Powertrain, generic (extended)

P281B Pressure Control Solenoid H Control Circuit/Open

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P281B stands for an open control circuit of solenoid H. GM's 2020 tables apply it to the converter clutch valve of nine- and ten-speed automatics and to the T93 eight-speed default valve; an impedance of about 200 kilohm, seen for 0.3 s of 0.5 s, sets a Type A fault in one trip. On the T87a eight-speed controllers an open default valve circuit is filed as P281D instead. In the 2023 Corvette dual-clutch box H is the redundant shutdown valve of the differential lock; with the output off, the driver tries to hold the pin low with a tiny current, and if it succeeds the load is missing, confirmed after 150 ms as Type B. Broken wires, a backed-out terminal or an open coil are the usual causes; converter lockup or the differential lock is then lost.

Likely causes

Open coil in solenoid H
Terminal pushed back or loose in the connector
Broken wire in the internal or external transmission harness

Symptoms

  • MIL on after one trip
  • No converter clutch lockup, higher engine speed at cruise
  • Limited-slip differential disabled (Corvette dual-clutch)

Repair estimate

DifficultyHardWorkshop job
Parts and labour€80–2,500
Time1–6 h

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

Parts involved

pressure control solenoid hwiring harness

Related codes

P281DP281EP2819P2812P2817

References: gsi.ext.gm.com, gsi.ext.gm.com, law.cornell.edu.