These trucks need 55-61 psi fuel pressure, Yours is in range, Symptom Definition :
Engine starts but will not run at idle. Engine runs if accelerator is held at part throttle.
Possible Causes & Corrections:
Ã Problem is most likely in Idle Air Control (IAC) system. See DIAGNOSTIC AIDS in CODE 35 chart in appropriate TESTS W/CODES article in this section.
Ã Check EGR system.
Ã Check park/neutral switch.
Ã Disconnect MAP sensor. If condition is corrected, replace sensor. You also need to check the oil pressure switch, if it's bad it will not allow the truck to run. It's checked by removing the fuel pump relay while it's running, if it continues to run the switch is ggod if it dies it's bad. Test IAC like this:
Idle Air Control (IAC) Motor
1.Disconnect harness connector to motor. Check resistance across IAC coil terminals "A" to "B" and "C" to "D". See Fig. 5. Resistance should be 40-80 ohms. If okay, go to next step. If resistance is not as specified, replace IAC motor. 2.Check resistance between IAC terminals "B" to "C" and "A" to "D". Resistance should be infinite. If resistance is not as specified, replace IAC motor.
NOTE: Functional testing of Idle Air Control (IAC) motor requires a scan tester capable of cycling ECM output devices (bidirectional) or a special IAC Driver and Node Light Set (222L or J-37027). Flow charts in TESTS W/CODES articles in this section may refer to Tech 1 tester, General Motors' bidirectional tester.
Monday, November 8th, 2010 AT 10:25 PM