P0964: solenoid B open circuit is not a universal valve location

P0964 identifies pressure-control solenoid B control circuit open. The source explicitly assigns B differently across eight-, nine- and ten-speed clutch systems and uses it for the primary-pulley solenoid in the CVT example.

Establish the controlled circuit before the repair theory

The table's open-circuit criterion is a controller-specific voltage signature designed around more than 200 kilohms between signal and controller ground. It does not determine from the code alone whether the discontinuity is inside the solenoid, in its connection, or elsewhere in the controlled path.

Nor does this electrical code directly demonstrate low primary-pulley pressure or a failed clutch application. Those physical outcomes require separate observations appropriate to the actual transmission.

An enabled supply is part of the test

The monitor requires the solenoid's mapped high-side supply on, qualifying power mode and battery voltage above 9 but below 32 volts for more than one second. Failure must exceed 0.3 second within a sample period exceeding half a second.

Record the B mapping and supply state before judging an absent fault after clearing. A disabled supply or no-driver mapping can prevent evaluation rather than demonstrate a repair. Verification should establish a passing open-circuit monitor with the appropriate path active, then complete the vehicle's required operational checks. The source does not supply a safe forced-power test or a blanket instruction to replace a solenoid pack.

Source and applicability

Documented monitors in gm-2025-03a, model year 2025. These are module/calibration examples; vehicle, engine and transmission applicability must be confirmed independently. GM 2025-03a, page 1145.