Code 35, Idle Speed Control (ISC) CKT (3.8L)
Code 35 indicates the ECM has seen voltage at ECM terminal "8" continually low with throttle open. This indicates the circuit through ISC throttle switch is grounded. Voltage should go to 12 volts when switch opens. A grounded circuit will cause stalling because the ECM will retract ISC plunger completely resulting in low idle speed.
NOTE:
The following step numbers refer to the numbers in the accompanying flow chart(s).
- This step separates a shorted ISC throttle switch from a TPS/MAP/VAC problem. If the "SERVICE ENGINE SOON" light appears at idle on a restart, fault is in TPS/MAP/VAC circuits. Due to ECM calibration, a Code 35 could appear before a Code 21, 32 or 34 with a faulty TPS or faulty MAP/VAC sensor ground circuit.
- This step checks for an open ground in circuit 452 to the ECM or the ECM itself. If test light is on, fault is in the TPS circuit even though conditions above may have set a Code 35.
- This test verifies an ISC throttle switch failure. Raising RPM above 1200 takes the throttle off contact with the ISC. It also keeps a Code 21 from being set when TPS is depressed.
- This step checks for a malfunctioning ISC nose switch with the connector off the ISC motor. An ohmmeter should read infinite resistance (open circuit) when the throttle is moved off the nose switch (and virtually zero with it closed).
- With the harness disconnected, voltage from terminal "B" to "A" should be about 12 volts.