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07 2.5i wagon, bad brake switch and "OIL AT TEMP" light flashing


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#1 kero

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Posted 28 May 2011 - 01:09 AM

Hey,

I have done quite a bit of research on my two problems, will try to be brief but for me, it's hard, I have keyboard diarehea ROFL!

Please note that both issues started at the same time and both continue as of today.

Car: 07 2.5i wagon with 4eat, 42K, well maintained, complete UEL catless exhaust sytem, all other mods are suspension and appearance related.

#1 P0719 SUBARU - Torque Converter Brake Switch B Circuit Low:

After doing my homework, I'm gonna replace the brake switch, as of the past few days, the brake lights regardless of gear, only work when they feel like it. Most of the times, they don't work at all. Found this out fromt the wife when driving behind me from or to work, etc. So this seems to be the easy issue, if my diagnosis is correct. If I want to put the new brake switch in myself, how does one go about adjusting it correctly?

#2 "OIL AT TEMP" light flashes while driving:

Comes on randomly. If the car sits a bit and I go back out, it only comes back on when driving for about 15-20 minutes. Driving conditions are various.

Fluid changed at 30K, now at 42K, level is good, color is good, odor is good.

Coolant level good, car does not run hot at all (only say this cause on another board someone mentioned transmission cooler and coolant)

My thoery is this based on info I found in an inquiry by someone who had something similar on ask.com or one of those sites.

Theory: my brake switch is obviously toast, I have read that a faulty or bad brake switch can cause the tranny to act differently or shift differently as it's not sensing the brake pedal being depressed while slowing down.

Is it possible that the bad brake switch is causing the blinking "OIL AT TEMP" light while driving?

The coincidence of both starting at the same time, makes me think yes, but by no means am I an expert on these things.

So, I'm picking up a brake switch tomorrow and hope it's a simple 1 2 3 thing to replace eventhough I am not sure at what height to put it.

With regards to the OIL AT TEMP flashing light, which now happens every day, a few times a day, if I get lucky and it goes away, great, if not:

How do I proceed as the car still is under the 5 year 60K powertrain portion of the warranty.

The crazy thing, I call up my dealer and he say "$115" to diagnose the blinking light. I tell him and he agrees, that it's most likely tranny related and that if it is, I am under warranty for that. He says $115 and we'll go from their. What the hell is that all about???

So, I tried to keep my ramblings brief, what ya think, will I get lucky and the brake switch will solve the other issue, or do I have more serious concerns with the blinking "OIL AT TEMP" light?

I can honestly say, the car feels as good as day one, the only thing worth mentioning is that I think I can feel the car engine braking more than normal, if that makes any sense, which I thought as of tonight was related to the brake switch futzing up the tranny shifting a little.

Thanks for taking the time to read all this.

ps - if I am totally off of anything please let me know, I always help others on my local suby forum in NY and if someone else should run into these issues, I would love to be able to help them correctly :)

Edited by kero, 28 May 2011 - 01:13 AM.


#2 Cougar

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Posted 28 May 2011 - 01:51 AM

If the middle brake light turns on while the other ones don't then the trouble isn't with the switch for the brake lights. Check the emergency flasher switch instead. Try cycling it a few times to see if that helps. Also check for a loose connection. I wouldn't change anything out until the trouble is pinned down to the real cause of the problem. Guessing at the cause of the trouble will cost you extra money that would be better spent on a test light probe and a service manual.

There should be codes stored that will show why the transmission light is blinking.

Edited by Cougar, 28 May 2011 - 01:58 AM.


#3 kero

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Posted 28 May 2011 - 09:35 AM

^^ All three brake lights don't work and the P0719 clearly points to a bad brake switch. I have checked the connector on the brake switch itself, its very very tight, where else is is there a connector that I should check with regards to this code? Since I was unable to get out of park quite a few times with depressing the release button next to the shifter, this def points to a faulty or bad brake switch, does it not?

According to the OBDII code list

- Brake switch circuit is open or shorted.
- Poor brake switch circuit connection
- Faulty brake switch

Also, I understand your point about the codes for the TCU, but why would a dealership charge me before doing a thing to diagnose when they know it's a warranty issue. It's not like I'm gonna get the "OIL AT TEMP" light blinking for bad brake pads or something like, that would clearly not be covered. It should be a simple drop it off and fix it type of deal. I don't understand why they are trying to make it like the problem is with some that is out of warranty when the service manager clearly said on the phone, it sounds tranny related?

