AutoCodes – Cadillac – U1255 Cadillac

U1255 Cadillac Code - Lost Communications

Quick Answer

Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Common causes include Loose control module connectors, Faulty control module, Control modules poor lectrical 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: U1255 Cadillac indicates Lost Communications.
Common causes: Common causes include Loose control module connectors, Faulty control module, Control modules poor lectrical 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 22,026

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 05, 2020

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code U1255 Cadillac Description

Modules connected to the class 2 serial data circuit monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. When a module receives a message for a critical operating parameter, the module records the identification number of the module which sent the message. These node alive messages are used for State of Health monitoring. A critical operating parameter is one which, when not received, requires that the module use a default value for that parameter. When a module does not associate an identification number with at least one critical parameter within 5 seconds of beginning serial data communication, DTC U1000 or U1255 is set. When more than one critical parameter does not have an identification number associated with it, the DTC will only be reported once. The following modules communicate on the class 2 serial data circuit:
- Audio amplifier
- Cellular telephone module w/UV8
- Dash integration module (DIM)
- Digital radio receiver
- Driver door module (DDM)
- Driver door switch assembly (DDSA)
- Electronic brake control module (EBCM)
- Electronic suspension control module (ESC)
- Front passenger door module (FPDM)
- Inflatable restraint sensing and diagnostic module (SDM)

OBDII Code U1255 Cadillac - Lost Communications - AutoCodes.com — U1255 Cadillac Code - Lost Communications

What does this mean?

What are the Possible Causes of the DTC U1255 Cadillac?

Loose control module connectors
Faulty control module
Control modules poor lectrical connection
Control Modules harness open or shorted

How to Fix the DTC U1255 Cadillac?

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

The code is set when the Powertrain Control Module (PCM) does not receive a message that it was expecting from another control module (e.g. Transmission Control Module, ABS Module), and does not know which control module did not send the message.

As with all loss of communication concerns, inspect the power, ground, and serial data circuits to the suspect module prior to replacing any parts.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the U1255 Cadillac 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.

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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 U1255 Cadillac Code

1. What does the OBDII code U1255 mean on a Cadillac?

U1255 indicates a "Lost Communications" issue, meaning one or more modules in the vehicle are unable to communicate via the data network.

2. What are common symptoms of the U1255 code on a Cadillac?

Symptoms may include warning lights on the dashboard, malfunctioning electronic systems, or intermittent performance issues.

3. What causes the U1255 code to trigger?

This code is typically caused by wiring issues, a faulty module, loose connections, or network interference in the vehicle's communication system.

4. Can a weak battery cause the U1255 code?

Yes, a weak or failing battery can cause communication errors, including the U1255 code.

5. How do I diagnose the U1255 code on my Cadillac?

Start by scanning for additional codes, inspecting wiring and connections, and testing the modules for proper functionality.

6. Can I still drive my Cadillac with the U1255 code?

It depends on the severity of the issue. If critical systems are affected, it may not be safe to drive. Have it inspected as soon as possible.

7. How can I fix the U1255 code on my Cadillac?

Repairs may involve cleaning or tightening connections, repairing damaged wiring, or replacing a faulty module.

8. Does the U1255 code always require module replacement?

No, module replacement is not always necessary. Often, the issue can be resolved by addressing wiring or connection problems.

9. Will clearing the U1255 code solve the problem?

Clearing the code without addressing the underlying issue will not fix the problem, and the code will likely return.

10. How much does it cost to repair the U1255 code on a Cadillac?

Repair costs vary depending on the root cause. Simple fixes like repairing wiring may cost less, while module replacement can be more expensive.

Discuss the causes and fixes for U1255 Cadillac OBDII Code

Submit a New Comment

Orlando
Date: August 24, 2015 at 7:44 pm

My car wont start. I have a 1998 cadillac seville sls and I recently installed a compressor a week ago. Now the lights work but it wont start. I just change out the battery and still the same problem .

Reply to Comment
OBDIITech
Date: August 26, 2015 at 1:07 am

Unfortunately there is not an easy code to diagnose code. The problem is that there is no communication between control modules of your vehicle, but detecting the defective module requires special tools and methods. I recommend having an experienced technician diagnose the problem.

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