GM Service Manual Online
For 1990-2009 cars only

Step

Action

Values

Yes

No

Important: Do not use the DTC tables for intermittent problems. A fault must be present in order to locate the problem. If a fault is intermittent, use of DTC tables may result in the replacement of good parts.

DEFINITION: The problem may or may not illuminate the malfunction indicator lamp (MIL) or store a DTC.

1

Were the Preliminary Checks performed?

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Go to Step 2

Go to Symptoms - Engine Controls

2

  1. Perform a careful inspection of any suspect circuits.
  2. Inspect for poor mating of the connector halves, or terminals not fully seated into the connector body.
  3. Inspect for improperly formed or damaged terminals.
  4. Inspect for poor terminal to wire connections. This requires removing the terminal from the connector body to inspect it.

Is a repair necessary?

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Go to Step 3

Go to Step 4

3

Repair the electrical connections, as needed.

Did you complete the repair?

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System OK

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4

Road test the vehicle with a voltmeter connected to a suspected circuit or a scan tool connected to the data link connector (DLC).

Did the voltmeter or the scan tool display an abnormal voltage or scan reading?

--

Go to Step 5

Go to Step 6

5

Replace the sensor in the affected circuit if a DTC was stored for this circuit.

Did you complete the replacement?

--

System OK

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6

Does an intermittent malfunction indicator lamp (MIL) or DTC occur?

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Go to Step 7

Go to Step 8

7

  1. Inspect for a faulty relay, electronic control module (ECM) driven solenoid, or switch.
  2. Inspect for improper installation of electrical devices, such as lights, 2-way radios, electric motors, etc.
  3. Inspect the ignition control wires for proper routing, away from ignition wires, ignition system components, and the generator.
  4. Inspect for a short-to-ground in the MIL circuit or the DLC test terminal.
  5. Inspect the ECM ground connections.
  6. Correct or repair the affected circuits, as needed.

Did you find and correct the condition?

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System OK

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8

  1. Inspect for a loss of DTC memory.
  2. Disconnect the throttle position (TP) sensor.
  3. Run the engine at idle until the MIL comes ON.
  4. Turn the ignition OFF.

Is DTC P0122 stored in memory?

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Go to Step 10

Go to Step 9

9

Replace the ECM. Refer to Engine Control Module Replacement .

Did you complete the replacement?

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System OK

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10

Does the vehicle stall while driving?

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Go to Step 11

Go to Step 12

11

Monitor the oxygen sensor (O2S) and the injector base pulse width with the scan tool.

Does the scan tool display a steady low voltage, about 0 mv, for the O2S sensor with the control module commanding an injector base pulse width of the value specified?

8 ms

Go to Step 9

Go to Step 12

12

  1. Inspect for an open diode across the A/C clutch and for other open diodes.
  2. Repair or replace any components, as needed.

Did you find and correct the condition?

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System OK

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