Powertrain, generic (extended)

P2DA2 Gear Shift Control Module B Supply Voltage High

Check engine lightOn
EmissionsNot relevant
Drive cycleNot required
Limp modePossible

P2DA2 is the over-voltage counterpart of P2DA1: gear shift control module B, the second selector unit of a shift-by-wire system, sees a supply above its permitted maximum. No manufacturer documents P2DA2 publicly or names the limit. Excess voltage usually comes from the charging side – a failed alternator regulator or DC/DC converter, a 24 V jump start, a battery charger left connected during diagnosis – and only rarely from a short between the module feed and a higher-voltage circuit. To protect itself the module may stop accepting inputs. Allison's 6th-generation controls show that a second selector is handled as a unit of its own with separate codes, so a fault there need not disable the first one. Measure charging voltage before replacing anything.

Likely causes

Alternator regulator or DC/DC converter delivering too much voltage
Jump start with 24 V or charger connected during operation
Module feed shorted to a circuit with higher voltage
Voltage measurement inside module B faulty

Symptoms

  • Shifter warning in the instrument cluster
  • Second selector does not respond, main selector may still work
  • Further overvoltage codes in other modules, flickering lights

Repair estimate

DifficultyMediumDIY possible
Parts and labour€20–700
Time0.5–3 h

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

gear shift control module bwiring harness

Related codes

P2DA1P2DA3P273DP0563U0291

References: law.cornell.edu, static.nhtsa.gov.