"Override" Test Function

Override displays are operated as defined under Selecting Test .

The ECM override feature allows testing of certain system functions regardless of normal program instructions. Upon selecting a test, the current operation of that function will be displayed as a percentage of its full range on the ECC panel. The display will alternate between "--" for 1 second followed by the normal program command for 10 seconds. This alternating display is a reminder that the function is not currently being overridden. Pressing the "WARMER" or "COOLER" buttons on the ECC panel initiates the override at which time the display will no longer alternate to "--" . Pressing the "WARMER" button increases the override value while pressing the "COOLER" button decreases the override value. Upon release of the button, the display may either remain at the overridden value or automatically return to normal program control. This depends on which function is being overridden at the time. If the display remains at the override value, normal program control can be resumed in one of three ways.

Selection of another override test will cancel the current override.
Selection of another system (i.e., ECM to BCM) will cancel the current override.
On some system overrides, overriding the value beyond either extreme (0 or 99) will display "--" momentarily and the jump to the opposite extreme. If the button is released while "--" is displayed, normal program control will resume and the display will again alternate.

The ECM override feature is unique in that any other test (Data, Input, etc.) may be active at the same time. After selecting an override, pressing the "OFF" button will allow selection of another test type and the ECC panel will continue to display the selected override. Pressing the WARMER or COOLER button during another test, it is possible to monitor the effect of the override on different vehicle parameters. An example of this is the ISC motor override. By selecting the ISC motor override and the displaying ECM data ED 11 RPM, it is possible to check minimum air RPM by pressing the COOLER button and allowing the ISC motor to fully retract while observing engine RPM. The following is a list of ECM Overrides.

ES00 - NONE

No override is active at this point.

ES01 - VCC

This override commands the VCC solenoid electrically on or off. The override is active at all times but hydraulic oil is present to the VCC only when the transmission is in second, third or fourth gear.
- WARMER
  
  By pressing and holding the warmer button, the VCC solenoid is commanded on. A "99" appears on the ECC panel.
- COOLER
  
  By pressing and holding the cooler button the VCC solenoid is commanded off. A "00" appears on the ECC panel.

ES02 - EGR FLOW

This system is not used in the 1989 PFI system. When this output is selected the CCP will display "----" which indicates that this system is not available for override.

ES03 - ISC MOTOR CONTROL

This override allows the ISC motor to be fully retracted to check minimum air RPM. This override will only be allowed with the throttle switch closed, transmission in park or neutral, and the car not moving. The override will automatically cease if any of these conditions are not met. Additionally this override will allow the full extension of the ISC motor when the engine is off, allowing the user to check full ISC authority. During the override the generator will be disabled and the A/C clutch will be commanded off to facilitate minimum air RPM checks.
- WARMER
  
  Pressing the warmer button returns the ISC motor to normal program control if the engine is running, and fully extends the ISC if the engine is not.
- COOLER
  
  Pressing and releasing the cooler button will cause the ISC motor to retract. The motor will slowly retract and come to rest at minimum air setting after approximately 20 seconds.

ES04 - INJECTOR CONTROL

The injector control override allows each individual injector to be turned off (0 pulse width) one at a time. This can be used in conjunction with parameter ED11 RPM as an engine cylinder power balance test. This override is only allowed with vehicle speed equal to 0 MPH and transmission in Park or Neutral. For best results the RPM should be elevated to the 1500 to 2000 RPM range and the throttle should be held steady.
- WARMER
  
  Pressing the warmer button selects injectors 1 through 8. The injector number corresponds to the cylinder number not the firing order. For example, injectors 1, 3, 5 and 7 are the front bank injectors from the front of the engine to the rear.
- COOLER
  
  Pressing and holding the cooler button electrically disables the selected injector. A "00" will appear on the ECC panel.

ES05 - FUEL PUMP RELAY

The fuel pump relay override will command the fuel pump relay to the turn off while the engine is running. This allows the oil pressure switch circuit to be checked (CKT 120). This override is allowed only with the engine running.
- WARMER
  
  Pressing the warmer button does not affect this override.
- COOLER
  
  Pressing and holding the cooler button disables the fuel pump relay. A "00" will appear on the ECC panel.

ES06 - AIR INJECTION REACTION

This system is not used in the 1989 PFI system. When this output is selected the CCP will display "---" which indicates that this system is not available for override.

ES07 - CRUISE FEEDBACK

The cruise feedback, or cruise control override, will command the servo out (0% stroke) or in (100% stroke) regardless of normal program control. This override is only allowed at key on, engine off. The cruise servo requires a vacuum supply for this override to operate. The servo will pull in once or twice after an engine run due to the vacuum reservoir but an external vacuum supply is needed for extended testing.
- WARMER
  
  Pressing the warmer button will slew the percent servo stroke up. Releasing the button will hold the servo at the displayed stroke until the override is exited.
- COOLER
  
  Pressing the cooler button will slew the percent servo stroke down. Releasing the button will hold the servo at the displayed stroke until the override is exited.