DTC 35

Code Chart 35:

IAC Circuit:

CIRCUIT DESCRIPTION:
Code 35 will set when the closed throttle engine speed is 200 rpm above or below the desired (commanded) idle speed for 50 seconds.

TEST DESCRIPTION: Numbers below refer to circled numbers on the diagnostic chart.

1. The Scan tools rpm control mode is used to extend and retract the IAC valve. The valve should move smoothly within the specified range. If the idle speed is commanded (IAC extended) too low (below 700 rpm), the engine may stall. This may be normal and would not indicate a problem. Retracting the IAC beyond its controlled range (above 1500 rpm) will cause a delay before the rpm's start dropping. This too is normal.

2. This test uses the Scan Tool to command the IAC controlled idle speed. The ECM issues commands to obtain commended idle speed. The node lights each should flash red and green to indicate a good circuit as the ECM issues commands. While the sequence of color is not important if either light is "OFF" or does not flash red and green, check the circuits for faults, beginning with poor terminal contacts.

DIAGNOSTIC AIDS:
^ A slow, unstable or fast idle, may be caused by a system problem that cannot be overcome by the IAC. Out of control range, IAC "SCAN" tool counts will be above 60 if idle is to low, and zero counts if idle is to high. The following checks should be made to repair a non-IAC system problem.
^ Vacuum Leak (High Idle) - If idle is to high, stop the engine. Fully extend the IAC tester. Start engine. If idle speed is above 800 rpm, locate and correct vacuum leak including PCV system. Also check for binding of throttle blade or linkage.
^ System lean (High Air Fuel Ratio) - Idle speed may be too high or too low. Engine speed may vary up and down, disconnecting IAC does not help. May set Code 44. "Scan" and/or voltmeter will read an oxygen sensor output less than 300 mV (0.3 volt). Check for low regulated fuel pressure, water in the fuel or a restricted injector.
^ System rich (Low Air/Fuel Ratio) - Idle speed too low. "Scan" counts usually above 80. System obviously rich and may exhibit black smoke exhaust. "Scan" tool and/or voltmeter will read an oxygen sensor signal fixed above 800 mV (0.8 volt). Check for high fuel pressure or possibly an injector leaking or sticking.
^ Throttle Body - Remove IAC and inspect bore for foreign material or evidence of IAC pintle dragging the bore.
^ IAC Valve Electrical Connections - IAC Valve electrical connections should be checked for proper contact.
^ PCV Valve - An incorrect or faulty PCV valve may result in an incorrect idle speed.
^ Rough, Unstable, or Incorrect Idle, Stalling
^ If intermittent poor driveability or idle symptoms are resolved by disconnection the IAC, carefully recheck connections, valve terminal resistance, or replace IAC.