90 Quattro 20V L5-2309cc 2.3L DOHC (7A) (1990)
SUPPLY VOLTAGE AND CIRCUIT CONTINUITY CHECK
1.
Leave potentiometer harness connector disconnected.
2.
Connect DVM between harness connector terminals #1 and #2.
3.
Turn ignition ON and note voltage.
^
Voltage should be approx. 5 volts.
4.
Check voltage between harness connector terminals #1 and #3.
^
Voltage should be approx. 5 volts.
If either voltage value is not obtained, check for:
a. Open or grounded circuit between harness connector (terminals #1, #2, & #3) and ECU (terminals 6A, 8A, and 7A respectively).
b. Open or grounded circuit between potentiometer harness connector terminal #2 and idle switch terminal #2 (Brn/Grn wire).
c. Open or grounded circuit between idle switch terminal #1 and ECU terminal 9A (Grn/Violet wire).
Make any necessary repairs and re-check.
If no wiring problems are found and there is no voltage reading in steps 3 or 4, or if voltage is greater than 5.5 volts, then the ECU is faulty.