U1101 - SCP (J1850) INVALID OR MISSING DATA FOR PRIMARY ID

The U1101 OBDII diagnostic code is a manufacturer-specific code that is stored when the PCM (Powertrain Control Module) loses communication with the primary control module for a determined system. In most cases, this code points to the TCM (Transmission Control Module).

The SCP stands for Standard Corporate Protocol, which is a communication protocol used by several vehicle manufacturers. The J1850 is the SAE standard that describes the SCP protocol. When a vehicle operates, the control modules communicate with each other via the Controller Area Network (CAN). When sending data, each module sends its unique identification code along with the information it sends. The identification code shows the source of the data transmission.

• Check Engine light ON.
• The ABS, traction control, and stability control lights turn on.
• Stored multiple fault codes.
• Locking the transmission in a gear.
• The transmission does not select any gear.

Reasons for setting the U1101 OBD2 fault code:

• The circuit may have damage to its wires or connectors.
• A fuse or fuse link may be blown.
• The PCM or TCM could have a programming error or have defects.

To troubleshoot the U1101 OBDII DTC, follow these steps:

• First, please consult the Technical Service Bulletins.
• Consult a reliable vehicle information source for the locations of wires, connectors, and other electrical circuit components related to this code. If any of these show damage such as wear, corrosion, or burns, make corrections as necessary.
• Perform electrical checks on the wiring to verify continuity. If this value is inconsistent, make the appropriate repairs.
• If after performing the above-mentioned repairs you still get the U1101 code, a programming error has likely occurred in the modules involved. In this case, contact a specialized service center.