Powertrain, generic (extended)

P2E29 Drive Motor A Excitation Current Sensor Circuit Low Voltage

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2E29 reports that the signal voltage of the excitation current sensor of drive motor A has dropped below the band the controller accepts. The sensor sits in the excitation stage that feeds direct current to the rotor field coil of an electrically excited motor; TI names shunts with isolated amplifiers or isolated Hall-effect sensors for this job. A reading pinned low is an electrical fault: a short to ground, a lost sensor supply or reference, or a dead sensor. No manufacturer documents P2E29 publicly. Implausible but valid readings are P2E28, a high signal P2E2A, the general circuit fault P2E7B. Because the field current can no longer be measured, the controller will likely switch the field off, as TI recommends for faults, and drive torque from this motor is lost.

Likely causes

Sensor signal line shorted to ground
Sensor supply or reference voltage missing
Excitation current sensor or its isolated amplifier failed

Symptoms

  • Electric drive warning lamp on
  • Loss of drive power from motor A
  • Vehicle may not become ready to drive

Repair estimate

DifficultyShop_onlyWorkshop job
Parts and labour€200–4,000
Time1–6 h

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

Parts involved

drive motor a excitation current sensordrive motor a excitation circuithybrid control module

Related codes

P2E7BP2E28P2E2AP2E2B

References: ti.com, law.cornell.edu.