PCM Override
PURPOSE OF OVERRIDEThe Powertrain Control Module (PCM) override feature allows testing of certain system functions regardless of normal program instructions.
CURRENT FUNCTION DISPLAY
Upon selecting a test, the current operation of that function will be displayed on the Driver Information Center (DIC). If test conditions are not met, the Climate Control Panel (CCP) will display "==" in the place of override value selected. The display will alternate between "--" for 1 second followed by the normal program command for 5 seconds. This alternating display is a reminder that the function is not currently being overridden.
INITIATING AND CHANGING OVERRIDE
Pressing the WARMER or COOLER buttons on the CCP initiates the override at which time the display will no longer alternate to "--." Generally speaking, pressing the WARMER button increases the override value while pressing the COOLER button decreases the override value (exceptions are noted in the description of the override). 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:
1. Selection of another override test will cancel the current override.
2. Selection of another system (such as, Instrument Panel Cluster (IPC)) will cancel the current override.
3. On some system overrides, overriding the value beyond either extreme (0 or 99) will display "--" momentarily and jump to the opposite extreme. If the button is released while "--" is displayed, normal program control will resume and the display will again alternate.
PCM OVERRIDES
The available PCM Overrides are as follows:
PS00 NONE
No Outputs. No PCM Outputs can be overridden when PS00 is selected.
PS01 TCC Solenoid
PS01 may be used to override the commanded state of the TCC solenoid. When PS01 is selected, the current state of the TCC solenoid will be displayed for five seconds followed by "--" for one second to indicate normal PCM control of the TCC solenoid. During both normal PCM control and override control, a display of "00" means the TCC solenoid is de-energized and a display of "99" means it is energized. The TCC solenoid may be overridden "OFF" by pressing and holding the COOLER button or overridden "ON" by pressing and holding the WARMER button. In either case, releasing the button will return the TCC solenoid to normal PCM control. Keep in mind that the TCC is only able to be engaged when the transaxle is in 3rd or 4th gear.
PS02 EGR Solenoid
PS02 may be used to override normal EGR solenoid control. When PS02 is first selected, the display will alternate between "--" for one second and current commanded EGR status. Pressing the WARMER button will de-energize the EGR solenoid and the display will be 99 and vacuum will be applied to the EGR value. Pressing the COOLER button will energize the EGR solenoid, the display will be 00 and no vacuum will be applied to the EGR value.
PSO3 ISC Motor
The ISC motor may be overridden under certain conditions using PS03. When PS03 is first selected, the display will alternate between "--" for one second and "50" for three seconds to indicate normal PCM control of the ISC motor. This will continue until an ISC extend or retract override is attempted. If at any point an override is attempted without meeting the conditions stated below, "==" will be displayed.
ISC Extend:
The ISC motor may be extended using the WARMER button only under the following conditions:
^ Engine not running.
^ Vehicle speed is 0.
^ Transaxle is in Park or Neutral.
^ Throttle Position Switch is closed or throttle angle (PD01) is less than 4 degrees.
When these conditions are met and the WARMER button is pressed, the ISC motor will extend as far as it can and "99" will be displayed.
ISC Retract:
The ISC motor may be retracted using the COOLER button only under the following conditions:
^ Vehicle speed is 0.
^ Transaxle is in Park or Neutral.
When these conditions are met and the COOLER button is pressed, the ISC motor will retract until the throttle switch opens and "00" will be displayed. While in the ISC retract override, the EGR solenoid and the A/C compressor clutch will be commanded off.
PS04 Fuel Injector Disable
PS04 may be used to individually disable injectors to note the effect on engine performance. The following conditions must be met to allow injector override:
^ Vehicle speed is 0.
^ Transaxle in Park or Neutral.
If the above conditions are not met, fuel injector override will be suspended until these conditions are met at which time the override will resume with injector # 1. When PS04 is first selected, the display will alternate between "--" for one second and "01" for five seconds ("01" signifying injector # 1). Once PS04 is selected, the WARMER button is used to select the injector to be tested and the COOLER button is used to disable the selected injector. Pressing the WARMER button will increment the display and the injector number selected for testing from # 1 through # 8 and back to # 1 again (injector number corresponds to cylinder number). Pressing the COOLER button disables the selected injector only while the button is held. While the injector is disabled, "00" will be displayed. While PS04 override is selected, the A/C clutch will be disabled. Additionally, while an injector is being disabled, ISC motor position and fuel integrators are frozen.
PS05 Fuel Pump Relay
PS05 may be used to de-energize the fuel pump relay. The following conditions must be met to override the fuel pump relay:
^ Vehicle speed is 0.
