U1236 – SCP (J1850) Invalid or Missing Data for Memory Storage

The ODBII code U1236 indicates that there is invalid or missing data related to memory storage in the vehicle’s communication network, specifically using the SCP (J1850) protocol.

The severity of ODBII code U1236 is moderate.

Common Causes For: U1235 U1235: “Control Module Communication Failure”

• Faulty or damaged wiring/connectors
• Malfunctioning control modules
• Poor ground connections
• Corrupted data in the communication network
• Interference from aftermarket devices
• Software issues or bugs in the control module
• Low battery voltage or power supply issues
• Faulty sensors or actuators on the network

Common misdiagnosis for U1236 SCP (J1850) Invalid or Missing Data for Memory Storage

• Faulty OBDII connector
• Bad ground connections
• Malfunctioning PCM (Powertrain Control Module)
• Corrupted software or firmware in the PCM
• Wiring issues or shorts in the data bus
• Faulty sensors or actuators
• Issues with the vehicle’s battery or charging system
• Intermittent communication problems with other modules

Common Troubleshooting Steps

When dealing with OBD-II code U1236, which indicates “SCP (J1850) Invalid or Missing Data for Memory Storage,” there are several common troubleshooting steps you can follow to diagnose and potentially resolve the issue. Here’s a structured approach:

• Check for Other Codes: Use an OBD-II scanner to check for any additional trouble codes. Sometimes, related codes can provide more context for the issue.
• Inspect the Vehicle’s Battery and Charging System: Ensure the battery is fully charged and in good condition. A weak battery can cause communication issues.
• Check the alternator and charging system to ensure they are functioning properly.
• Examine the Wiring and Connectors: Inspect the wiring harness and connectors related to the SCP (J1850) communication line. Look for signs of damage, corrosion, or loose connections.
• Pay special attention to the connectors at the PCM (Powertrain Control Module) and any other modules that communicate over the SCP bus.
• Check for Ground Issues: Ensure that all ground connections are secure and free of corrosion. Poor grounding can lead to communication problems.
• Test the SCP Communication Line: Use a multimeter or oscilloscope to check the voltage levels on the SCP communication line. Compare the readings to the specifications in the vehicle’s service manual.
• Look for any short circuits or open circuits in the communication line.
• Inspect Modules for Faults: If the issue persists, check the modules that communicate over the SCP bus. This may include the PCM, ABS module, or other related control modules.
• If possible, perform a module reset or reprogramming if the manufacturer provides such procedures.
• Perform a Network Test: Some advanced scan tools can perform a network test to check the integrity of the communication bus. This can help identify if a specific module is causing the issue.
• Check for Software Updates: Verify if there are any software updates available for the vehicle’s modules. Sometimes, manufacturers release updates to fix known communication issues.
• 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 U1236 code for your specific vehicle make and model. Manufacturers may have documented fixes for known issues.1
• Seek Professional Help: If you are unable to resolve the issue after these steps, it may be necessary to consult a professional mechanic or technician who has experience with OBD-II systems and the specific vehicle in question. By following these steps, you should be able to identify and address the underlying cause of the U1236 code.