SCP (J1850) Invalid or Missing Data for Mirrors
Your vehicle's communication network isn't receiving proper data from the mirror control system. Think of it like a phone call where one person stops talking—the other person knows something is wrong but doesn't know what.
The body control module monitors SCP (Standardized Corporate Protocol) J1850 bus messages for mirror position and control data. It expects valid data packets at regular intervals; missing or corrupted messages trigger this fault. The ECU validates message checksums and timing to ensure reliable mirror operation.
| Parameter | Normal Range | Fault Condition |
|---|---|---|
| SCP Bus Message Valid | Valid data received every 100-200ms | Missing or invalid data for >500ms |
| Mirror Module Response | ACK signal present with correct checksum | No response or corrupted checksum detected |
Code U1194 is a moderate fault. You can generally drive to a workshop, but avoid long trips or high-load driving (motorway, uphill towing) until it is diagnosed. If the code keeps returning after clearing, or if you notice the symptoms listed above worsening, do not delay professional diagnosis. Many moderate codes have multiple possible root causes — a mechanic with live OBD data can identify the exact fault more efficiently than part-by-part trial and error.
Once the fault is repaired, U1194 can be cleared using any OBD-II scanner. Connect the scanner, navigate to "Clear Codes" or "Erase DTCs," and confirm. The check engine light turns off immediately.
The code will return if the root cause was not actually fixed. The ECM re-detects the fault within 1–3 drive cycles and sets the code again.