What Does P0903 Mean?
The TCM/PCM has detected that the clutch actuator circuit voltage is above the expected threshold. In automated manual transmission systems, this high voltage condition suggests a short to battery voltage in the actuator circuit, a stuck relay, or an internal failure within the clutch actuator causing excessive current draw feedback. This prevents proper clutch modulation.
Safety Warning
A high circuit condition may cause the clutch to remain engaged or disengage unpredictably, creating a serious safety hazard. Do not drive; tow to a qualified repair facility.
Common Causes
35%
Short to battery voltage in clutch actuator wiring harness
30%
Clutch actuator motor failure with internal short to power
20%
Failed TCM output driver stuck in high state
15%
Clutch actuator relay stuck closed or welded contacts
Diagnostic Steps
1
Step 1: With key on engine off, backprobe the clutch actuator signal wire at the TCM connector — voltage should be near 0V when actuator is not commanded; battery voltage present indicates a short to power.
2
Step 2: Disconnect the clutch actuator and recheck voltage on the TCM side of the harness — if voltage drops, the actuator has an internal short; if it remains high, the harness has a short to power.
3
Step 3: Inspect the wiring harness routing for chafing against metal edges, particularly near the transmission bell housing and firewall pass-through.
4
Step 4: Measure clutch actuator motor resistance — compare to manufacturer specification (typically 2-15 ohms); very low resistance indicates an internal short.
5
Step 5: If all wiring and actuator test normal, substitute a known-good TCM or perform TCM output driver test using manufacturer-specific diagnostic software.
Estimated Repair Cost
$200 - $1,500
Parts + labor, varies by vehicle and location
The TCM/PCM has detected that the clutch actuator circuit voltage is above the expected threshold. In automated manual transmission systems, this high voltage condition suggests a short to battery voltage in the actuator circuit, a stuck relay, or an internal failure within the clutch actuator causi...
The most common cause of P0903 (Clutch Actuator Circuit High) is: Short to battery voltage in clutch actuator wiring harness
Typical repair costs for P0903 range from $200 to $1,500, depending on the vehicle, location, and whether you do it yourself or go to a shop.
A high circuit condition may cause the clutch to remain engaged or disengage unpredictably, creating a serious safety hazard. Do not drive; tow to a qualified repair facility.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0903 to identify the root cause.
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Quick Info
Category
Powertrain
System
Automated Manual Transmission (Clutch Control)
Difficulty
Type
Generic (SAE)
Recommended Tools
OBD2 Scanner
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