Powertrain, generic · Transmission

P0948 Hydraulic Pump Relay/Control Circuit High

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

The control line of the hydraulic pump relay or driver shows a higher voltage than expected, typically because it is shorted to battery voltage or the relay coil is open on a low-side driver. The pump then cannot be switched on, or the module sees it as active when it is not. J2012 places this code with the pump control circuit; Ferrari however reads P0948 on its DCT as no signal from the system pressure output, an unrelated use. The pump and accumulator unit of an automated gearbox is described in a ZF patent. CARB requires circuit checks on transmission outputs. P0947 is the low counterpart, P0945 the open fault and P0946 the plausibility fault. Expect a warning and possible loss of pump pressure.

Likely causes

Relay control wire shorted to battery voltage
Open relay coil seen as high level by the driver
Control module fault

Symptoms

  • Warning light on
  • Pump does not start
  • Gear changes not possible or stop-start disabled

Repair estimate

DifficultyMediumDIY possible
Parts and labour€30–500
Time0.5–3 h

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

Parts involved

hydraulic pump relaywiring harnesstcm

Related codes

P0945P0946P0947P094B

References: static.nhtsa.gov, patents.google.com, law.cornell.edu.