Corrections to Pages 6E1-A-4, A-5, A-34, A-52 and C1-12
FIGURE A-3 - ECM WIRING DIAGRAM (1 OF 2) - 1.5L (VIN 7) "R" CARLINE (CARB):
FIGURE A-4 - ECM WIRING DIAGRAM (2 OF 2) - 1.5L (VIN 7) "R" CARLINE (CARB):
6E1-A-4 1.5L (VIN 7) DRIVEABILITY AND EMISSIONS
CODE 21
THROTTLE POSITION SENSOR (TPS) AND IDLE SWITCH CIRCUIT
Circuit Description: 1.5L (VIN 7) "R" CARLINE (CARB)
The Throttle Position Sensor (TPS) provides a voltage signal that changes relative to the throttle valve. Signal voltage will vary from less than .80 volts at idle to about 4.5 volts at wide open throttle (WOT). The idle switch provides the ECM with information used to decide closed loop operation and indicates off-idle condition to the ECM. This switch is normally closed at idle and opens above 1800 RPM, which is then the off-idle condition. The TPS signal is one of the most important inputs used by the ECM for fuel control and for many of the ECM controlled outputs.
Test Description: Numbers below refer to circled numbers on the diagnostic chart.
1. These tests will determine if the idle switch portion of the circuit is at fault when a code 21 is set.
2. This step checks to see if Code 21 is the result of a hard failure or an intermittent condition. A Code 21 will set if:
* Both WOT and idle are detected for more than one second. OR
^ TPS is in OFF-IDLE or WOT position.
^ All of the above conditions present for 32 seconds.
^ Engine speed is between 500 and 600 rpm.
3. If the ECM recognizes the change of state, the ECM and CKTs 416 and 417 are OK.
4. This step isolates a faulty sensor, ECM, or an open CKT 452.
Diagnostic Aids:
A "Scan" tool displays throttle position in volts. Closed throttle voltage should be less than .80 volts. TPS voltage should increase at a steady rate as throttle is moved to WOT. A Code 21 will result if CKT 452 is open or CKT 417 is shorted to voltage. If Code 21 is intermittent, refer to Section "B".
CODE 54
MIXTURE CONTROL (M/C) SOLENOID CIRCUIT (SIGNAL VOLTAGE HIGH) 1.5L (VIN 7) "R" CARLINE (CARB)
Circuit Description:
Code 54 will be set if there is constant high voltage at ECM terminal "21". A shorted solenoid or shorted CKT 411 to 12V would cause the solenoid to remain in the full rich position, resulting in potential ECM damage, excessive fuel consumption, and excessive exhaust odor.
Test Description: Numbers below refer to circled numbers on the diagnostic chart.
1. Checks the M/C solenoid resistance to determine if the fault is in the solenoid, ECM harness, or ECM. A normal solenoid has about 20 to 32 ohms of resistance. The ECM is equipped with a fault protected quad driver. If the M/C solenoid is under 10 ohms, only the solenoid has to be replaced, not the ECM.
2. Checks to see if reason for high voltage to terminal "21" is a faulty ECM or a short to 12V in CKT 411. If the test light illuminates with both ends of harness disconnected, there is a short to 12V in CKT 411.
CHART C-1A
THROTTLE POSITION SENSOR (TPS) (ASSEMBLY FUNCTIONAL CHECK)
Circuit Description: 1.5L (VIN 7) "R" CARLINE (CARB) The Throttle Position Sensor (TPS) provides a voltage signal that changes relative to the throttle valve. Signal voltage will vary from less than .80 volts at idle to about 4.5 volts at wide open throttle (WOT). The idle switch provides the ECM with information used to decide closed loop operation and indicates the off-idle condition to the ECM. This switch is normally closed at idle and opens above 1800 RPM, which is then the off-idle condition. The TPS signal is one of the most important inputs used by the ECM for fuel control and for many of the ECM controlled outputs.
Diagnostic Aids:
A "Scan" tool displays throttle position in volts. Closed throttle voltage should be less than .80 volts. TPS voltage should increase at a steady rate as throttle is moved to WOT.