I am still waiting for someone to chim in to see if the brake switch can be causing the "oil at temp" light issue since I have read several times that in modern cars, a bad of faulty brake switch can cause the tranny to act up or shift differently than normal.

Edited by kero, 28 May 2011 - 09:49 AM.


#4 Cougar

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Posted 28 May 2011 - 03:20 PM

If you don't have at least a test light probe to check for power I suggest you get one. Make sure power is at least getting to the brake switch. If that checks out then see if power is getting passed it. There could be a problem in the wiring beyond the switch that is causing the trouble.

I'm not sure what to say about the diagnostic fee charge. If your car has a warranty all the charges should be covered, including any labor charges. If the warranty is limited then maybe that is the issue.

Edited by Cougar, 28 May 2011 - 03:24 PM.


#5 kero

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Posted 28 May 2011 - 05:23 PM

Guys,

Picked up the switch today, my buddy works at the dealership and I got it for $30, I'll install that tomorrow.

The spring plunger on the new one feels like it has very good resistance when pushing in the plunger, the one on the car now, it pushes it with very little pressure.

I'll report back tomorrow once that is installed, they did advise me at the parts department that the switches do fail and there is not set time frame at which they do.

They also told me to just bring in the car and tell the person writing it up about the "OIL AT TEMP" flashing light, they said if it's warranty work, which they agree it is, I shouldn't have any problem, so again, the guy I spoke with on the phone was just be a turd.

Will update on that when car goes in, hopefully wed of this coming week.

#6 kero

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Posted 29 May 2011 - 05:33 PM

UPDATE: Put in the new brake switch today, cleared all codes via battery disconnect, left the lights on to drain all power, let the car sit for about 20 minutes, hooked battery back up, let car relearn idle for about 15 minutes, took it on a 80 mile trek today in all sorts of driving conditions, brakes lights are now working fine and no CRUISE BLINKING and NO OIL AT TEMP light came on today at all.

Before I did this, the past 3 days, oil at temp light would come on blinking, numerous times while driving the car.

Keeping my fingers crossed that the brake switch and brake switch CEL I got, was causing the tranny to sense there was a problem since the P0719 code, indicated that the tranny was not sensing the brake being applied while slowing down, etc etc.

Let's see how the next few days goes. If all is well, problem solved, if not, going to the dealer to be checked.

#7 Cougar

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Posted 30 May 2011 - 06:22 PM

Thanks for the update. I'm sure you will be good to go now. Good job.

#8 kero

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Posted 30 May 2011 - 10:02 PM

Guys, thanks for your feedback and comments, I mean that sincerely.

I am still at a loss as to how the faulty brake switch would cause the "OIL AT TEMP" light to keep blinking while driving? I have some theories but it's all based on the numerous different threads and posts across various boards and inquiries.

Now, today, did another 25+ miles of mixed driving again, no "OIL AT TEMP" light blinking while driving and checked brake lights again for good operation.

All seems well, for now.

Is it safe to assume that if between yesterday and today, I did a total of 100 miles of mixed driving, that the problem would have popped up again.

Of course, I hope the answer is yes LOL!

#9 grossgary

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Posted 30 May 2011 - 10:17 PM

the OIL AT TEMP light also serves as an indicator that the TCU (transmission control unit) sees something wrong. doesn't have to be anything temp related, the light is just an indicator that the TCU doesn't like something. since the brake is partially integrated into the transmission function (needing to be pressed to change gears), I'm not that surprised the light cleared.

#10 Fairtax4me

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Posted 01 June 2011 - 12:31 AM

E: DTC P0719 BRAKE SWITCH CIRCUIT LOW
DTC DETECTING CONDITION:
Brake switch malfunction, open input signal circuit
TROUBLE SYMPTOM:
Gear is not shifted down when driving a down hill.

08 FSM was the closest I could find, but that's Subaru's definition for P0719.

Anyway, short answer is the TCU relies on input from the brake switch to determine when to downshift. An erratic signal or no signal can confuse the TCU, it recognizes there is a problem and illuminates the AT OIL TEMP light as a signal that something is wrong.
The BCM (Body control module) reads the signal from the brake switch is erratic, stores the code and illuminates the MIL.

#11 kero

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Posted 01 June 2011 - 01:26 PM

^^ Most interesting but yeah, I had a feeling the bad brake switch def affecting the tranny in some way, but now it makes more sense.

Thanks for that info :)




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