AutoCodes – Cadillac – P15B9 Cadillac

P15B9 Cadillac Code - Electric A/C Compressor Control Module Ignition On/Start Switch Circuit Low Voltage

Quick Answer

The Body Control Module (BCM) controls the ignition run relay through the control circuit by applying voltage to the circuit. Common causes include Faulty Hybrid Powertrain Control Module 2, Hybrid Powertrain Control Module 2 harness is open or shorted, Hybrid Powertrain Control Module 2 circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P15B9 Cadillac indicates Electric A/C Compressor Control Module Ignition On/Start Switch Circuit Low Voltage.
Common causes: Common causes include Faulty Hybrid Powertrain Control Module 2, Hybrid Powertrain Control Module 2 harness is open or shorted, Hybrid Powertrain Control Module 2 circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 1,087

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Jan 03, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P15B9 Cadillac Description

The Body Control Module (BCM) controls the ignition run relay through the control circuit by applying voltage to the circuit. The ignition circuit is energized when the vehicle power mode is Vehicle ON or Vehicle in Service Mode. The hybrid powertrain control module 2 sends the vehicle power mode status in a serial data message to the battery charger control module, A/C compressor, battery energy control module, fuel pump control module and the Transmission Control Module (TCM).

OBDII Code P15B9 Cadillac - Electric A/C Compressor Control Module Ignition On/Start Switch Circuit Low Voltage - AutoCodes.com — P15B9 Cadillac Code - Electric A/C Compressor Control Module Ignition On/Start Switch Circuit Low Voltage

What does this mean?

What are the Possible Causes of the DTC P15B9 Cadillac?

Faulty Hybrid Powertrain Control Module 2
Hybrid Powertrain Control Module 2 harness is open or shorted
Hybrid Powertrain Control Module 2 circuit poor electrical connection

How to Fix the DTC P15B9 Cadillac?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P15B9 Cadillac code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P15B9 Cadillac Code

1. What does the OBDII code P15B9 mean on a Cadillac?

The P15B9 code indicates a low voltage issue in the Electric A/C Compressor Control Module Ignition On/Start Switch Circuit.

2. What are common symptoms of the P15B9 code?

Symptoms may include reduced or no A/C cooling, an illuminated check engine light, and possible electrical issues in the A/C system.

3. What causes the P15B9 code to appear?

Common causes include a faulty electric A/C compressor control module, damaged wiring or connectors, a weak battery, or a malfunctioning ignition switch.

4. Can a low battery voltage trigger the P15B9 code?

Yes, a weak or failing battery can cause insufficient voltage, leading to this code.

5. How can I diagnose the P15B9 code?

Start by checking the battery voltage, inspecting wiring and connectors for damage, and testing the A/C compressor control module for faults.

6. Is it safe to drive with the P15B9 code?

While it might be safe to drive, the A/C system may not work properly, and the issue could lead to further electrical problems if left unaddressed.

7. How do I fix the P15B9 code?

Repairs may include replacing damaged wiring, repairing or replacing the A/C compressor control module, or addressing battery and ignition switch issues.

8. Can a bad ignition switch cause the P15B9 code?

Yes, a malfunctioning ignition switch can disrupt voltage to the circuit, triggering this code.

9. How much does it cost to repair the P15B9 code?

Repair costs can range from $100 to $1,000 depending on whether the issue is with wiring, the control module, or other components.

10. Do I need a professional to fix the P15B9 code?

If you're experienced with electrical diagnostics, you may be able to fix it yourself. However, for complex issues, a professional mechanic is recommended.