This diagnostic test indicates if the A/C request circuit is shorted to voltage. This is done by comparing the A/C Request line (CKT 603) to the serial data received from the HVAC controller. If A/C is not requested by serial data and the A/C Request line (CKT 603 ) is high, voltage present, then DTC P1538 is set.
• | DTC P1605 not set. |
• | A/C compressor not requested by the HVAC programmer via serial data. |
A/C request line high continuously for 20 seconds.
• | Disable the A/C compressor. |
• | The Malfunction Indicator Lamp (MIL) will not illuminate. |
• | No message will be displayed. |
• | A History DTC will clear after forty consecutive warm-up cycles with no failures of any non-emission related diagnostic test. |
• | A Last Test Failed (current) DTC will clear when the diagnostic runs and does not fail. |
• | Use a scan tool to clear DTCs. |
• | Interrupting PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Clearing Diagnostic Trouble Codes in PCM Description and Operation. |
Step | Action | Value(s) | Yes | No |
---|---|---|---|---|
1 | Was the On-Board Diagnostic (OBD) System Check performed? | -- | Go to A Powertrain On Board Diagnostic (OBD) System Check | |
2 |
Has this DTC set? | -- | Fault not present. Refer to Diagnostic Aids | |
3 | Using a scan tool view the A/C Request display. Does A/C Request display Yes? | -- | ||
4 |
Does A/C Request display Yes? | -- | ||
5 |
Does A/C Request display Yes? | -- | ||
6 |
Is the voltage more than the value specified? | 0.5 volts | ||
7 | Repair the short to voltage on CKT 762. Is the repair complete? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | -- |
8 | Repair the short to voltage on CKT 603. Is the repair complete? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | -- |
9 | Replace the HVAC programmer. Refer to Section 1, Heating and Air Conditioning . Is the replacement complete? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | -- |
10 | Replace the PCM. Refer to PCM Replacement/Programming . Is the replacement complete? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | -- |