What Does U1146 Mean?
The vehicle's network communication system is not receiving valid security-related data over the SCP (Standard Corporate Protocol) J1850 bus. This indicates a breakdown in communication between the security module and other control modules.
Common Causes
35%
Failed or corrupted anti-theft/security module (PATS, PAM, or theft deterrent module)
30%
Damaged or corroded SCP bus wiring/connectors between security module and network
20%
Poor ground connection at security module or PCM
10%
Failed instrument cluster or body control module affecting network communication
5%
Low battery voltage or charging system issues causing module malfunction
Diagnostic Steps
1
Step 1: Use scan tool to monitor live SCP bus communication and verify which module is not transmitting security data
2
Step 2: Check battery voltage (should be 12.4V+ key off, 13.5-14.5V running) and inspect all battery/ground connections
3
Step 3: Inspect security module connector for corrosion, bent pins, or moisture; check module ground circuit resistance (<0.5 ohms)
4
Step 4: Test SCP bus voltage on positive and negative lines at security module (should be 2.5-3.5V each with key on)
5
Step 5: If wiring/voltage is good, attempt security module reprogram/relearn procedure; replace module if unsuccessful
Estimated Repair Cost
$150 - $800
Parts + labor, varies by vehicle and location
The vehicle's network communication system is not receiving valid security-related data over the SCP (Standard Corporate Protocol) J1850 bus. This indicates a breakdown in communication between the security module and other control modules.
The most common cause of U1146 (SCP (J1850) Invalid or Missing Data for Vehicle Security) is: Failed or corrupted anti-theft/security module (PATS, PAM, or theft deterrent module)
Typical repair costs for U1146 range from $150 to $800, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle may experience no-start conditions or limited functionality. Security features like passive anti-theft may be disabled, increasing theft risk.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to U1146 to identify the root cause.
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Quick Info
Category
Network
System
Vehicle Security/Anti-theft Network Communication
Difficulty
Type
Manufacturer
Recommended Tools
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