Parking brake switch malfunction - PN 84390-WAA01

[Jaxness]

With no prior issues, I went to the airport the other day to pick my husband up. I have 15+ years of habit always using the parking brake when I park the car - so I always engage it in the Supra.

Pulled into a parking spot, put the car in park, pulled up on the parking brake switch, and immediately got the error "Parking brake malfunction. Secure vehicle from rolling when parked."

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I've had a few error messages pop up randomly before so I assumed when I came back to leave, the message would clear itself by shutting the car off and turning it back on. It didn't.

When I started the car, I closed the message and put the car in reverse. It showed it went into gear on the shifter, but I didn't *feel* the car change gears like I normally do - it stayed completely still - so I had no idea if it actually went into gear. I tried the same thing putting it into drive - no change.

I spent about 45 minutes trying to clear the message by disconnecting the battery a few times. I didn't find anyone else online who had experienced the problem before, so I was kinda stuck.

I was afraid to try and step on the gas pedal while in gear because I didn't want the car to jump into the cement pole in front of my parking spot or backward into another car so I just left it there and called an Uber to get home until I could come back the next day with some tools to poke around.

The next day I eventually gave up searching for the damn gremlin causing the problem and I ended up giving the car some gas while in reverse. It hesitated for a second like it kinda felt "stuck" but then it drove like normal and got me home. The message never went away.

Took it to the dealership yesterday and they kept it overnight. The final consensus was to replace the parking brake switch (part number 84390-WAA01) which wasn't in stock, of course, so I'll have to bring the car back in a couple of days to have them replace it under warranty.

While they had my car in for diagnostic, I went ahead and had my 21TA04 safety recall done and now I get the full-screen Apple CarPlay, yayyy. Haven't had a second to check and see if I'm one of the lucky ones who can reload their MHD tune afterward.

I'll report back to confirm it resolved the issue. Just wanted to get the info out there to help any other poor souls that might encounter the problem.

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[Escapist]

Well that's a new one. Also, I'd advise to contact MHD and verify your car is tuneable post recall without a bench unlock. I have BM3 and I was informed by Protuning freaks that if I were to try to flash my car without a bench unlock post recall, it would brick the ECU.

 

[Rocksandblues]

We have a parking brake??

 

[Jaxness]

Well that's a new one. Also, I'd advise to contact MHD and verify your car is tuneable post recall without a bench unlock. I have BM3 and I was informed by Protuning freaks that if I were to try to flash my car without a bench unlock post recall, it would brick the ECU.

It is. And I’ll do the unlock ASAP because the stock tune is wayyyyy too slow?

 

[mvtte]

just wondering..

are y'all engaging your parking brake by first shifting into park then press brake pedal and pull on electronic parking brake button? or while in drive, press brake pedal, pull on electronic parking brake button then shift into park?

 

[Jaxness]

just wondering..

are y'all engaging your parking brake by first shifting into park then press brake pedal and pull on electronic parking brake button? or while in drive, press brake pedal, pull on electronic parking brake button then shift into park?

Put the car in park, release the foot brake, engage the parking brake.

Just recently (last week) started having a similar issue where the car won’t move in reverse. It goes into gear, but doesn’t move when I press the gas - almost like when the safety sensors detect you’re about to hit something. But I was in an empty, flat, parking lot.

I tried to back up twice before I gave up, put it in drive, moved forward a couple feet, and then tried reverse again and it worked. This issue has happened twice now.

 

[Mkva90]

Put the car in park, release the foot brake, engage the parking brake.

Just recently (last week) started having a similar issue where the car won’t move in reverse. It goes into gear, but doesn’t move when I press the gas - almost like when the safety sensors detect you’re about to hit something. But I was in an empty, flat, parking lot.

I tried to back up twice before I gave up, put it in drive, moved forward a couple feet, and then tried reverse again and it worked. This issue has happened twice now.

my dumbass decided to torque the wheels down while the car was still in the aur. not sure if that caused it but the car will go into gear but won't rev high enough to over power the parking brake.

 

[zrk]

Your car will need a bench unlock, but you're still tunable.

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