U1750 – SCP (J1850) Lack of Acknowledgment for Audible Warnings

The ODBII code U1750 SCP (J1850) indicates a communication issue where the system is not receiving an acknowledgment for audible warnings, suggesting a problem with the communication network or the components responsible for generating those warnings.

The severity of ODBII code U1750 SCP (J1850) Lack of Acknowledgment for Audible Warnings is typically considered moderate.

Common Causes For: U1749 U1749: Transmission Control Module Communication Error

• Faulty audio warning module
• Poor electrical connections or wiring issues
• Malfunctioning instrument cluster
• Software or firmware issues
• Faulty communication lines (SCP bus)
• Defective sensors related to audible warnings
• Grounding issues in the vehicle’s electrical system

Common misdiagnosis for U1750 SCP (J1850) Lack of Acknowledgment for Audible Warnings

• Faulty audio warning system
• Defective instrument cluster
• Malfunctioning body control module (BCM)
• Wiring issues or shorts in the communication network
• Incorrectly programmed or updated software
• Faulty sensors related to warning systems
• Battery or power supply issues affecting the system

Common Troubleshooting Steps

The OBD-II code U1750 indicates a communication issue related to the SCP (Serial Communication Protocol) on the J1850 bus, specifically concerning a lack of acknowledgment for audible warnings. Here are some common troubleshooting steps to diagnose and resolve this issue:

• Check for Other Codes: Start by scanning the vehicle for any additional trouble codes. Sometimes, related codes can provide more context for the issue.
• Inspect Wiring and Connectors:
• Check the wiring harness and connectors associated with the J1850 bus for any signs of damage, corrosion, or loose connections.
• Pay special attention to the connectors for the modules involved in the audible warning system.
• Verify Power and Ground:
• Ensure that the modules involved in the communication have proper power and ground connections. Use a multimeter to check voltage and ground continuity.
• Test the Modules:
• Identify the modules that communicate over the J1850 bus (e.g., the instrument cluster, body control module, etc.) and test them for proper operation.
• If possible, use a scan tool to check if the modules are responding correctly to commands.
• Check for Short Circuits:
• Inspect the wiring for any short circuits that could be affecting communication. This can include shorts to ground or to other circuits.
• Look for Interference:
• Ensure that there are no aftermarket devices or modifications that could be interfering with the communication on the J1850 bus.
• Perform a Network Test:
• Use a scan tool capable of performing a network test to check the communication between modules. This can help identify if a specific module is not responding.
• Clear Codes and Test Drive:
• After performing the above checks and repairs, clear the trouble codes and take the vehicle for a test drive to see if the code returns.
• Consult Technical Service Bulletins (TSBs):
• Check for any TSBs related to the specific make and model of the vehicle. Manufacturers may have issued guidance on common issues related to the U1750 code.
• Replace Faulty Components:
• If a specific module is identified as faulty during testing, consider replacing it. Ensure that any replacement parts are compatible with the vehicle. 1
• Seek Professional Help:
• If the issue persists after performing these steps, it may be necessary to consult a professional technician or a dealership for further diagnosis. By following these troubleshooting steps, you should be able to identify and resolve the issue related to the U1750 code.