AutoCodes – GMC – B3656 GMC

B3656 GMC Code - Electrical Power Take Off Control Switch Circuit High

Quick Answer

The Auxiliary Power Outlet (APO) Switch controls the operation of the Hybrid Control Module (HCM) APO state manager. Common causes include Faulty Auxiliary Power Outlet (APO) Switch, Auxiliary Power Outlet (APO) Switch harness is open or shorted, Auxiliary Power Outlet (APO) 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: B3656 GMC indicates Electrical Power Take Off Control Switch Circuit High.
Common causes: Common causes include Faulty Auxiliary Power Outlet (APO) Switch, Auxiliary Power Outlet (APO) Switch harness is open or shorted, Auxiliary Power Outlet (APO) 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 548

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

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Table of contents Created and updated by William Orellana on Mar 09, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code B3656 GMC Description

The Auxiliary Power Outlet (APO) Switch controls the operation of the Hybrid Control Module (HCM) APO state manager. The APO state manager commands one of three states from the Starter Generator Control Module (SGCM) (APO Off, APO Normal, APO Continuous). The APO switch is a momentary button, its output signal an input to an HCM analogue channel. Five volts are supplied to the switch and the returned voltage is measured relative to HCM signal ground to determine the switch state. A resistor network in the switch circuitry ensures that shorted high and low states can be diagnosed successfully. There are 2 valid voltage ranges of the return signal, one representing switch open, the other representing switch closed. If the voltage is lower than a threshold, a short low is indicated. Similarly, if the voltage is greater than the short high threshold, a short 'high' is indicated. The Diagnostic Trouble Code (DTC) sets if voltage is lower than a calibrated value, a short low is indicated or if the voltage is greater than a calibrated value the short high is indicated.

OBDII Code B3656 GMC - Electrical Power Take Off Control Switch Circuit High - AutoCodes.com — B3656 GMC Code - Electrical Power Take Off Control Switch Circuit High

What does this mean?

What are the Possible Causes of the DTC B3656 GMC?

Faulty Auxiliary Power Outlet (APO) Switch
Auxiliary Power Outlet (APO) Switch harness is open or shorted
Auxiliary Power Outlet (APO) Switch circuit poor electrical connection
Faulty Hybrid Control Module (HCM)

How to Fix the DTC B3656 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 B3656 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.

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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 B3656 GMC Code

1. What are the common symptoms of OBDII code B3656 GMC?

- Common symptoms include illuminated Check Engine Light, difficulty engaging the power take-off (PTO) system, or the PTO system not functioning properly.

2. What can cause the OBDII code B3656 GMC to trigger?

- The code can be triggered by a faulty electrical power take-off (PTO) control switch, damaged wiring or connectors in the PTO circuit, or a malfunctioning PTO control module.

3. How can I diagnose the OBDII code B3656 GMC at home?

- You can start by inspecting the PTO control switch and its wiring for any visible damage. Using a multimeter, you can test the switch and circuit for continuity and proper voltage.

4. What is the recommended repair for OBDII code B3656 GMC?

- The recommended repair involves replacing the faulty electrical power take-off (PTO) control switch, repairing any damaged wiring or connectors in the PTO circuit, or replacing the malfunctioning PTO control module.

5. Can I continue driving with the OBDII code B3656 GMC present?

- It is not recommended to continue driving with the code present, as it can lead to further damage to the power take-off (PTO) system and may affect the vehicle's performance.

6. How much does it typically cost to repair OBDII code B3656 GMC?

- The cost of repair can vary depending on the extent of the issue and the specific components that need to be replaced. It is advisable to consult a professional mechanic for an accurate estimate.

7. Are there any preventive measures to avoid OBDII code B3656 GMC in the future?

- Regularly inspecting and maintaining the power take-off (PTO) system, including the control switch and wiring, can help prevent issues that may lead to the code being triggered.

8. Can a DIY enthusiast fix the OBDII code B3656 GMC themselves?

- Depending on their skill level and access to tools, a DIY enthusiast may be able to diagnose and repair the issue related to the code. However, it is recommended to seek professional help for a proper diagnosis and repair.

9. Will resetting the OBDII code B3656 GMC make it go away permanently?

- Resetting the code may temporarily turn off the Check Engine Light, but if the underlying issue is not addressed, the code is likely to reappear. It is important to diagnose and repair the root cause of the problem.

10. Is OBDII code B3656 GMC specific to GMC vehicles only?

- While the code is specific to GMC vehicles, similar issues with the power take-off (PTO) control system can occur in other makes and models, leading to different OBDII codes.