DTC 35

Fig. 082 - Wiring Diagram for Code 35 Idle Speed Error. VIN R:

CODE 35

IDLE SPEED ERROR

2.5L (VIN R) VIN U (2.5L) "A & N" SERIES (TBI)

Circuit Description:
Code 35 will set when the closed throttle engine speed is 150 rpm above or below the desired idle speed for 20 seconds.

Fig. 081 Chart - Code 35 Idle Speed Error:

Test Description:
Numbers below refer to circled numbers on the diagnostic chart.
1. Continue with test, even if engine will not idle. If idle is too low, "Scan" tool will display 80 or more counts, or steps. If idle is high, it will display "O" counts. Occasionally an erratic or unstable idle may occur. Engine speed may vary 200 rpm or more up and down. Disconnect the IAC valve. If the condition is unchanged, the IAC valve is not at fault.
2. When the engine was stopped, the IAC valve retracted (more air) to a fixed "Park" position for increased air flow and idle speed during the next engine start. This test determines if IAC valve is functioning.
3. Be sure to disconnect the IAC valve prior to grounding the diagnostic test terminal. The test light will confirm the ECM signals by a steady or flashing light on all circuits.
4. There is a remote posibility that one of the circuits is shorted to voltage, which would have been indicated by a steady light. Disconnect ECM and turn the ignition "ON" and probe terminals to check for this condition.

Diagnostic Aids:
A slow, unstable idle may be caused by a system problem that cannot be overcome by the IAC valve. "Scan" tool counts will be above 60 counts if too low, and zero counts if too high.
If idle is too high, stop the engine. Turn ignition "ON" and ground diagnostic terminal. Wait 30-45 seconds for IAC valve to seat, then disconnect IAC valve. Start engine. If idle speed is above 800 rpm, locate and correct vacuum leak.
a. System too lean (High Air/Fuel Ratio)
The idle speed may be too high or too low. Engine speed may vary up and down and disconnecting the IAC valve does not help. Code 44 may be set.
"Scan" tool and/or voltmeter will read an oxygen sensor output less than 300 mV (.3 volts). Check for low regulated fuel pressure or water in fuel. A lean exhaust, with an oxygen sensor output fixed above, 800 mV (.8 volts) will be a contaminated sensor, usually from silicone. This may also set a Code 45.
b. System too rich (Low Air/Fuel Ratio)
The idle speed will be too low. "Scan" tool counts will usually be above 80. System is obviously rich and may exhibit black smoke in exhaust.
"Scan" tool and/or voltmeter will read an oxygen sensor signal fixed above 800 mV (.8 volt).
Check for high fuel pressure or leaking or sticking injector.
c. Throttle Body
Remove IAC valve and inspect bore for foreign material or evidence of IAC valve dragging in the bore.
d. IAC Valve Connections
IAC valve connections should be carefully checked for proper contact.
e. PCV Valve
An incorrect or faulty PCV valve may result in an incorrect idle speed.
f. Refer to "Rough, Unstable, Incorrect Idle or Stalling" in "DIAGNOSIS BY SYMPTOMS"