AutoCodes – Generic – U1420

U1420 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 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.

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Code Popularity 24,787

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

What does this mean?

What are the Possible Causes of the DTC U1420?

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?

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 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 code?

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

Need Help with the Code?

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

Information for Specific Makes

U1420 Chrysler — Implausible Electronic Gear Select Signal Received
U1420 Dodge — Implausible Electronic Gear Select Signal Received
U1420 Jeep — Implausible Electronic Gear Select Signal Received
U1420 RAM — Implausible Electronic Gear Select Signal Received

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 Code

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

- Common symptoms include issues with shifting gears, difficulty engaging the transmission, and potential sporadic stalling of the vehicle.

2. What can cause the OBDII code U1420 to trigger?

- The code U1420 can be triggered by a faulty gear selector switch, wiring issues in the gear selector circuit, or a malfunction in the transmission control module.

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

- To diagnose the U1420 code, you can use a diagnostic scanner to retrieve the code, inspect the gear selector switch and its wiring for any damage, and perform a thorough examination of the transmission control module.

4. Can a DIYer repair the U1420 code issue?

- Depending on your skill level, you may be able to repair the U1420 code issue yourself by replacing the faulty gear selector switch or repairing any damaged wiring in the circuit. However, for more complex issues with the transmission control module, it's recommended to seek professional help.

5. Are there any simple repair tips for the U1420 code?

- One simple repair tip for the U1420 code is to check and ensure all connections related to the gear selector switch are secure and free from corrosion. Additionally, inspecting the wiring harness for any signs of wear or damage can also help resolve the issue.

6. Can driving with the U1420 code present cause further damage to the vehicle?

- Driving with the U1420 code present can potentially cause further damage to the transmission system if the underlying issue is not addressed promptly. It's recommended to address the code and have the necessary repairs done as soon as possible.

7. Is it safe to continue driving with the U1420 code illuminated?

- It is not recommended to continue driving with the U1420 code illuminated, as it indicates a potential issue with the electronic gear select signal. Continued driving may lead to transmission problems and safety hazards.

8. How much does it typically cost to repair the U1420 code?

- The cost to repair the U1420 code can vary depending on the root cause of the issue and labor rates in your area. Repairs may range from a simple switch replacement costing a couple of hundred dollars to more complex wiring or module repairs costing more.

9. Will resetting the trouble codes make the U1420 code disappear permanently?

- Resetting the trouble codes may temporarily clear the U1420 code, but if the underlying issue is not resolved, the code is likely to reappear. It's crucial to diagnose and address the root cause to prevent the code from recurring.

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

- The time it takes to repair the U1420 code can vary based on the complexity of the issue. Simple repairs like replacing a gear selector switch can be done in a few hours, while more involved repairs involving the transmission control module may take longer and require professional expertise.