U1858 Cadillac Code - Electronic Brake Control Module Lost Communication With Hybrid/EV Powertrain Control Module On Chassis Expansion CAN Bus
Quick Answer
The Drive Motor Control Modules and the Hybrid/EV Powertrain Control Module 1 are all internal to the Power Inverter Module. Common causes include Faulty Hybrid/EV Powertrain Control Module, Hybrid/EV Powertrain Control Module harness is open or shorted, Hybrid/EV Powertrain 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
- U1858 Cadillac indicates Electronic Brake Control Module Lost Communication With Hybrid/EV Powertrain Control Module On Chassis Expansion CAN Bus.
- Common causes
- Common causes include Faulty Hybrid/EV Powertrain Control Module, Hybrid/EV Powertrain Control Module harness is open or shorted, Hybrid/EV Powertrain 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.
Code U1858 Cadillac Description
Communication diagnostics for the serial data, including device power and ground as well as the wakeup circuits for Drive Motor Control Modules and the Hybrid/EV Powertrain Control Module 1 are all diagnosed from external sources only to the Power Inverter Module connector because any circuit fault condition within the Power Inverter Module will cause a complete replacement.
The Diagnostic Trouble Code (DTC) will set when a supervised periodic message that includes the transmitter device availability has not been received.
What are the Possible Causes of the DTC U1858 Cadillac?
- Faulty Hybrid/EV Powertrain Control Module
- Hybrid/EV Powertrain Control Module harness is open or shorted
- Hybrid/EV Powertrain Control Module circuit poor electrical connection
How to Fix the DTC U1858 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 U1858 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.
Need more information about the U1858 Cadillac code?
Need more information on how to fix the U1858 Cadillac code? Get Access to Factory Service Manuals
Need Help with the Code?
Get the U1858 Cadillac code diagnosed by a professional: Find a repair shop in your area
Frequently Asked Questions about U1858 Cadillac Code
What does the OBDII code U1858 mean for my Cadillac?
The U1858 code indicates a communication failure between the Electronic Brake Control Module (EBCM) and the Hybrid/EV Powertrain Control Module over the Chassis Expansion CAN Bus, which can affect brake system performance.
What symptoms might I experience if my vehicle has the U1858 code?
Common symptoms include warning lights on the dashboard, such as the ABS or brake warning light, potential loss of hybrid or electric vehicle functionality, and impaired braking performance in some cases.
What are the potential causes of the U1858 code?
Causes can include faulty wiring or connectors in the CAN Bus system, a malfunctioning EBCM or Powertrain Control Module, or issues with the vehicle's battery or power supply affecting communication.
How can I diagnose the U1858 code?
To diagnose the U1858 code, use an OBDII scanner to confirm the code and check for any additional codes. Inspect the wiring and connectors for damage and test the EBCM and Powertrain Control Module functionality.
What should I check first if I get the U1858 code?
Start by inspecting the wiring and connectors between the EBCM and the Powertrain Control Module for any signs of damage, corrosion, or loose connections.
Can I drive my Cadillac if the U1858 code is present?
It is not recommended to drive the vehicle with the U1858 code, as it may affect braking performance and overall safety, especially if the ABS system is compromised.
What repairs might be necessary to fix the U1858 code?
Repairs may involve repairing or replacing damaged wiring and connectors, reprogramming or replacing the EBCM or Powertrain Control Module, or addressing any underlying electrical issues.
Is it possible to clear the U1858 code without fixing the issue?
While you can clear the code with an OBDII scanner, it is crucial to address the underlying issue to prevent the code from returning and ensure safe vehicle operation.
How much might it cost to diagnose and repair the U1858 code?
Diagnosis costs can range from $100 to $200, while repairs can vary widely based on the specific issue identified, ranging from simple wiring repairs to more costly module replacements. Always consult with a professional mechanic for an accurate estimate.
Discuss the causes and fixes for U1858 Cadillac OBDII Code
Code U1858 Cadillac comments
No comments found for this page.
Fix Your Car Smarter
Try the New AutoCodes App!
Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.
