AutoCodes – GMC – P15A0 GMC

P15A0 GMC Code - Fuel Economy Mode Switch Circuit High Voltage

Quick Answer

The Engine Control Module (ECM) supplies 5 V reference voltage, through the 5 V reference voltage circuit, to the S87 fuel economy mode switch. Common causes include Faulty Fuel Economy Mode Switch, Fuel Economy Mode Switch harness is open or shorted, Fuel Economy Mode Switch 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: P15A0 GMC indicates Fuel Economy Mode Switch Circuit High Voltage.
Common causes: Common causes include Faulty Fuel Economy Mode Switch, Fuel Economy Mode Switch harness is open or shorted, Fuel Economy Mode Switch 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 6,021

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 02, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P15A0 GMC Description

The Engine Control Module (ECM) supplies 5 V reference voltage, through the 5 V reference voltage circuit, to the S87 fuel economy mode switch. The 5 V reference voltage causes current to flow through a series of resistors in the switch to the switch ground circuit. The ECM monitors the reference voltage through a discrete fuel economy mode switch signal circuit. When the switch button is momentarily pressed, the switch contacts allow the 5 V reference voltage to by-pass one of the resistors. The ECM detects the resulting voltage drop as a fuel economy mode request and sends a GMLAN message to the Transmission Control Module (TCM) indicating the request. When the TCM receives the request, throttle progressions and transmission shift points are modified to optimize fuel efficiency. The Instrument Panel Cluster (IPC) also receives the fuel economy mode request message from the ECM and illuminates the fuel economy mode indicator lamp. The fuel economy mode switch must be pressed for between 0.094-1.5 s to activate the fuel economy mode.

OBDII Code P15A0 GMC - Fuel Economy Mode Switch Circuit High Voltage - AutoCodes.com — P15A0 GMC Code - Fuel Economy Mode Switch Circuit High Voltage

What does this mean?

What are the Possible Causes of the DTC P15A0 GMC?

Faulty Fuel Economy Mode Switch
Fuel Economy Mode Switch harness is open or shorted
Fuel Economy Mode Switch circuit poor electrical connection

How to Fix the DTC P15A0 GMC?

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 P15A0 GMC 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.

Need more information about the P15A0 GMC code?

Need more information on how to fix the P15A0 GMC code? Get Access to Factory Service Manuals

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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 P15A0 GMC Code

1. What does the OBDII code P15A0 mean on a GMC?

P15A0 indicates a high voltage issue in the Fuel Economy Mode Switch Circuit, often related to a malfunction in the switch or its associated wiring.

2. What are the common symptoms of code P15A0 on a GMC?

Symptoms include an illuminated check engine light, inability to activate fuel economy mode, and potentially reduced fuel efficiency.

3. What causes the P15A0 code to appear on a GMC vehicle?

Common causes include a faulty fuel economy mode switch, damaged wiring or connectors, or a malfunctioning body control module (BCM).

4. How do I diagnose the P15A0 code on my GMC?

Start by inspecting the fuel economy mode switch and its wiring for damage or corrosion. Use a multimeter to check for proper voltage and continuity in the circuit.

5. Can I drive my GMC with the P15A0 code active?

Yes, you can usually drive with this code active, but you may experience reduced fuel efficiency and be unable to use fuel economy mode.

6. How do I fix the P15A0 code on a GMC vehicle?

Fixes may include replacing the faulty fuel economy mode switch, repairing damaged wiring or connectors, or reprogramming the body control module if necessary.

7. How much does it cost to repair the P15A0 code on a GMC?

The repair cost varies, but replacing the fuel economy mode switch typically costs $50â€“$200, while wiring repairs or BCM reprogramming could cost more.

8. Can a dead battery cause the P15A0 code on a GMC?

A dead or weak battery can sometimes cause electrical issues, but itâ€™s not a common cause of the P15A0 code. Check the circuit before suspecting the battery.

9. Does the P15A0 code affect vehicle performance?

It usually doesnâ€™t affect overall performance but may reduce fuel efficiency and prevent access to fuel-saving features.

10. Can I clear the P15A0 code without fixing the issue?

Clearing the code with a scan tool may temporarily turn off the check engine light, but the issue will likely reoccur until the underlying problem is resolved.