DTC 35

Fig. 021 - Chart - Code 35 Shorted ISC Motor Throttle Switch:

CODE 35, IDLE SPEED CONTROL CIRCUIT

Code 35 says that the ECM sees the voltage at ECM Term. "8" continually low with the throttle open which indicates that the circuit through the ISC throttle switch is grounded. The voltage should go to 12 volts when the switch opens. A grounded circuit could cause stalling because the ECM would retract the ISC plunger completely resulting in low idle speed.



1. Separates a shorted ISC throttle switch from a TPS/MAP/VAC problem. If on a restart, at idle, the "SERVICE ENGINE SOON" light appears, the fault is in the TPS/MAP/VAC circuits. Due to ECM calibration, a Code 35 could appear before a 21, 32 or 34 with a faulty TPS or faulty MAP/VAC sensor analog low (ground) circuit.
2. This step checks for an open analog low in circuit to ECM or ECM itself. If the test light is "ON", the fault is in the TPS circuit even though the conditions above may have set a 35.
3. 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 the TPS is depressed.
4. This step checks for a malfunctioning ISC nose switch with the connector off of the ISC motor. An ohmmeter should read infinite resistance (open circuit) when the throttle is moved off of the nose switch (and virtually zero with it closed).
5. With the harness disconnected, the voltage from Terminal 'B' to 'A' should be about 12V.