AutoCodes – GMC – P15A1 GMC

P15A1 GMC Code - Fuel Economy Mode Switch Performance

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: P15A1 GMC indicates Fuel Economy Mode Switch Performance.
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 4,853

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 P15A1 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 P15A1 GMC - Fuel Economy Mode Switch Performance - AutoCodes.com — P15A1 GMC Code - Fuel Economy Mode Switch Performance

What does this mean?

What are the Possible Causes of the DTC P15A1 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 P15A1 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 P15A1 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 P15A1 GMC code?

Need more information on how to fix the P15A1 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 P15A1 GMC Code

1. What are the common symptoms of OBDII code P15A1 GMC (Fuel Economy Mode Switch Performance)?

The common symptoms include reduced fuel economy, engine performance issues, and the illumination of the Check Engine light.

2. What are the possible causes of OBDII code P15A1 GMC?

Possible causes of this code include a faulty fuel economy mode switch, wiring issues, or problems with the switch circuit.

3. How can I diagnose the cause of OBDII code P15A1 GMC?

Diagnosing this code typically involves checking the fuel economy mode switch for proper operation, inspecting related wiring for damage, and testing the switch circuit for continuity.

4. Can a DIYer repair OBDII code P15A1 GMC?

While some DIYers may be able to address this issue by replacing the fuel economy mode switch or repairing wiring, it is recommended to consult a professional for accurate diagnosis and repair.

5. Is it safe to continue driving with OBDII code P15A1 GMC active?

It is generally safe to drive with this code, but it is important to address the underlying issue promptly to prevent potential fuel economy and performance problems.

6. How much does it cost to repair OBDII code P15A1 GMC?

The cost of repairing this code can vary depending on the cause of the issue, labor rates, and parts needed. It is advisable to obtain quotes from different mechanics or repair shops.

7. Can a faulty fuel economy mode switch be repaired, or does it need to be replaced?

In most cases, a faulty fuel economy mode switch will need to be replaced to resolve OBDII code P15A1 GMC and restore proper functionality.

8. Are there any preventive maintenance tips to avoid OBDII code P15A1 GMC?

Regularly inspecting the fuel economy mode switch, checking for wiring damage, and addressing any related issues promptly can help prevent the occurrence of this code.

9. Will resetting the Check Engine light clear OBDII code P15A1 GMC?

Resetting the Check Engine light may temporarily clear the code, but it will reappear if the underlying issue causing OBDII code P15A1 GMC is not addressed.

10. How long does it take to repair OBDII code P15A1 GMC?

The repair time for this code can vary depending on the exact cause of the issue and the complexity of the repair process. It is advisable to consult with a professional for a more accurate estimate.