Test Description

The numbers below refer to the step numbers on the diagnostic table. See Fig 1-Fig 5 .

1. 4
   
   This step tests the headlamp dimmer switch high beam signal circuit for a short to ground.
2. 5
   
   This step tests the headlamp dimmer switch high beam signal circuit for a short to battery voltage.
3. 6
   
   This step tests the power feed circuit for the HDLP PWR relay.
4. 7
   
   This step tests the HDLP PWR relay.
5. 8
   
   This step tests the power feed circuit to the HDLP fuses.
6. 10
   
   This step test the DRL relay.
7. 15
   
   This step tests the headlamp dimmer switch high beam signal circuit for an open or short to voltage.

Fig 1: DTC B2600 Diagnostic Table (Steps 1-6)

Courtesy of GENERAL MOTORS CORP.

Fig 2: DTC B2600 Diagnostic Table (Steps 7-9)

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Fig 3: DTC B2600 Diagnostic Table (Steps 10-14)

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Fig 4: DTC B2600 Diagnostic Table (Steps 15-16)

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Fig 5: DTC B2600 Diagnostic Table (Steps 17-27)

Courtesy of GENERAL MOTORS CORP.