AutoCodes – RAM – U1420 RAM

U1420 RAM Code - Implausible Electronic Gear Select Signal Received

Quick Answer

This diagnostic checks for the validity and availability of the Shift Lever Position signal which is sent by the Electronic Shift Module (ESM) via a CAN message. Common causes include Faulty Electronic Shift Module (ESM), Electronic Shift Module (ESM) harness is open or shorted, Electronic Shift Module (ESM) 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: U1420 RAM indicates Implausible Electronic Gear Select Signal Received.
Common causes: Common causes include Faulty Electronic Shift Module (ESM), Electronic Shift Module (ESM) harness is open or shorted, Electronic Shift Module (ESM) 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.

Save to My Repairs My Repairs

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

Code Popularity 10,676

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 May 23, 2020

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

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

Code U1420 RAM Description

This diagnostic checks for the validity and availability of the Shift Lever Position signal which is sent by the Electronic Shift Module (ESM) via a CAN message. A CAN signal state is defined for each of five stable lever positions: 'Park', 'Reverse', 'Neutral', 'Drive' and 'Autostick'. CAN signal states are defined for six non-stable positions: 'Up', 'Down', 'P-R', 'R-N', 'N-D' and 'D-A'. The diagnostic checks the validity by verifying the received CAN signal state corresponds to one of the possible lever positions. The diagnostic also checks the availability by verifying the valid bit. When the Shift Lever Position signal is invalid or missing, then the Diagnostic Trouble Code (DTC) U1420 will set. The failure is detected if at least one of the following malfunctions is verified: 1) Signal Not Available Check: When the signal is not available, the ESM sends an SNA default value. If the TCM reads this value, then DTC U1420 is set. 2) Signal Invalid Value Check: If the signal value is equal to a different value than the defined values for the lever position, the Shift Lever Position value is considered not valid, then DTC U1420 is set.

OBDII Code U1420 RAM - Implausible Electronic Gear Select Signal Received - AutoCodes.com — U1420 RAM Code - Implausible Electronic Gear Select Signal Received

What does this mean?

What are the Possible Causes of the DTC U1420 RAM?

Faulty Electronic Shift Module (ESM)
Electronic Shift Module (ESM) harness is open or shorted
Electronic Shift Module (ESM) circuit poor electrical connection
Faulty Powertrain Control Module (PCM)
Faulty Transmission Control Module (TCM)

How to Fix the DTC U1420 RAM?

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 U1420 RAM 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 U1420 RAM code?

Need more information on how to fix the U1420 RAM code? Get Access to Factory Service Manuals

Need Help with the Code?

Get the U1420 RAM code diagnosed by a professional: Find a repair shop in your area

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.

Frequently Asked Questions about U1420 RAM Code

1. What are the common symptoms of OBDII code U1420 RAM?

- Common symptoms include issues with shifting gears, the transmission not engaging properly, and the transmission staying in one gear.

2. What could cause the OBDII code U1420 RAM to appear?

- The code may appear due to a faulty gear selector switch, wiring issues, a malfunctioning transmission control module (TCM), or a bad connection between components.

3. How can I diagnose the cause of the U1420 RAM code?

- Diagnosis typically involves checking the gear selector switch, inspecting the wiring for any damage, testing the TCM for proper function, and verifying connections between components.

4. Can I continue driving my vehicle with the U1420 RAM code present?

- It is not recommended to continue driving with the code present, as it can lead to further transmission issues and potential safety hazards. It's best to address the problem promptly.

5. What are some repair tips for fixing the U1420 RAM code?

- Repair tips include checking and repairing any damaged wiring, replacing the gear selector switch if faulty, reprogramming the TCM if needed, and ensuring all connections are secure.

6. Is the U1420 RAM code a serious issue?

- Yes, the U1420 RAM code is considered a serious issue as it can affect the proper functioning of the transmission, leading to potential safety risks and further damage if not addressed promptly.

7. How long does it typically take to repair the U1420 RAM code?

- The repair time can vary depending on the exact cause of the code, but it may take a few hours to a full day to diagnose and fix the issue properly.

8. Can I reset the U1420 RAM code myself?

- While you can clear the code with an OBDII scanner, it is important to address the underlying issue causing the code to prevent it from reoccurring.

9. Will the U1420 RAM code cause my vehicle to go into "limp mode"?

- In some cases, the U1420 RAM code can trigger the vehicle to go into "limp mode," limiting the transmission's functionality to prevent further damage.

10. How much does it cost to repair the U1420 RAM code?

- The cost of repairing the U1420 RAM code can vary depending on the extent of the issue, the necessary repairs or replacements, and labor costs at the service provider.