Engine-Codes - Gmc - U1000 GMC

U1000 GMC - Invalid Or Missing Data for Primary Id

Repair Importance Level: 3/3
Repair Difficulty Level: 3/3  What is this?
Table of contents

U1000 GMC Possible Causes

  • Faulty Module that is not communicating
  • Module harness is open or shorted
  • Module circuit poor electrical connection

How is the U1000 GMC code repair?

Start by checking the "Possible Causes" listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector's pins.

Tech Notes

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 U1000 GMC code

Labor: 1.0

The cost to diagnose the U1000 GMC code is 1.0 hour of labor. The auto repair's diagnosis time and labor rates vary by location, vehicle's make and model, and even your engine type. Most auto repair shops charge between $75 and $150 per hour.
How much do you know about cars?

Take the AutoCodes.com automotive tests and turbo-charge your car repair knowledge

Play Now

When is the code detected?

U1000 is set when the control module does not receive a message that it was expecting from another control module, and does not know which control module did not send that message.

Possible Symptoms

  • Engine Light ON (or Service Engine Soon Warning Light)

U1000 GMC Meaning

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 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, Diagnostic Trouble Code (DTC) U1000 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 class 2 serial data line on this vehicle is a star configuration, with the Body Control Module (BCM) and Powertrain Control Module (PCM) each have a second class 2 serial data line between them. The following modules communicate on the class 2 serial data line:
- Audio amplifier
- Body control module (BCM)
- Cellular telephone module w/UV8
- Dash integration module (DIM)
- Digital Radio Receiver (DRR)
- Driver Door Module (DDM)
- Driver Seat Module (DSM)
- 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)
- HVAC control module
- Hybrid Control Module (HCM)
- Instrument Panel Cluster (IPC)
- Powertrain/Engine Control Module (PCM/ECM)
- Radio
- Rear Seat Audio (RSA) Controller
- Rear Seat Entertainment (RSE) Assembly
- Rear Wheel Steering Control Module (RWSCM)
- Remote playback device-CD player (CDX)
- Transfer case shift control module (TCSCM)
- Transmission control module (TCM)
- Vehicle communication interface module (VCIM)

More Information

Need more information on how to fix the U1000 GMC code?
Get Access to Factory Service Manuals

Need more help?

Get the U1000 Gmc code diagnosed by a professional: Find a repair shop in your area