P2DA2

Code

Generic P — Powertrain

Gear Shift Control Module B Supply Voltage High

Brand: Generic

Type: P — Powertrain

Views: UK: 20 EN: 30 RU: 20

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Battery/charging system producing excessive voltage (faulty alternator/regulator or aftermarket charger)
Short to battery or ignition voltage on the module supply circuit
Open/incorrect reference to ground causing a false high reading
Damaged wiring or corroded/loose connector pins creating intermittent/high resistance
Failed Gear Shift Control Module B internal regulator or sensor
Software/firmware error or incorrect configuration

Symptoms

DTC P2DA2 stored and possibly MIL/shift lamp illuminated
Erratic or unavailable gear shift control or limp shift mode
Intermittent loss of module communication on the data bus (CAN)
Vehicle may show other electrical anomalies or voltage-related codes
Possible inability to shift smoothly or storage of multiple transmission-related codes

What to check

Retrieve all stored codes and freeze frame data; note any accompanying transmission or charging-system codes
Visually inspect wiring harness and connector for Gear Shift Control Module B for damage, corrosion, or water
Measure battery voltage with key off and key on (engine off) using a DMM
Measure the module supply pin voltage with key on (and engine running) and compare to battery/charging voltage
Perform a voltage drop test and continuity check between battery positive and the module supply terminal
Check grounds associated with the module for tightness and corrosion; measure ground resistance to battery negative

Signal parameters

Battery voltage (static, key off): ~12.2–12.8 V (nominal)
Supply voltage at module, key on, engine off: should match battery within ~0.1–0.5 V
Charging system voltage, engine running: typically ~13.5–14.8 V (varies by vehicle)
High-voltage threshold that can set the code: often >15.5–16.5 V (manufacturer-specific)
Voltage spikes/transients: short-duration spikes can exceed 40 V — use scope to capture
Communications: CAN bus present/active and module addresses responding on scan tool

Diagnostic algorithm

Read and record trouble codes, freeze frame and any related codes (charging system, other shift modules).
Perform visual inspection of module B connector, wiring harness, and nearby components for damage, corrosion, or water ingress.
With a reliable DMM measure battery voltage (key off) and then measure the supply pin at Gear Shift Control Module B with key on, engine off. Compare values.
Start engine and measure charging voltage at battery and at the module supply pin. Note if voltage exceeds normal charging range.
If voltage is high, isolate source: disconnect loads/aftermarket chargers, remove accessory connections, and retest to see if voltage returns to normal.
Check continuity from module supply pin to fuse/relay and to battery positive. Repair any short or direct feed to battery that bypasses regulation.
Inspect and test engine/chassis grounds related to the module; clean and tighten ground points as needed, then re-measure.
If intermittent spikes are suspected, monitor supply with an oscilloscope while exercising vehicle electrical loads to capture transients.
If wiring and system voltage are normal with module disconnected, consider module internal regulator failure—compare with known-good module if available.
Repair or replace damaged wiring, connectors, or module as indicated. Clear codes, perform relearn procedures if required, and road test. Re-scan to confirm the code does not return.
Safety note: when disconnecting modules or performing electrical work, follow vehicle manufacturer procedures to avoid causing further faults or airbag/system damage.

Likely causes

High battery/charging system voltage (overcharging alternator or voltage regulator failure)
Power feed wire to Gear Shift Control Module B shorted to constant battery voltage
Poor/choppy ground at module causing sensor/regulator misreading
Corroded terminal or water intrusion at module connector causing intermittent high readings
Failed internal supply regulator inside the module
Recent jump-start, charger connection, or aftermarket electrical accessory introduced voltage spikes

Fault status

⚠️ Status

High supply voltage detected at Gear Shift Control Module B supply circuit. Diagnostic code stored when module supply exceeds allowed threshold or reports an internal over-voltage condition.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours