P0931

Code

Generic P — Powertrain

Gear Shift Lock Solenoid/Actuator Control Circuit A High

Brand: Generic

Type: P — Powertrain

Views: UK: 35 EN: 60 RU: 32

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Page language: EN

Causes

Open or damaged wiring in the gear shift lock solenoid control circuit
Short to battery voltage on the solenoid control circuit
Corroded, bent or loose connector pins at the solenoid or PCM/TCM
Faulty gear shift lock solenoid/actuator (internal short or intermittent)
Faulty PCM/TCM driver or internal circuit fault
Aftermarket modifications or incorrect repairs causing wiring/connector damage

Symptoms

Gear shift lock may not release or may lock unexpectedly
Transmission may not shift into gear or displays refusal-to-shift symptoms
DTC P0931 stored, possibly with MIL on (depending on vehicle)
Intermittent shift lock operation or poor gear selection feel
Possible diagnostic trouble codes related to transmission control or solenoids

What to check

Retrieve freeze frame and fault history with a scan tool; note conditions when DTC set
Visually inspect wiring harness and connectors for chafe, corrosion, heat damage, or bent pins at solenoid and PCM/TCM
Check connector terminals for corrosion, pushed-out pins, or water intrusion
Measure voltage at the solenoid connector with key ON (compare to battery voltage)
Backprobe the control circuit at the PCM/TCM connector and at the solenoid to compare readings
Check solenoid coil resistance and compare to specification

Signal parameters

Inactive (no PCM command): circuit may sit near battery voltage through solenoid — approx 11–14 V (vehicle specific)
Active (PCM grounds low-side driver): voltage at solenoid/driver should be
Open-circuit voltage reading: near battery voltage at PCM pin with solenoid disconnected indicates open/short to B+ or high impedance
Solenoid coil resistance (typical range): 5–50 ohms (varies by model) — consult vehicle spec
If PCM driver is shorted to B+, voltage at PCM output may remain near battery voltage regardless of command

Diagnostic algorithm

Scan for codes, record freeze frame data and any related transmission codes. Clear codes and attempt to re-create condition.
Visually inspect connectors and wiring between the PCM/TCM and gear shift lock solenoid. Repair any damaged harness sections.
With connector disconnected, measure solenoid coil resistance. If infinite or significantly out of spec, replace solenoid.
Reconnect and backprobe solenoid control circuit. With ignition ON and PCM commanding OFF, verify approx battery voltage at solenoid feed. With PCM commanding ON, observe voltage drop to
If the circuit reads battery voltage when PCM should be driving low, check for short to B+ (inspect wiring for chafe to constant power). Repair short if found.
If wiring checks good and solenoid coil ok, test PCM output: command the solenoid on/off using a capable scan tool while monitoring voltage. If PCM output stays high and wiring/solenoid are good, suspect PCM/TCM driver failure — consult manufacturer repair/replace procedures.
After repairs, clear codes and perform functional test of gear shift lock; road test as required. Verify DTC does not return.
Safety note: disconnect battery before repairing connectors or wiring. Use manufacturer procedures when replacing PCM/TCM.

Likely causes

Broken/open wire between PCM and solenoid causing a floating/high reading
Wire shorted to battery positive (B+) due to chafing or pin contact
Corroded connector at the solenoid allowing intermittent high-voltage reading
Failed low-side driver inside PCM/TCM (stuck high)
Solenoid winding internally shorted to supply

Fault status

⚠️ Status

PCM detected high voltage on Gear Shift Lock Solenoid/Actuator Control Circuit A — circuit reading higher than expected; DTC P0931 set.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours

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