Gear Shift Control Module Communication Circuit High
The P085C code indicates that the powertrain control module (PCM) has detected a high voltage condition in the communication circuit of the gear shift control module. This module is responsible for sending shift commands to the transmission. A high voltage signal can be caused by a short to power, a faulty module, or wiring issues, potentially leading to erratic shifting or transmission malfunction.
01. Most Common Causes
- Short to power in the communication circuit
- Faulty gear shift control module
- Damaged wiring or connectors
- Corroded terminals
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Transmission shifting erratically or stuck in gear
- Reduced fuel economy
- Transmission fails to shift
03. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm the code and check for additional codes.
Step 2: Visually inspect the wiring and connectors for damage, corrosion, or loose connections.
Step 3: Test the communication circuit voltage with a multimeter to identify a short to power.
Step 4: If wiring is intact, test the gear shift control module per manufacturer specifications.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended as it can cause unpredictable transmission behavior, potentially leading to a safety hazard.
How much does it cost to fix?▼
Diagnosis typically costs $50-$150. Repair costs vary; a new module can be $200-$500 plus labor.