P0947

Hydraulic Pump Relay Circuit Low

Severity: High
Driving: Drive only to a garage

The hydraulic pump relay circuit is reading low - typically shorted to earth, or the relay not closing. The module cannot control the pump, so the transmission will either lose hydraulic pressure or keep the pump running when it should be off.

Possible causes

CommonWiring shorted to earth, or the relay not closing between the module and the relay
CommonFailed relay
CommonCorroded relay socket
PossibleWater ingress into the fuse box
RareFailed control module driver

What you might notice

Pump not running, or running continuously
Transmission will not change gear
Battery flat after standing
Check engine light on

What to check, in order

Check whether the low reading persists with the relay removed. That separates the relay from the wiring.
Swap the relay with an identical one and see whether the fault follows.
Inspect the socket for corrosion and heat damage.
Check the fuse box for water.
A pump running continuously will wear out and will flatten the battery. Do not leave the car standing with this fault.

Read this code from your own car

Plug an ELM327 adapter into the OBD-II port under the dashboard. Pin16 reads every stored, pending and permanent code, explains each one like this page does — offline, with no account — and shows what the car recorded when the fault was set.

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Where this code sits

B · Body C · Chassis P · Powertrain U · Network and communication

Transmission and control modules