptive Numerator must be learned since battery disconnect and every Key on there after (known as Power-on 

 

1998 Chevrolet Pickup C1500 

DRIVE CYCLES OBD-II Vehicles - OBD-II Readiness Monitors

  

learning).  

The Adaptive Numerator is a software learning routine that tells the PCM where the crankshaft slots are. Since 
every crankshaft is different, the PCM must learn exactly where its particular crankshaft slots are; otherwise its 
RPM calculations would be wrong. After a battery disconnect and then a power-up of the PCM, the Adaptive 
Numerator is set to a value which it would be at if everything were perfect (crankshaft slots, sensors, PCM 
hardware, etc.). If the Adaptive Numerator is equal to the default value, no learning has happened and the 
Misfire Monitor will not run.  

To allow the PCM to learn the Adaptive Numerator, the following must happen:  

z

Open Throttle.  

z

Engine Cool Temp Above 100°F, Or If Below 100°F Wait for ECT Rise of 59°F.  

z

More Than 10" Vacuum.  

z

Above 1200 RPM.  

z

Below 3000 RPM - A/T.  

z

Below 3488 RPM - M/T.  

Once the PCM has learned the Adaptive Numerator, the Misfire Monitor will run.  

Fuel System Monitor 

Fuel System monitor is continuously running during engine operation.  

FORD MOTOR CO. 

1996-99 GASOLINE MODELS 

Introduction 

The purpose of the OBD-II drive cycle is to execute the OBD-II monitors and identify any concerns with the 
OBD-II system. The DTC P1000 code will be erased of all OBD-II monitors have completed during the OBD-II 
drive cycle.  

The scan tool will be used to observe the status of each OBD-II monitor at the completion of the OBD-II drive 
cycle. The completion status of the Exhaust Gas Recirculation (EGR), Heated Oxygen Sensor (HO2S), 
Evaporative emission (EVAP), secondary Air Injection (AIR) (if applicable) and catalyst efficiency monitors 
can be monitored during the OBD-II drive cycle by viewing the On-Board Readiness Menu on the scan tool.  

Vehicle Preparation for OBD-II or Monitor Repair Verification Drive Cycle 

WARNING:

Strict observance of posted speed limits and attention to driving 
conditions are mandatory when proceeding through the following drive 
cycles. 

 

1998 Chevrolet Pickup C1500 

DRIVE CYCLES OBD-II Vehicles - OBD-II Readiness Monitors