AutoCodes – GMC – P0852 GMC

P0852 GMC Code - Park/Neutral Position Switch Circuit High Voltage

Quick Answer

The transmission manual shift shaft switch assembly, also known as the Internal Mode Switch (IMS), is a sliding contact switch attached to the manual shift shaft inside the transmission case. Common causes include Faulty Transmission Internal Mode Switch (IMS), Transmission Internal Mode Switch harness is open or shorted, Transmission Internal 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: P0852 GMC indicates Park/Neutral Position Switch Circuit High Voltage.
Common causes: Common causes include Faulty Transmission Internal Mode Switch (IMS), Transmission Internal Mode Switch harness is open or shorted, Transmission Internal 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 2,501

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Aug 03, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
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Code P0852 GMC Description

The transmission manual shift shaft switch assembly, also known as the Internal Mode Switch (IMS), is a sliding contact switch attached to the manual shift shaft inside the transmission case. The Park/Neutral Position (PNP) Switch is integrated into the IMS and connects to the Transmission Control Module (TCM) lead frame through a short wire harness. The 5 inputs to the TCM from the transmission manual shift shaft switch assembly indicate the transmission gear selector lever position. This information is used for engine start enabling, engine controls as well as determining the transmission shift patterns.
The state of each input is available for display on the scan tool. The five input parameters represented are Signal A, Signal B, Signal C, Signal P (Parity), and Signal N (Park/Neutral Start Signal). Park/Neutral Signal is sent from the Park/Neutral switch directly to the Engine Control Module (ECM) and is used for engine start enable. The Park/Neutral Signal circuit is not connected to the TCM internally; the circuit uses the TCM as a pass-through connector only. The Diagnostic Trouble Code (DTC) will be set when the ECM detects the Park/Neutral switch signal equals 12 V, High, when the IMS reports a Park/Neutral range.

OBDII Code P0852 GMC - Park/Neutral Position Switch Circuit High Voltage - AutoCodes.com — P0852 GMC Code - Park/Neutral Position Switch Circuit High Voltage

What does this mean?

What are the Possible Causes of the DTC P0852 GMC?

Faulty Transmission Internal Mode Switch (IMS)
Transmission Internal Mode Switch harness is open or shorted
Transmission Internal Mode Switch circuit poor electrical connection
Faulty Control Solenoid Valve Assembly
Faulty Engine Control Module (ECM)

How to Fix the DTC P0852 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 P0852 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 P0852 GMC code?

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Information for Specific GMC Models

P0852 2014 GMC Sierra — Park/Neutral Position Switch Circuit High Voltage
P0852 2015 GMC Sierra — Park/Neutral Position Switch Circuit High Voltage
P0852 2016 GMC Sierra — Park/Neutral Position Switch Circuit High Voltage
P0852 2017 GMC Sierra — Park/Neutral Position Switch Circuit High Voltage
P0852 2018 GMC Sierra — Park/Neutral Position Switch Circuit High Voltage

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.