GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

1

Important: Before clearing DTCs use the scan tool Capture Info to record freeze frame and failure records for reference, as data will be lost when Clear Info function is used.

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

--

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

2

Install scan tool.

Does scan tool display a DTC Offset greeter than or less than the specified values?

+2.5 or -2.5

Go to Step 4

Go to Step 3

3

DTC is intermittent. If no additional DTCs are stored, refer to Diagnostic Aids. If additional DTCs were stored the applicable table(s) first.

Are additional DTCs stored?

--

Go to the Applicable DTC Table

Go to Diagnostic Aids

4

Are there any other DTCs set?

--

Go to the Applicable DTC Table

Go to Step 5

5

Clear all codes and reset injection timing until TDC Offset is between specified values. Refer to Fuel Injection Pump Top Dead Center Offset Adjustment .

Is timing within specified value?

-.25 to -.75

Go to Step 8

Go to Step 6

6

Check the crankshaft position sensor for the following.

    • Proper installation.
    • Loose or broken sensor mounting tab.

Was a repair performed?

--

Go to Step 8

Go to Step 7

7

Replace the PCM.

Important: If the PCM is faulty, the new PCM must be programmed. Refer to Powertrain Control Module Replacement/Programming .

Is the action complete?

--

Go to Step 8

--

8

  1. Using the Scan Tool, select DTC, Clear Info.
  2. Start engine and idle at normal operating temperature.
  3. Select DTC, Specific, then enter the DTC number which was set.
  4. Operate vehicle within the conditions for setting this DTC as specified in the supporting text.

Does the Scan Tool indicate that this diagnostic Ran and Passed?

--

Go to Step 9

Go to Step 2

9

Using the Scan Tool, select Capture Info, Review Info.

Are any DTCs displayed that have not been diagnosed?

--

Go to the Applicable DTC Table

System OK