^ Transaxle in park or neutral.
When PSO5 is first selected, the display will alternate between "--," for one second and the current state of the fuel pump relay output for five seconds ("00" means fuel pump relay off and "99" means fuel pump relay "ON"). Pressing the COOLER button will turn the relay "OFF" and display "00." Pressing the WARMER button will have no effect on the relay. The override will only be active while the COOLER button is pressed. Normal control will resume when the button is released.
PS06 Not Used
No PCM outputs can be overridden when PS06 is selected.
PS07 C/C Servo Position
PS07 may be used to override commanded servo position through the use of the cruise control vent and vacuum solenoids. Servo override is not allowed with the engine running. The Cruise "ON/OFF" switch must be "ON" to operate the Cruise Control Servo. When PS07 is first selected, the commanded servo position will be set to 0 and the display will alternate between "--" for one second and "O0" for five seconds. Pressing the WARMER button will cause the commanded servo position to increment. Pressing the COOLER button will cause the commanded servo position to decrement. Using the WARMER and COOLER buttons, the commanded servo position may be overridden from 0 to 99. The engine must be run prior to entering this override (to build up a vacuum reserve) if cruise servo movement is desired.
PS08 Cooling Fan Relays
PS08 may be used to override the cooling fan relays. When PS08 is selected, the current state of the high and low speed fan relay outputs will be displayed as two digits. The left digit represents the low speed fan relay state ("1" means energized, "0" means de-energized) and the right digit represents the high speed fan relay state. Pressing the WARMER button changes the high speed fan relay state to "1" if it was "0" or to "0" if it was "1." Pressing the COOLER button changes the low speed fan relay state to "1" if it was "0" or to "0" if it was "1." The table below shows the four possible states of the cooling fan relays and their corresponding cooling fan operation.
OUTPUT STATE COOLING FAN OPERATION
00 FANS OFF
01 NOT A VALID TEST
10 BOTH FANS ON LOW
11 BOTH FANS ON HIGH
PS09 Temporary Spark Advance
PSO9 may be used to temporarily override the spark advance used by the ignition system. When PS09 is selected, the current spark advance will be displayed. While the spark advance is being overridden, the PCM will continue to compute the normal spark advance based on engine data. This value will be used as a maximum spark advance override. If at any time, the override spark advance exceeds normal spark advance, the normal spark advance will be used and "==" will be displayed. To initiate spark override, the COOLER button must be pressed. Prior to this, the WARMER button will do nothing. When the COOLER button is first pressed, the spark advance will be set to 10 degrees. Afterwards, the WARMER button will increment spark advance up to the maximum advance calculated by the PCM and the COOLER button will decrement spark advance down to a minimum of 0. The current spark advance will be displayed for the duration of the override.
PS10 Injector Flow
PS10 may be used to fire each injector for a specific period of time thereby comparing injector flow. The following conditions must be met to override the injectors:
^ Vehicle speed is 0.
^ Transaxle in park or neutral.
^ Engine speed is 0.
If the above conditions are not met, fuel injector override will be suspended until these conditions are met at which time the override will resume with injector # 8. When PS10 is first selected, the display will alternate between "--" for one second and "08" for five seconds ("08" signifying injector # 8). Once PS10 is selected, the COOLER button is used to select the injector to be tested and the WARMER button is used to fire the selected injector. Pressing the COOLER button will decrement the display and the injector number selected for testing from # 8 through # 1 and back to # 8 again (injector number corresponds to cylinder number). Pressing the WARMER button fires the selected injector. While the injector is fired, "99" will be displayed. PS10 will only allow each injector to be fired once between engine runs to avoid flooding.
PS11 Transaxle Shift
PS11 may be used to override shift "A" and shift "B" solenoid outputs and thus control shifts while in drive. The following conditions must be met to override shifts:
^ Gear selector in D4.
^ Vehicle speed less than 65 mph.
If these conditions are not met, transaxle shift override will not be allowed and "==" will be displayed. When PS11 is selected and the above conditions are met, the current commanded gear will be displayed. Pressing the WARMER button will cause the transaxle to upshift and display the new commanded gear. Pressing the COOLER button will cause the transaxle to downshift and display the new commanded gear. A 3-2 downshift is not allowed above 60 mph. A 2-1 downshift is not allowed above 30 mph. If either is commanded while in overrides, the downshift will not occur and "==" will be displayed while the COOLER button is pressed. While in transaxle shift override, the torque converter clutch will be disabled.