What Does U1199 Mean?
Secondary or duplicate external access communication fault on the SCP network. This indicates an additional door access module or sensor has lost network communication capability.
Common Causes
35%
Failed rear or passenger door module handling external access functions
30%
Damaged wiring to rear door handles or keypad entry system
20%
Body Control Module or secondary access controller failure
15%
SCP network bus degradation affecting multiple access control points
Diagnostic Steps
1
Step 1: Identify specific door or access point that has lost communication using scan tool module status
2
Step 2: Inspect and test rear door or secondary access point wiring and connectors
3
Step 3: Verify power and ground circuits to affected module or keypad assembly
4
Step 4: Check SCP bus signal presence and quality at the non-communicating module location
5
Step 5: Replace affected module if all circuit tests confirm proper voltage and bus signals
Estimated Repair Cost
$200 - $700
Parts + labor, varies by vehicle and location
Secondary or duplicate external access communication fault on the SCP network. This indicates an additional door access module or sensor has lost network communication capability.
The most common cause of U1199 (SCP (J1850) Invalid or Missing Data for External Access (Doors)) is: Failed rear or passenger door module handling external access functions
Typical repair costs for U1199 range from $200 to $700, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Rear door access or secondary entry points may not function properly. Could prevent emergency access or exit through affected doors.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to U1199 to identify the root cause.
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Quick Info
Category
Network
System
Body Control Network / Keyless Entry System
Difficulty
Type
Manufacturer
Recommended Tools
OBD2 Scanner
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