Invalid Test APCM Functioning
The P1502 code indicates that the Auxiliary Powertrain Control Module (APCM) has detected an invalid self-test result. This typically points to an internal fault within the APCM or a communication issue with the main PCM. The APCM manages auxiliary engine functions like idle speed, alternator output, and cooling fans. A failed test can lead to erratic engine behavior.
1. Symptoms You Will Notice
- Check Engine Light illuminated
- Engine stalling or rough idle
- Intermittent electrical issues (fans, alternator)
- Reduced fuel economy
2. Most Common Causes
- Faulty Auxiliary Powertrain Control Module (APCM)
- Corroded or damaged wiring/connectors to APCM
- Communication error between PCM and APCM
- Low battery voltage or charging system issue
3. Step-by-Step Diagnosis
Step 1: Scan for additional codes and record freeze frame data.
Step 2: Inspect APCM connectors and wiring for corrosion or damage.
Step 3: Check battery voltage and charging system output.
Step 4: Perform APCM self-test using a professional scan tool.
Step 5: If tests fail, replace APCM and reprogram if necessary.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended as the APCM controls critical engine functions; driving may cause stalling or electrical failures.
How much does it cost to fix?▼
Repair costs range from $150 to $400, including diagnosis and APCM replacement if needed.
5. Commonly Affected Makes
This is a manufacturer-specific code. The exact manufacturer is not confirmed in our current database.