Code
C1905
Other
C — Chassis
Ride Control LR Shock Actuator Circuit Failure
AI status
Completed
Completed
100%
Causes
- Open or shorted wiring between ride control module and LR shock actuator
- Corroded, loose, or damaged connector/pins at the LR actuator
- Failed LR shock actuator (internal electrical fault)
- Blown fuse or faulty relay supplying the ride control circuit
- Poor ground at actuator or module
- Faulty ride control / suspension control module or software fault
Symptoms
- Suspension adaptive damping disabled or stuck in a single mode
- Ride feels excessively soft, firm, or inconsistent at left rear
- Suspension warning light or CID message illuminated
- Uneven ride height or vehicle tilt under some conditions
- Diagnostic trouble code C1905 stored in ride control module
- Possible unusual noise from left‑rear shock area
What to check
- Retrieve stored codes and freeze‑frame data with a scan tool and record any related codes
- Perform a visual inspection of LR shock, connector, and wiring harness for damage, corrosion, or water ingress
- Check fuses and relays related to ride control/suspension
- Wiggle the LR connector and harness while monitoring for intermittent faults
- Inspect grounds for cleanliness, tightness and corrosion at the chassis and module
- Use a DVM or oscilloscope to backprobe connector while commanding actuator and observe voltage/waveform
Signal parameters
- Actuator power supply: typically key‑on battery voltage at fuse/relay feed (check spec)
- Control signal: often PWM or variable voltage from suspension control module — expected change when commanded (0–battery voltage range)
- Feedback signal (if present): position or current feedback may vary with damping command (refer to OEM values)
- Static resistance between actuator power and return when disconnected: low ohms for electromagnetic actuators (compare to spec)
- Look for intermittent dropouts or high resistance indicating corrosion/poor contact
Diagnostic algorithm
- Confirm C1905 and note any additional ride control or chassis codes
- Perform thorough visual inspection of LR shock, connector and wiring (look where harness flexes)
- Check related fuses/relays and restore if blown; retest for code return
- Backprobe LR actuator connector with a DVOM/oscilloscope while commanding different damping settings from a diagnostic tool; verify presence and change of control signal (voltage/PWM)
- If no control signal at connector, trace wiring to suspension control module: check continuity, shorts to ground/battery, and connector pin condition
- If control signal present at connector but actuator does not respond, measure actuator resistance and compare to OEM spec — if out of spec or open/short, replace actuator
- If actuator replacement is required, secure all harnesses, replace actuator, and verify connector seals and grommets
- If wiring is damaged, repair using correct automotive methods (splice, heat‑shrink, seal) and protect harness from chafing
- If wiring and actuator test good but fault persists, test or replace suspension control module or reflash software per OEM procedures
- Clear codes, perform self‑tests and a road/ride test to confirm fault does not return
Likely causes
- Disconnected or corroded connector at the left‑rear shock
- Wiring harness chafe or break near suspension components
- Internal failure of the LR shock actuator
- Blown fuse or power supply interruption to the actuator circuit
Fault status
Status
Ride Control Left‑Rear shock actuator circuit fault — electrical open/short or actuator failure detected.
Repair difficulty: Medium
Diagnostic time: 1.0-2.5 hours
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