Fix P0861: STEP-BY-STEP diagnostic GUIDE!

The P0861: Gear Shift Module Communication Circuit Low refers to an issue where the communication circuit between the gear shift module and other vehicle systems is detecting lower-than-expected voltage. This can lead to transmission malfunctions or improper shifting. The problem could arise from faulty wiring, a malfunctioning gear shift module, or transmission control module (TCM) issues.

P0861 – Quick Overview

CodeInformation
MeaningP0861: Gear Shift Module Communication Circuit Low
Is it serious?Yes, this can cause improper gear shifting and transmission issues.
Possible causes– Low voltage in the gear shift module communication circuit
– Faulty module or wiring
– Faulty transmission control module (TCM)
How to diagnose?– Test the circuit for low voltage
– Inspect wiring and connectors
– Replace faulty components if needed

P0861 Meaning

The P0861: Gear Shift Module Communication Circuit Low code indicates that the voltage in the communication circuit between the gear shift module and the vehicle’s control systems is below the expected range. This can result in improper communication, which may cause the transmission to malfunction, preventing proper shifting.

Step-by-step diagnostic guide

ActionDescriptionTools Needed
Check for Other CodesUse an OBD-II scanner to check for additional communication-related or transmission codes.OBD-II Scanner
Inspect Gear Shift ModuleVisually inspect the gear shift module for any signs of damage, wear, or loose connections.Flashlight, Safety Gloves
Test the Circuit for Low VoltageUse a multimeter to measure the voltage in the gear shift module communication circuit and ensure it falls within manufacturer specifications.Multimeter
Check Wiring and ConnectorsInspect the wiring and connectors for damage, corrosion, or loose connections that could cause low voltage in the circuit.Flashlight, Multimeter
Replace Faulty ComponentsIf the gear shift module, wiring, or connectors are faulty, replace the necessary components to restore proper communication voltage.Replacement Parts, Basic Tools
Clear the Code and Test DriveAfter repairs, clear the code using an OBD-II scanner and take the vehicle for a test drive to ensure proper transmission function.OBD-II Scanner, Vehicle Owner’s Manual
Recheck for CodesAfter the test drive, re-scan the system to confirm that the P0861 code does not return.OBD-II Scanner
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