What Does U1231 Mean?
Secondary or alternate communication error related to electric defrost system data on the SCP J1850 network. This code typically accompanies U1230 and indicates persistent or intermittent communication loss with defrost components.
Common Causes
35%
Intermittent connection at defrost module connector due to vibration or corrosion
30%
Defrost control module internal circuit failure or corrupted software
20%
SCP network wiring chafing or intermittent short to ground/power
15%
Low system voltage or battery issue causing module communication dropout
Diagnostic Steps
1
Step 1: Wiggle test all connectors to defrost module while monitoring scan tool for code setting
2
Step 2: Measure battery voltage and charging system output to rule out power supply issues
3
Step 3: Inspect SCP bus wiring routing for potential chafe points against metal body panels
4
Step 4: Monitor network communication with scan tool during vehicle operation over bumps to identify intermittent faults
5
Step 5: Replace defrost control module if all connections and wiring are verified intact
Estimated Repair Cost
$150 - $700
Parts + labor, varies by vehicle and location
Secondary or alternate communication error related to electric defrost system data on the SCP J1850 network. This code typically accompanies U1230 and indicates persistent or intermittent communication loss with defrost components.
The most common cause of U1231 (SCP (J1850) Invalid or Missing Data for Electric Defrost) is: Intermittent connection at defrost module connector due to vibration or corrosion
Typical repair costs for U1231 range from $150 to $700, depending on the vehicle, location, and whether you do it yourself or go to a shop.
No direct safety impact. May result in inoperative rear window defrost reducing rear visibility in inclement weather.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to U1231 to identify the root cause.
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Quick Info
Category
Network
System
Body Control/Communication Network
Difficulty
Type
Manufacturer
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