# ABS/Hill Assist Warning Lights - can't shift? **URL:** \ **Category:** In My Humble Opinion\ **Created:** [January 9, 2016, 7:56pm UTC](https://boards.straightdope.com/t/abs-hill-assist-warning-lights-cant-shift/742620 "2016-01-09T19:56:39Z")\ **Posts on this page:** 5\ **Page:** 2
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [February 27, 2016, 1:25pm UTC](https://boards.straightdope.com/t/abs-hill-assist-warning-lights-cant-shift/742620/21 "2016-02-27T13:25:41Z")
> [@gigi](#): > > Sorry to be blogging about this, but since there was some interest – the dealer pulled the same code as the local garage, C1531 Brake Light Switch Fault. This time “tech found failed brake switch”. He explained it as the brake not knowing I was braking. Makes sense it wouldn’t let me shift out of Park – the other warning lights were misleading. > > Supposedly I will have no more problems with this, and it was covered under the warranty. Not necessarily misleading, the switch both operates the brake lights and can be used to tell the ABS module or PCM that the driver is indeed stepping on the brake; stability control and hill start assist both need to know that. It probably does a circuit check when you start the car, found a fault, and disabled those systems (and put the warning lights on) because it can no longer be sure of the state of the brakes. ---
**Author:** ![GreasyJack](https://avatars.discourse-cdn.com/v4/letter/g/df705f/32.png) [@GreasyJack](https://boards.straightdope.com/u/GreasyJack)\ **Post date:** [February 27, 2016, 6:33pm UTC](https://boards.straightdope.com/t/abs-hill-assist-warning-lights-cant-shift/742620/22 "2016-02-27T18:33:58Z")
It’s also of course is what tells the computer that your foot is on the brake so it unlocks the shift-lock solenoid. If the switch had failed in such a way that the self-test didn’t detect it (i.e. if the switch came loose and the little plunger wasn’t hitting the brake pedal arm anymore) then you would have had the shifter locked without any warning lights. ---
**Author:** ![gigi](https://avatars.discourse-cdn.com/v4/letter/g/a587f6/32.png) [@gigi](https://boards.straightdope.com/u/gigi)\ **Post date:** [February 27, 2016, 9:03pm UTC](https://boards.straightdope.com/t/abs-hill-assist-warning-lights-cant-shift/742620/23 "2016-02-27T21:03:29Z")
> [@steatopygia](#): > > Thanks for the update. > I hope it is the last one and the car is truly fixed. 🙂 Thanks! 🙂 And per your post above, I did not mention to the dealer about having taken taking it anywhere else. > [@jz78817](#): > > Not necessarily misleading, the switch both operates the brake lights and can be used to tell the ABS module or PCM that the driver is indeed stepping on the brake; stability control and hill start assist both need to know that. Sorry, I meant misleading in the sense of the overall problem wasn’t specific to ABS/Hill Assist. ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [February 28, 2016, 1:37am UTC](https://boards.straightdope.com/t/abs-hill-assist-warning-lights-cant-shift/742620/24 "2016-02-28T01:37:16Z")
> [@gigi](#): > > Sorry, I meant misleading in the sense of the overall problem wasn’t specific to ABS/Hill Assist. eh, that’s the nature of on-board diagnostics. They can only say “hey, there’s a problem over there.” it still takes a trained meatsack to figure out what’s causing the problem. incidentally, this is why a lot of auto parts stores will offer free trouble code checks. They hope you’ll buy a ton of parts from them trying to find the problem with your car. ---
**Author:** ![gigi](https://avatars.discourse-cdn.com/v4/letter/g/a587f6/32.png) [@gigi](https://boards.straightdope.com/u/gigi)\ **Post date:** [August 30, 2016, 5:19pm UTC](https://boards.straightdope.com/t/abs-hill-assist-warning-lights-cant-shift/742620/25 "2016-08-30T17:19:59Z")
After coming on for maybe a day at a time a couple of times, and then resolving themselves, the lights were back on for a week. I took it back in and they confirmed that the new replacement part they had put in had failed. But, Subaru had acknowledged it was defective so now they had a new improved part to put in. We’ll see how long it lasts! [Previous page](https://boards.straightdope.com/t/abs-hill-assist-warning-lights-cant-shift/742620.md?page=1)