LEMON Manuals: Even more car manuals for everyone
Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1385 (Engine Control System Diagnosis (DTC P0505 To DTC P2196) -- 1.8L (LV6)) >> Diagnosis >> DTC P0505 >> Test Description

Test Description

WARNING: This page is about a different car, the 2004 Pontiac Vibe. However, it is still accessible from the selected car via links, so may be relevant.

The numbers below refer to the step numbers on the diagnostic table.

  1. 7:  This step simulates the pulse width modulated (PWM) signal supplied to the IAC valve by the PCM by rapidly grounding and ungrounding terminal 1 of the IAC valve.
  2. 9:  The most likely cause of no power is an open circuit condition between the IAC valve connector terminal 2 and the splice. A shorted or inoperative EFI relay circuit will cause a no-start condition.
DTC P0505

Step Action Yes No
Schematic Reference:  Engine Controls Schematics 
Connector End View Reference:  Powertrain Control Module (PCM) Connector End Views  or  Engine Controls Connector End Views 
1 Did you perform the Diagnostic System Check-Engine Controls? Go to Step 2  Go to Diagnostic System Check - Engine Controls
2
  1. Start and idle the engine until the engine reaches a normal operating temperature.
  2. Using a scan tool, store the Freeze Frame and DTC information.
  3. Turn OFF the ignition and wait 30 seconds.
  4. Turn ON the ignition, with the engine OFF.
  5. Perform the scan tool Clear DTC Information function.
  6. Start and idle the engine.
  7. Wait 60 seconds, then check for stored DTCs.
Does this DTC reset?		 Go to Step 4  Go to Step 3 
3 Is there an idle quality concern? Go to Rough, Unstable, or Incorrect Idle and Stalling Go to Diagnostic Aids
4
  1. Inspect the positive crankcase ventilation (PCV) system for the following conditions:
  2. Repair or replace as necessary.
Did you find and correct the condition?		 Go to Step 13  Go to Step 5 
5
  1. Turn OFF the ignition.
  2. Disconnect the IAC valve electrical connector.
  3. Turn ON the ignition, with the engine OFF.
  4. Using a test lamp connected to ground, probe terminal 2 of the IAC valve connector on the harness side.
Does the test lamp illuminate?		 Go to Step 6  Go to Step 9 
6 Using a test lamp connected to B+, probe terminal 3 of the IAC valve connector.
Does the test lamp illuminate?		 Go to Step 7  Go to Step 10 
7 
  1. Turn OFF the ignition.
  2. Jump terminal 2 of the IAC valve connector on the harness side to terminal 2 of the IAC valve connector with a fused jumper wire.
  3. Jump terminal 3 of the IAC valve connector on the harness side to terminal 3 of the IAC valve connector with a fused jumper wire.
  4. Connect a fused jumper wire to terminal 1 of the IAC valve-not the harness.
  5. Insulate the terminal 1 jumper from contact to ground.
  6. Start and idle the engine.
  7. With the engine idling, repeatedly touch the terminal 1 jumper to battery ground with a rapid ON-OFF motion.
Does engine speed increase as the terminal 1 jumper is rapidly grounded ON and OFF?		 Go to Step 8  Go to Step 11 
8
  1. Turn OFF the ignition.
  2. Remove all jumpers.
  3. Disconnect the PCM connector containing the IAC valve open control circuit.
  4. Check terminal 1 of the IAC valve open control circuit for a grounded, open, or shorted to voltage circuit.
  5. Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems.
Was a circuit repair made?		 Go to Step 13  Go to Step 12 
9 
  1. Locate the cause of no power to the IAC valve connector. Refer to the Test Description.
  2. Repair as necessary. Refer to Wiring Repairs in Wiring Systems.
Is the action complete?		 Go to Step 13  -
10 Repair the open IAC valve ground circuit. Refer to Wiring Repairs in Wiring Systems.
Is the action complete?		 Go to Step 13  -
11
IMPORTANT: The IAC valve seals the coolant passage of the throttle body.
Replace the IAC valve. Refer to Idle Air Control (IAC) Valve Replacement (AWD) .Is the replacement complete?		 Go to Step 13  -
12 Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement .
Is the replacement complete?		 Go to Step 13  -
13
  1. Use the scan tool in order to clear the DTCs.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.
Is DTC P0505 set in Last Test Failed?		 Go to Step 2  Go to Step 14 
14 With a scan tool, observe the stored information, Capture Info.
Does the scan tool display any DTCs that you have not diagnosed?		 Go to Diagnostic Trouble Code (DTC) List System OK
scientia non olet · About LEMON Manuals