What Does U1174 Mean?
The vehicle's communication network (SCP/J1850) is not receiving valid data from a specific module with a Primary ID. This indicates a module on the network is either not transmitting properly or its message format is corrupted.
Common Causes
35%
Faulty or failing body control module (BCM) or powertrain control module (PCM)
30%
Damaged or corroded wiring in the SCP data bus circuit
20%
Poor ground connection at network modules
10%
Low battery voltage or weak battery affecting module communication
5%
Module software corruption requiring reprogramming
Diagnostic Steps
1
Step 1: Check battery voltage and charging system; ensure voltage is above 12.4V with engine off and 13.5-14.5V running
2
Step 2: Inspect all network module connectors for corrosion, bent pins, or water intrusion
3
Step 3: Use scan tool to identify which module has the Primary ID referenced and check for communication loss
4
Step 4: Test SCP bus circuits for continuity, shorts to ground, and proper termination resistance (approximately 100-120 ohms)
5
Step 5: Verify all module ground connections are clean and tight with less than 0.1V drop
Estimated Repair Cost
$100 - $800
Parts + labor, varies by vehicle and location
The vehicle's communication network (SCP/J1850) is not receiving valid data from a specific module with a Primary ID. This indicates a module on the network is either not transmitting properly or its message format is corrupted.
The most common cause of U1174 (SCP (J1850) Invalid or Missing Data for Primary Id) is: Faulty or failing body control module (BCM) or powertrain control module (PCM)
Typical repair costs for U1174 range from $100 to $800, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle may experience intermittent loss of functions or fail to start. Generally safe to drive but may strand driver if communication loss worsens.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to U1174 to identify the root cause.
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Quick Info
Category
Network
System
Vehicle Communication Network
Difficulty
Type
Manufacturer
Recommended Tools
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