P090A

Code

Generic P — Powertrain

Clutch B Actuator Control Circuit/Open

Brand: Generic

Type: P — Powertrain

Views: UK: 31 EN: 87 RU: 42

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Page language: EN

Causes

Open or broken wiring between TCM and Clutch B actuator
Disconnected, corroded, or damaged connector/pins at actuator or TCM
Failed Clutch B actuator/solenoid (open coil)
Blown fuse or faulty relay supplying the actuator circuit
Internal driver failure in TCM/TCU
Water intrusion or corrosion in harness/connector

Symptoms

Transmission fault/wrench or check engine light illuminated
Certain gears may not engage or vehicle stuck in limp/low gear
Harsh, delayed, or no shifts related to Clutch B function
Poor drivability or loss of drive under load
Stored transmission-related DTCs and freeze-frame data

What to check

Read and record all transmission DTCs and freeze‑frame data with a scan tool
Visually inspect actuator connector and wiring for corrosion, damage, or water ingress
Check related fuses and relays for continuity and proper operation
Backprobe actuator connector and check for supply voltage and ground while commanding clutch
Measure actuator coil resistance with meter; check for open circuit
Perform continuity check from TCM pin to actuator pin (with ignition off)

Signal parameters

Supply voltage: battery voltage (~11–14 V) present at actuator supply pin with ignition ON (may be switched fused feed)
Control signal: TCM typically modulates ground or PWM (0–12 V range) when commanding actuator — behavior varies by design
Expected actuator coil resistance: typically low ohms (example ~6–30 Ω); open = infinite Ω (varies by vehicle)
Ground continuity: near 0 Ω from actuator ground to vehicle chassis ground; open if very high/OL
An open/high resistance condition often shows no voltage change or no current when commanded

Diagnostic algorithm

Verify code and record freeze frame and related codes (other clutch/solenoid/TCM codes).
Inspect connector and harness at Clutch B actuator for corrosion, bent pins, water, or mechanical damage. Repair as needed.
Check fuses/relays for the transmission actuator circuit; replace if blown or faulty.
With ignition OFF, disconnect actuator connector and measure coil resistance across actuator terminals. If infinite/OL, actuator is likely failed.
With connector connected, backprobe supply and control pins. With ignition ON, verify supply voltage present. With scanner, command Clutch B and observe control signal (voltage/PWM) and current draw.
If supply is present but no control signal, check continuity from TCM output pin to actuator control pin. Repair any open or shorted wiring.
If wiring and supply are good but actuator does not respond and coil resistance is within spec, suspect TCM output driver failure; confirm by commanding another known-good actuator (if available) or checking TCM outputs per manufacturer procedure.
Repair or replace faulty wiring, connector, fuse/relay, actuator, or TCM as indicated. Clear codes and test drive to verify repair.

Likely causes

Damaged/disconnected connector at the actuator (most common)
Broken wire or chafed harness to the actuator
Failed actuator coil (open circuit)
Blown fuse or failed relay supplying the actuator
Faulty TCM output driver (less common)

Fault status

⚠️ Status

Clutch B Actuator Control Circuit/Open — TCM detected open or very high resistance in the Clutch B actuator control circuit; clutch may not engage and transmission may enter limp mode.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours