SPN 1705 FMI 6: Meaning and Fix
SPN 1705 FMI 6 indicates the Forward View Imager System detected a current above normal or a grounded circuit. This fault commonly appears after a collision repair or windshield replacement where the camera harness is pinched or not properly routed. Technicians frequently encounter this when the imager connector is contaminated with moisture or debris, causing a direct short to chassis ground.
Common Symptoms
- ADAS Disabled: Lane departure warning and collision mitigation systems are deactivated by the ECM.
- Dash Warning Light: Amber or red forward-imager fault lamp illuminates on the instrument cluster.
- No Camera Feed: Diagnostic tool reports no valid video data from the forward-facing imager module.
- Intermittent Shutdown: System randomly cuts out, especially during vibration or temperature changes.
Probable Causes
- Harness Short: Imager power or ground wire chafed against chassis metal, causing a direct short.
- Connector Corrosion: Moisture ingress at the 6-pin imager connector creates a low-resistance path to ground.
- Camera Module Failure: Internal short circuit within the imager’s power regulation stage due to component breakdown.
- ECM Driver Fault: ECM internal high-side driver for imager power supply failed shorted.
Advanced Technical Analysis
The ECM monitors the imager module’s supply current via a precision shunt resistor. If the current exceeds a calibrated threshold (typically 2.5 A) for more than 200 ms, the ECM sets FMI 6. This real-time current sensing prevents damage to the ECM’s internal driver and the imager’s sensitive CMOS sensor array.
A grounded circuit condition is often intermittent due to vibration. The ECM employs a debouncing timer of 500 ms to confirm the fault before logging. During this window, the imager voltage may drop below 9 V, causing corrupted pixel data and false object detections before the fault is latched.
Once the fault is active, the ECM de-energizes the imager power supply and disables all ADAS functions. A torque derate of 25% is applied in some OEM calibrations to limit vehicle speed in reduced-visibility conditions. The system will not recover until the fault is cleared and ignition is cycled.
Long-term prevention includes dielectric grease on connectors and ensuring the imager bracket is not over-tightened, which can crack the housing. In workshops, this fault frequently follows a windshield replacement where the camera was not recalibrated, causing the harness to be stretched and eventually short against the roof metal.
Step-by-Step Troubleshooting Guide
- Visual Inspection: Check imager connector and harness for pinch points, corrosion, or exposed wires near the windshield.
- Measure Resistance: Disconnect imager and ECM; measure resistance between imager power pin and chassis ground. Must be >100 kΩ.
- Isolate Supply: With ignition ON, measure voltage at imager connector. If 0V with fuse good, suspect ECM driver failure.
- Replace Module: If harness and ECM check OK, replace forward imager camera module and perform dynamic calibration.