AutoCodes – Generic – P1684

P1684 Code - Battery Power To Module Disconnected

Quick Answer

The Diagnostic Trouble Code (DTC) P1684 will set when the Transmission Control Module (TCM) is disconnected from battery voltage or ground. Common causes include Battery was recently disconnected, Low battery voltage, Malfunctioning charging system. 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: P1684 indicates Battery Power To Module Disconnected.
Common causes: Common causes include Battery was recently disconnected, Low battery voltage, Malfunctioning charging system.
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.

Save to My Repairs My Repairs

AI answers can be wrong. Verify repairs with testing. Open full chat

Code Popularity 27,685

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 Jul 06, 2020

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
Comments
Add Comment

💬 Need more help? Ask Coddy for instant answers — it's free!

Code P1684 Description

The Diagnostic Trouble Code (DTC) P1684 will set when the Transmission Control Module (TCM) is disconnected from battery voltage or ground. The DTC data will be lost. The vehicle will go into immediate limp-in mode if power is lost while operating the vehicle. Normal operation is resumed if the power is restored during the same key start.

OBDII Code P1684 - Battery Power To Module Disconnected - AutoCodes.com — P1684 Code - Battery Power To Module Disconnected

What does this mean?

What are the Possible Causes of the DTC P1684?

Battery was recently disconnected
Low battery voltage
Malfunctioning charging system
Transmission Control Module (TCM) was replaced or disconnected
Faulty Transmission Control Module (TCM)
Transmission Control Module (TCM) harness is open or shorted
Transmission Control Module (TCM) circuit poor electrical connection

How to Fix the DTC P1684?

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 does this mean?

Code Tech Notes

If other codes are present, check and repair other codes first. Make sure the battery charge is OK and the battery connectors are firmly secure.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1684 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 P1684 code?

Need more information on how to fix the P1684 code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the P1684 code diagnosed by a professional: Find a repair shop in your area

Information for Specific Makes

P1684 Acura — Throttle Valve Return Spring Performance Problem
P1684 Buick — Transmission Control Module Power Up Temperature Sensor Performance
P1684 Cadillac — Transmission Control Module Power Up Temperature Sensor Performance
P1684 Chevrolet — Transmission Control Module Power Up Temperature Sensor Performance
P1684 Chrysler — Battery Power To Module Disconnected
P1684 Dodge — Battery Power To Module Disconnected
P1684 GMC — Transmission Control Module Power Up Temperature Sensor Performance
P1684 Honda — Throttle Valve Return Spring Performance Problem
P1684 Jeep — Battery Power To Module Disconnected
P1684 Pontiac — Transmission Control Module Power Up Temperature Sensor Performance
P1684 Saturn — Transmission Control Module Power Up Temperature Sensor Performance

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.