P085F Moderate Generic / SAE

P085F: Up and Down Shift Switch Circuit Range/Performance

What to do

The gearbox is fine and will shift for itself as normal — what you lose is the ability to ask for a gear yourself.

Say whether anything has ever been spilled into the centre console, or whether the car has been washed with an open window. A drink into the console is a common cause, and mentioning it saves a lot of time.

If the car has paddles on the steering wheel, mention any other steering wheel controls that have stopped working — the horn, the audio buttons, the cruise switches. They share a single ribbon connector behind the wheel, and if several have failed together that is the part, not the paddles.

Say whether it fails always or occasionally. An intermittent fault points at a connector or that ribbon; a permanent one points at the switch itself.

What this code means

The switch by which the driver asks for a higher or lower gear is producing a combination the module cannot make sense of.

Range/performance on a switch means something quite specific, and it is not simply "the switch is broken". A switch is either made or not made; there is no drift to detect. So what the module is objecting to is a combination or a pattern:

Both directions asserted at once. Up and down together is physically impossible from one paddle set, so the module rejects the pair — and this is the commonest version.
A voltage between the defined states, because these switches are usually a resistor ladder on one or two wires rather than a wire per button. A worn contact or a damp connector puts the reading between two rungs, which is neither a request nor a rest.
A request that never releases, held for far longer than a human hand would.

Where it comes from is almost always the environment rather than the electronics. Paddles and a manual gate are in the two places a car most often gets liquid spilled into it, on the steering column and in the centre console. A drink into the console is a genuine, common and expensive cause, and it usually announces itself by taking several unrelated switches with it.

Steering wheel paddles add a second cause that nothing else on the car has. Their signals cross to the fixed part of the vehicle through the clockspring, a flat ribbon that winds and unwinds every time the wheel is turned. It has a finite life measured in turns, and when it fails it takes the paddles, the horn, the wheel controls and often an airbag circuit with it.

What the driver loses is only the manual override. The transmission still shifts perfectly by itself; the paddles or the gate simply stop being obeyed, sometimes intermittently — which is the more irritating version, because it works until it is needed on a hill.

Likely causes

Start here

Faulty manual shift switch · moderate
Corroded switch contacts · moderate
Liquid damage to a switch or connector · moderate

Less common

Faulty steering column clockspring · specialist
Corroded or loose connector · easy

Symptoms

Components involved

Information, not instruction

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Community experience

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