Test Description
WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2002 GMC Yukon XL, 2002 GMC Yukon, 2002 Chevrolet Tahoe, 2002 Chevrolet Suburban, and 2002 Chevrolet Avalanche. 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.
- 5: This step verifies that the HVAC control module data signal circuit is functioning.
- 6: This test verifies that the HVAC control module clock signal circuit is operating at the correct frequency.
DTC U1500
| Step | Action | Values | Yes | No |
|---|---|---|---|---|
| Schematic Reference: HVAC Schematics | ||||
| 1 | Did you perform the HVAC Diagnostic System Check? | - | Go to Step 2 | Go to Diagnostic System Check - HVAC Systems - Automatic |
| 2 | Test the HVAC control module data signal circuit for a short to voltage or an open. Refer to CIRCUIT TESTING
and WIRING REPAIRS
. Did you find and correct the condition? |
- | Go to Step 11 | Go to Step 3 |
| 3 | Test the HVAC control module data signal circuit for a short to ground. Refer to CIRCUIT TESTING
and WIRING REPAIRS
. Did you find and correct the condition? |
- | Go to Step 11 | Go to Step 4 |
| 4 | Test the HVAC control module clock signal circuit for a short to voltage, a short to ground, or an open. Refer to CIRCUIT TESTING
and WIRING REPAIRS
. Did you find and correct the condition? |
- | Go to Step 11 | Go to Step 5 |
| 5 | Measure the voltage from the HVAC control module data signal circuit to a good ground. Does the voltage measure near the specified value? |
1 Vdc | Go to Step 6 | Go to Step 7 |
| 6 | Measure the frequency from the HVAC control module clock signal circuit to a good ground. Does the frequency measure near the specified value? |
1.3 kHz | Go to Step 8 | Go to Step 7 |
| 7 | Inspect for poor connections at the harness connector of the HVAC control module. Refer to TESTING FOR INTERMITTENT AND POOR CONNECTIONS
and CONNECTOR REPAIRS
. Did you find and correct the condition? |
- | Go to Step 11 | Go to Step 9 |
| 8 | Inspect for poor connections at the harness connector of the auxiliary HVAC control module. Refer to TESTING FOR INTERMITTENT AND POOR CONNECTIONS
and CONNECTOR REPAIRS
. Did you find and correct the condition? |
- | Go to Step 11 | Go to Step 10 |
| 9 | Replace the HVAC control module. Refer to HVAC Control Module Replacement . Did you complete the repair? |
- | Go to Step 11 | - |
| 10 | Replace the auxiliary HVAC control module. Refer to HVAC Control Module Replacement - Auxiliary . Did you complete the repair? |
- | Go to Step 11 | - |
| 11 |
|
- | Go to Step 2 | System OK |