P0B0D: Electric/Auxiliary Transmission Fluid Pump Motor Control Module
What to do
This is one of the few codes where the electronics really are the likely answer — but only after the pump's windings and supply have been measured and found good. Ask whether the module is separate from the pump on this model: often it is not, and the two quotes are the same part.
What this code means
The module that drives the auxiliary pump has reported an internal fault.
A three-phase motor cannot be run by a switch. It needs electronics that synthesise three alternating supplies and shift them in step with the rotor, which is why this small pump has a control module of its own rather than a relay. That module has an output stage, and output stages fail.
The corpus's standing advice is not to blame the module, and this is one of the places that advice is deliberately reversed. P0964 sets out the test: a module is genuinely at fault when its circuits are reporting faults and the motor's windings measure correctly. Here the reasoning is the same. If the pump's windings are in specification and its supply is sound, what is left is the thing driving them.
One practical note before that conclusion: on many designs the module is integrated with the pump and is not separately available, so "replace the module" and "replace the pump" turn out to be the same job. Ask which it is on this vehicle before comparing quotes.
Likely causes
Start here
- Faulty auxiliary transmission fluid pump · specialist
Less common
- Corroded or loose connector · easy
- Water ingress into connector · easy
- Low system voltage · moderate
Symptoms
Components involved
Information, not instruction
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Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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