AutoCodes – GMC – P1651 GMC

P1651 GMC Code - PCM Output Controls Fault

Quick Answer

The Quad Driver Module (QDM) is an electronic switch that completes a ground circuit when switched on. Common causes include Faulty Powertrain Control Module (PCM), Powertrain Control Module harness is open or shorted, Powertrain Control Module 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: P1651 GMC indicates PCM Output Controls Fault.
Common causes: Common causes include Faulty Powertrain Control Module (PCM), Powertrain Control Module harness is open or shorted, Powertrain Control Module 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 5,907

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 12, 2021

Description
Possible Causes
How To Fix
Cost to Diagnose
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Code P1651 GMC Description

The Quad Driver Module (QDM) is an electronic switch that completes a ground circuit when switched on. The QDM independently controls 4 separate outputs. A load is connected between battery voltage and the QDM allowing QDM driver to control the output. Each QDM has a fault detection logic that compares its input and output voltages. The logic expects to measure less than 3 volts when the QDM is on and greater than 7 volts when off. The QDM has only one fault that will detect a fault on any of the 4 outputs. The scan tool can be used to cycle the outputs on and off. It can also perform automated test which can isolate the faulty circuit.
The Diagnostic Trouble Code (DTC) P1650 and P1651 will set if there is an open, short to ground or short to voltage on any of the QDM output circuits, faulty MIL circuit, faulty upshift light circuit, faulty cooling fan relay circuit or A/C relay circuit. Fault detected for 5 seconds will set P1651. Fault detected for 20 seconds will set P1650. The QDM circuit is continuously checked when the engine is running.
The Quad Driver Module (QDM) is part of the Powertrain Control Module (PCM).

OBDII Code P1651 GMC - PCM Output Controls Fault - AutoCodes.com — P1651 GMC Code - PCM Output Controls Fault

What does this mean?

What are the Possible Causes of the DTC P1651 GMC?

Faulty Powertrain Control Module (PCM)
Powertrain Control Module harness is open or shorted
Powertrain Control Module circuit poor electrical connection

How to Fix the DTC P1651 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 P1651 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.