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Home >> Cadillac >> 1989 >> Fleetwood FWD V8-273 4.5L >> Repair and Diagnosis >> Powertrain Management >> Computers and Control Systems >> Testing and Inspection >> Initial Inspection and Diagnostic Overview >> - Description of On-Board Diagnostics >> Diagnostic Displays >> PCM/ECM Display >> Overides

Overides


DESCRIPTION:

This mode can be initiated after E.9.5 and is displayed on the Fuel Data Center. Depressing the "ECON" button at this time will bring the display to E.6.1 and initiate this test. To advance the display, depress the "HI" button on the CCP. If the test conditions are not appropriate performing the test, CCP will show "--" until test conditions are correct or test is bypassed. To return to .1 lower number parameter or to jump directly to E.6.4, depress the "LO" button on the CCP. The test selections available are the following:

a. E.6.1 - Viscous Converter Clutch (VCC) override.
b. E.6.2 - Exhaust Gas Recirculation Valve (EGR) override.
c. E.6.3 - Idle Speed Control (ISC) override.
d. E.6.4 - Cruise Control override.

A brief summary of each test is described below:

E.6.1 While in this mode, the ECM will transmit the current commanded state of the VCC to the BCM for display. This is done at all times when the VCC solenoid override mode is active. If the "WARMER" button is depressed, the VCC solenoid is commanded "ON" for as long as the button is depressed. If the "COOLER" button is depressed, the VCC solenoid is commanded "OFF" for as long as the button is depressed. If no button is depressed, the ECM controls the VCC solenoid normally.

E.6.2 While in this mode, the ECM will transmit the current commanded state of the EGR flow, to the BCM, for display. The indication "99" reflects full EGR flow and "00" reflects no EGR flow. This is done at all times when the EGR solenoid override mode is active. If the "WARMER" button is depressed, the EGR is commanded "ON" for as long as the button is depressed. If the "COOLER" button is depressed, the EGR solenoid is commanded "OFF" for as long as the button is depressed. If no button is depressed, the ECM controls the EGR solenoid normally. NOTE: Due to the use of a positive backpressure type EGR valve, this test will have no significance at idle.

E.6.3 While in this mode, the ISC motor can be commanded and held to a fully retracted position through the use of the CCP "COOLER" and "WARMER" buttons. For this function to be enabled, the vehicle must be standing still and the transmission placed in park or neutral. If the "COOLER" button is depressed, the ISC retracts and is held to its low position. The ECM will transmit a "00" to the BCM for display on the CCP when this button has been depressed. Depressing the warmer button issues an "extend" command to the ISC motor until the throttle switch closes. The ECM will transmit a "99" to the BCM for display on the CCP when this button is depressed. When the throttle switch closes, normal control of the ISC is restored. During this test, the A/C compressor clutch is commanded "OFF", the EGR is commanded "OFF" and the spark advance is fixed.

E.6.4 While in this mode, the cruise control commanded percent servo stroke is able to be changed from 0 to 100% of its stroke. To perform this test. the engine cannot be running. The ECM must see the engine RPM as 0. Depressing the "WARMER" button will command an increase in servo position 1% at a time to a maximum of 100%. Depressing the "COOLER" button will decrease the servo commanded position to a minimum of 0. The ECM will transmit the current commanded state to the BCM for display on the CCP.

COOLING FANS

DESCRIPTION:

.7.0 must be displayed on the Fuel Data Center panel before the coolant fans override feature can be selected. This feature allows the service technician to manually override the BCM's automatic control of coolant fans speed. To manually command either fans on of fans off, proceed as follows:

1. Depress and release the "ECON" button on the ECC. The coolant fans override mode begins as the display switches from .7.0 to F.8.5. It is possible to leave the coolant fans override mode at any time and return to .7.0, by clearing ECM or BCM codes.

2. To command "fans on" hold in the "HI" button on the ECC. Fan speed should increase form low to medium to high in 14 seconds. Releasing the "HI" button will return the calculation of fan speed to automatic BCM control.

3. To command "fans off" hold the "LO" button on the ECC. Fan speed should decrease until the fans are completely stopped. Releasing the "LO" button will return the calculation of fan speed to automatic BCM control.

ECC PROGRAM

DESCRIPTION:

During the display of BCM data on the Fuel Data Center. The ECC will display a two digit number which represents the ECC program number. This number represents various levels of heating and cooling effort. As F.8.0 first appears on the Fuel Data Center, the ECC will begin displaying the program number which is currently being used by the ECC system. As operating conditions change, this number will automatically change in response.

The automatic calculation of program number can be bypassed by a manual override feature using the Warmer and Cooler buttons. While in the F.8.0 mode pressing the Warmer button will force the program number to increase at a controlled rate until the value of "100" is reached. "100" represents the max heat mode of ECC operation. Pressing the cooler button will force the program number to decrease until the value of "0" is reached which represents the max A/C mode. This manual override of automatic program number calculation will continue until the F.8.0 mode is exited. This allows the service technician to control the program number to any number from "0" to "100" and simultaneously observe the reaction of any of the BCM data parameters.

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