AutoCodes – Cadillac – U1839 Cadillac

U1839 Cadillac Code - Auxiliary Transmission Fluid Pump Control Module Lost Communication With Engine Control Module

Quick Answer

The serial data circuit is the means by which the devices in the vehicle communicate with each other. Common causes include Faulty Engine Control Module (ECM), Engine Control Module harness is open or shorted, Engine Control Module 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: U1839 Cadillac indicates Auxiliary Transmission Fluid Pump Control Module Lost Communication With Engine Control Module.
Common causes: Common causes include Faulty Engine Control Module (ECM), Engine Control Module harness is open or shorted, Engine Control Module 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 442

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 Jun 07, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code U1839 Cadillac Description

The serial data circuit is the means by which the devices in the vehicle communicate with each other. Once the scan tool is connected to the serial data circuit through the Data Link Connector (DLC), the scan tool can be used to monitor each device for diagnostic purposes and to check for Diagnostic Trouble Code (DTC). When the vehicle is ON, each device communicating on the serial data circuit sends a state of health message to ensure that the device is operating properly. When a device stops communicating on the serial data circuit, for example, if the device loses power or ground, the state of health message it normally sends on the serial data circuit disappears. Other devices on the serial data circuit, which expect to receive that state of the health message, detect its absence; those devices in turn set a DTC associated with the loss of the state of health of the non-communicating device. A loss of serial data communications DTC does not represent a failure of the devices that contain the stored DTC. The DTC will set when a supervised periodic message that includes the transmitter device availability has not been received.

OBDII Code U1839 Cadillac - Auxiliary Transmission Fluid Pump Control Module Lost Communication With Engine Control Module - AutoCodes.com — U1839 Cadillac Code - Auxiliary Transmission Fluid Pump Control Module Lost Communication With Engine Control Module

What does this mean?

What are the Possible Causes of the DTC U1839 Cadillac?

Faulty Engine Control Module (ECM)
Engine Control Module harness is open or shorted
Engine Control Module circuit poor electrical connection

How to Fix the DTC U1839 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 is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the U1839 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 U1839 Cadillac Code

1. What are common symptoms of OBDII code U1839 in a Cadillac?

Common symptoms include transmission issues such as erratic shifting, loss of power, and potential stalling of the vehicle.

2. What causes the OBDII code U1839 in a Cadillac?

The code U1839 is typically triggered when there is a communication failure between the auxiliary transmission fluid pump control module and the engine control module.

3. How serious is the U1839 code in a Cadillac?

While the severity can vary, it is important to address this code promptly as it can lead to transmission problems and affect the overall performance and safety of the vehicle.

4. Can driving with the U1839 code in a Cadillac cause further damage?

Continued driving with the U1839 code may exacerbate transmission issues over time, potentially leading to more costly repairs if left unresolved.

5. How is the U1839 code diagnosed in a Cadillac?

Diagnosing the U1839 code typically involves using an OBDII scanner to retrieve the specific fault code and then conducting further testing to pinpoint the exact communication issue.

6. What are possible DIY repair tips for the U1839 code in a Cadillac?

For DIY enthusiasts, checking the wiring connections between the auxiliary transmission fluid pump control module and engine control module for any loose connections or damage could be a good starting point.

7. Is it recommended to reset the U1839 code in a Cadillac after repairs?

After addressing the communication issue and fixing any underlying problems, it is advisable to reset the code using an OBDII scanner to clear the error and monitor if it reoccurs.

8. Can a faulty auxiliary transmission fluid pump control module cause the U1839 code in a Cadillac?

Yes, a malfunctioning auxiliary transmission fluid pump control module can contribute to the U1839 code by disrupting communication with the engine control module.

9. What is the typical cost to repair the U1839 code in a Cadillac?

The cost of repairing the U1839 code can vary depending on the extent of the issue and whether professional diagnostics and replacement of components are needed, with potential costs ranging from a few hundred to over a thousand dollars.

10. How can a mechanic help resolve the U1839 code in a Cadillac?

A qualified mechanic can efficiently diagnose the U1839 code, identify the root cause of the communication problem, and perform the necessary repairs or replacements to restore proper functionality to the vehicle's transmission system.