P0852 2011 Subaru Manual Transmission

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#1
My 2011 manual transmission Subaru Impreza Outback Sport is showing code P0852 with the "Check Engine" light and "No Traction Control" light on, while the "Cruise Control" light flashes. The car starts and runs fine, and I'm convinced that there is a simple resolution that I don't have to pay a diagnostic fee and labor to fix. Is anybody familiar with this situation or have suggestions for a solution please? Thanks!
 

nickb2

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#2
Hello Hannah S, I will attempt to guide you the best I can.

The obd2 code you thankfully provided us with indicates that you have a problem with your neutral switch. Specifics of this code are "neutral switch input circuit high" MT model.

So, that being said, you may need to get your car scanned anyway to get more specific. Because if the car is starting fine, then this code may only have been an intermittent and might only be a STORED code. I would erase that code, drive for a while, and see if that specific code comes back. If it does, you may have to probe the circuit. But we are not there yet. Just erase the code.

Now, as to your cruise light flashing and traction control. Those two should in principle not be related, unless there is a brake switch input circuit code there also. I will study the wiring, which BTW I will post here also, so you can see my train of thought. I hope you know how to use a DVM/multimeter.

You will need a high end scanner to get the cruise code and the traction control codes/s. If the cruise light is flashing, then you diffidently have a code/s stored there for sure. You will need a high end scanner as I wrote above to get the cruise cancel codes.

If both lights came on at same time, probably related to something like a brake/stop light switch or something similar that both systems use.

Easy check, have someone press the brake pedal, do brake light light up? If yes, than probe circuit from brake light switch, clutch switch to ecm for for proper contuinuity after checking switch operation using the same mode on multimeter in ohms. Both switches operate the same a house light switch, it is on, or off. Anything in between is suspect and should be replaced.

Here are those wiring's I talked about. You will notice both TC and Cruise system use the same input switches to function. There is also the neutral switch that is involved here also (P0852;)), as the micro controller for the cruise control needs that input also. These may be related. But to make sure, it will be cheaper and time cost benefit to you too, just pay the small fee to get it scanned by a pro with a good scanner, and then be on your way with all those codes in hand, study the wiring's I provided, I will help each step of the way. Screenshot (160).png Screenshot (162).png Screenshot (163).png Screenshot (164).png
 

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nickb2

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#4
Of particular note, both trac and cruise are controlled by the combination meter micro controller. All this is on a CAN bus line communication line. So the ECM also communicates with that controller via CAN bus line, hence setting a OBD2 code (p0852) which you probably got with a low end code reader walamart type deal. Those code readers WILL NOT read ABS,TCS,Cruise systems. But I strongly believe these are all related to that neutral switch circuit. But better safe than sorry, get it scanned before throwing parts at this car just to end up finding it's a cut wire or similar or just a blown fuse.;)

See snapshot below of trac system, notice same micro controller as for the cruise system. Screenshot (165).png
 
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nickb2

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#5
Since the car starts, we can definitly cancel out the clutch cancel switch, don't look there for no reason, it will be a waste of time. Focus on the brake switch and neutral switch MT model.

Here is where to check that neutral switch on a manual. The brake switch is obviously on the brake pedal brakcet bolted to firewall inside the car, you may need to sprain your back a bit to get to it with your multimeter.:eek: Screenshot (166).png Screenshot (167).png