What Does U1247 Mean?
Secondary or repeated communication error for Primary ID data on the SCP J1850 network. This indicates ongoing or intermittent failure of a primary control module to maintain network presence.
Common Causes
30%
Intermittent power supply issue to primary control module causing repeated resets
25%
Intermittent SCP bus wiring fault causing periodic communication dropouts
20%
Primary control module (PCM or BCM) internal intermittent hardware failure
15%
Poor ground connection causing module to lose network communication intermittently
10%
Voltage fluctuations from failing battery or alternator affecting module stability
Diagnostic Steps
1
Step 1: Monitor system voltage during key cycles and engine operation to detect voltage drops or spikes
2
Step 2: Perform voltage drop testing on power and ground circuits to primary control modules
3
Step 3: Use oscilloscope to capture SCP bus communication during fault occurrence to identify dropout patterns
4
Step 4: Wiggle test harnesses and connectors while monitoring network communication in real-time
5
Step 5: Load test battery and charging system to rule out electrical supply issues
Estimated Repair Cost
$180 - $1,100
Parts + labor, varies by vehicle and location
Secondary or repeated communication error for Primary ID data on the SCP J1850 network. This indicates ongoing or intermittent failure of a primary control module to maintain network presence.
The most common cause of U1247 (SCP (J1850) Invalid or Missing Data for Primary Id) is: Intermittent power supply issue to primary control module causing repeated resets
Typical repair costs for U1247 range from $180 to $1,100, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Intermittent loss of control module communication may cause unpredictable vehicle behavior. Avoid extended driving until repaired.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to U1247 to identify the root cause.
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Quick Info
Category
Network
System
Network Communication / Primary Control Modules
Difficulty
Type
Manufacturer
Recommended Tools
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