U0199

Code

Generic U — Network/User

Lost Communication With Door Control Module A

Brand: Generic

Type: U — Network/User

Views: UK: 38 EN: 128 RU: 57

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Physical damage or break in the door harness (commonly at door hinge/boot)
Corroded or loose connector at the door module or body harness
Blown fuse or missing power/ground to the door control module
Faulty door control module (internal electronics failure)
Short or open on the CAN bus (CAN High / CAN Low) or missing bus termination
Network wiring shorted to battery or ground, or high resistance in the CAN lines

Symptoms

DTC U0199 stored (Lost Communication With Door Control Module A)
One or more doors do not lock/unlock with key fob or door switches
Power windows, mirror adjustments, or interior lights behave intermittently or do not operate
Door ajar / status message missing or incorrect on dash
Other modules report additional U-codes related to missing door module
Chimes, courtesy lights, or alarm functions may not operate for that door

What to check

Use a scan tool to verify U0199 and check for additional U-codes; confirm if the door control module is listed on the network
Check battery voltage and main body/door fuses with key on and engine off
Visually inspect door module connector, pins, and door jamb harness for damage, corrosion, or water intrusion
Wiggle test wiring in the door hinge area while watching live data/messages for intermittent connection
Measure CAN bus voltages at a known-good location and at the door module connector (see signal parameters)
Check CAN bus termination resistance (~60 ohms across CANH and CANL for two 120-ohm terminators in parallel)

Signal parameters

High-speed CAN idle common-mode: about 2.5 V on both CANH and CANL
Dominant state: CANH ~3.5 V, CANL ~1.5 V (levels vary by vehicle)
Bus differential (CANH - CANL) ~0 V (recessive) to ~2.0 V (dominant); verify with oscilloscope if available
Termination: approx. 60 ohms measured across CANH and CANL at key network points (vehicle dependent)
Typical baud rates: commonly 500 kb/s or 250 kb/s on high-speed CAN — confirm vehicle specification
Power supply to module: battery voltage within ~0.5 V of vehicle battery on key-on; ground should be near 0 ohms to chassis

Diagnostic algorithm

Connect a scan tool and confirm U0199 and any related codes. Record freeze frame / live data and which modules see the door module.
Check battery voltage and body power fuses related to door electronics. Replace any blown fuses and re-test.
Visually inspect the door module connector and door jamb harness for damage, corrosion, or pin push-out. Repair or replace damaged connectors.
With ignition on, check presence of the door module on the network via scan tool. If not present, measure power and ground at the module connector.
Backprobe CANH and CANL at the module connector and at a known-good network node. Verify idle voltages and differential activity with a multimeter or oscilloscope.
If CAN signals are absent at the module but present elsewhere, trace wiring between the door module and the main harness (pay attention to the hinge/boot area). Repair any opens/shorts.
If CAN lines show unexpected voltages (short to Vbatt or ground), isolate and locate the short by disconnecting sections or modules until normal levels return.
Perform wiggle tests on the harness while monitoring communication to find intermittent faults. Repair broken conductors or replace the harness as needed.
If wiring and power/grounds are good but the module does not communicate, attempt module reset/reprogramming per manufacturer procedure. If still non-responsive, consider module replacement and programming.
After repairs, clear codes and perform functional checks of door functions and verify no reoccurrence of U0199.

Likely causes

Broken conductor in the door jamb harness from repeated door movement
Corrosion/poor pin contact at the door module connector allowing intermittent comms
Blown fuse supplying the door module (check fuses for body/door circuits)
Failed door control module due to water intrusion or electrical surge
CANH or CANL shorted to power or ground in a door wiring splice
Missing termination resistor or open termination causing bus reflections

Fault status

⚠️ Status

Lost Communication With Door Control Module A — no valid CAN messages received from the door control module. Module may be unpowered, disconnected, or the network has an open/short.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours