AutoCodes – GMC – P071A GMC

P071A GMC Code - Transmission Tow Mode Switch Circuit

Quick Answer

Tow/haul mode enables the operator to achieve enhanced shift performance when towing or hauling a load. Common causes include Faulty Transmission Tow Mode Switch, Transmission Tow Mode Switch harness is open or shorted, Transmission Tow 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: P071A GMC indicates Transmission Tow Mode Switch Circuit.
Common causes: Common causes include Faulty Transmission Tow Mode Switch, Transmission Tow Mode Switch harness is open or shorted, Transmission Tow 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 439

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 Jul 29, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P071A GMC Description

Tow/haul mode enables the operator to achieve enhanced shift performance when towing or hauling a load. When tow/haul mode is selected, the tow/haul switch input signal to the Body Control Module (BCM) is momentarily toggled from 12 volts to zero volts. The BCM then sends a signal out on the serial data line to the Transmission Control Module (TCM) to increase transmission line pressure and extend the time between upshifts. Selecting the tow/haul switch again disables tow/haul mode and returns the transmission to a normal shift pattern.

OBDII Code P071A GMC - Transmission Tow Mode Switch Circuit - AutoCodes.com — P071A GMC Code - Transmission Tow Mode Switch Circuit

What does this mean?

What are the Possible Causes of the DTC P071A GMC?

Faulty Transmission Tow Mode Switch
Transmission Tow Mode Switch harness is open or shorted
Transmission Tow Mode Switch circuit poor electrical connection
Faulty Body Control Module (BCM)

How to Fix the DTC P071A 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 P071A 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 P071A GMC code?

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Information for Specific GMC Models

P071A 2014 GMC Sierra — Transmission Tow Mode Switch Circuit
P071A 2015 GMC Sierra — Transmission Tow Mode Switch Circuit
P071A 2016 GMC Sierra — Transmission Tow Mode Switch Circuit
P071A 2017 GMC Sierra — Transmission Tow Mode Switch Circuit
P071A 2018 GMC Sierra — Transmission Tow Mode Switch Circuit

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 P071A GMC Code

1. What does the OBDII code P071A on a GMC vehicle mean?

P071A indicates a problem in the Transmission Tow Mode Switch Circuit, which controls the tow/haul mode for improved transmission performance during towing or heavy loads.

2. What are the common symptoms of the P071A code?

Symptoms may include the tow/haul mode not engaging, the tow mode indicator light not functioning, decreased towing performance, or the check engine light turning on.

3. What causes the P071A code to appear?

Common causes include a faulty tow/haul mode switch, damaged wiring or connectors in the tow mode circuit, or a malfunction in the transmission control module (TCM).

4. Can I still drive my GMC with the P071A code active?

Yes, you can drive the vehicle, but the tow/haul mode may not function, which can affect towing performance and place extra strain on the transmission.

5. How is the P071A code diagnosed?

A technician will use a scan tool to confirm the code, inspect the tow/haul mode switch, check the wiring and connectors for damage, and test the circuit for proper voltage and continuity.

6. How do I fix the P071A code on my GMC?

Repairs may include replacing the tow/haul mode switch, repairing or replacing damaged wiring or connectors, or reprogramming or replacing the transmission control module if necessary.

7. What tools are needed to fix the P071A code?

Tools typically include a diagnostic scan tool, a multimeter for testing the circuit, and basic tools for accessing and replacing the tow/haul mode switch or wiring.

8. How much does it cost to repair the P071A code?

Repair costs vary depending on the cause but can range from $100 to $300 for switch or wiring repairs, while TCM replacement can cost $500 or more.

9. Can the P071A code be prevented?

Regular maintenance, inspecting the tow/haul mode switch and wiring for wear, and avoiding excessive strain on the transmission can help prevent the code from appearing.

10. Does a faulty tow/haul mode switch always trigger the P071A code?

Not always. While a faulty switch is a common cause, issues with wiring, connectors, or the TCM can also trigger the code, requiring thorough diagnosis.