Can you add an audible alarm to a warning light?

15,575

Asked by Nov 13, 2015 at 10:57 PM about the 2010 Subaru Outback 2.5i Limited

Question type: General

The Subaru Outback models from 2010-2014 have a warning light to alert you
if the car starts to overheat,   flashing light is warning you and solid light
means  you're starting to actually overheat.   SO,  CAN YOU ADD AN AUDIBLE
ALARM TO THE LIGHT AS SOON AS IT STARTS FLASHING?

46 Answers

59,955

Yes it can be done,but would need to be wired in to the tempreture sending unit.

1 out of 1 people think this is helpful.
40,015

I would check Radio Shack for a 12V buzzer that could be wired in to the circuit.

1 out of 1 people think this is helpful.
40,015

I have to disagree with the first answer though. The buzzer needs to be energized when the light is energized. Putting the light and buzzer on the same circuit should do it.

1 out of 1 people think this is helpful.
40,015

Mark, another alternative would be to wire in an after market temperature gauge instead of relying on the idiot light.

1 out of 1 people think this is helpful.
7,430

What we are dealing with is a signal that is probably less than 100ma ...You need to be very cautious that you don't overload the signal from the ECU. This is what I would use~~~Approximately 1 inch in diameter x 0.875 inches in height, it packs an explosive sound output of 103 dB at 2 feet. The M-80 pc mount and PM-80 panel mount piezo electric alarms feature an expanded voltage range of 5-15 Vdc.

2 out of 2 people think this is helpful.
15,575

Full_of_Regrets, yes, I like your suggestion, but, where do you install the actual guage in the car? The audible signal would cause me to look at the instrument cluster. Yes, idiot lights are not ideal, but, they can work and are elegantly installed in the speedometer cluster. So, how do you integrate the gauge?

1 out of 1 people think this is helpful.
15,575

So, you guys think this is a good idea, someone on the forum had their Subaru Outback overheat when the light went unoticed.

40,015

There are gauges that can be mounted on the dash, under the dash and on the A-pillar next to the windshield. You would likely have to install another temperature sender but the new gauge would come with instructions.

1 out of 1 people think this is helpful.
146,125

Mark, your Subaru only has 'idiot lights' and not a temperature gauge? That surprises me ...

3 out of 3 people think this is helpful.
146,125

Mark, your Subaru only has 'idiot lights' and not a temperature gauge? That surprises me ... Does you dash instrument cluster look like this..

3 out of 3 people think this is helpful.
146,125

or this?

3 out of 3 people think this is helpful.
146,125

I don't know about you guys, but when traveling I glance down at all gauges often. Maybe it's the aircraft history of mine, that's the cardinal rule of flying...No, I was never a pilot but still...

3 out of 3 people think this is helpful.
146,125

Also Tom, 103 dB would certainly get your attention. Wow!

3 out of 3 people think this is helpful.
15,575

FordNut, yes, unfortunately, there's no temperature guage. On the 2010-2014 models, they decided to install a MPG gauge which is helpful for watching your fuel-efficiency, but, I understand there's no way to replace this with a temperature gauge, read this somewhere on the forum, I think.

1 out of 1 people think this is helpful.
15,575

FordNut, neither of those pictures are the instrument cluster of the 2010-2014 Subaru Outback cars, here's the real dashboard, see below,

1 out of 1 people think this is helpful.
146,125

I would choose a temperature gauge - if I had a choice, I can get best fuel economy with driving habits, and whatever gas gets used gets used. I want to know what temperature my engine is running at all times. Like I say, that really surprises me that Subaru thinks people are more concerned with that little tiny bit of gas they save than the operating condition of their engine. Hmmmm

3 out of 3 people think this is helpful.
146,125

i want to put a train horn on my car.

3 out of 3 people think this is helpful.
15,575

Full_of_Regrets, you wrote, "There are gauges that can be mounted on the dash, under the dash and on the A-pillar next to the windshield. You would likely have to install another temperature sender but the new gauge would come with instructions" Thanks, but, if the gauge was anywhere under the dashboard, it would be hard to see. And, mounted near the windshield would be too much of an obstruction. I think I'll just have to either find another solution like the alarm or buy a 2015 or newer model. Subaru restored the temperature gauge on the new cars.

15,575

FordNut, train horn?. That's pretty loud, be careful, and by the way, check your email messages.

15,575

Tom, anyway to tone down that 103 dB? My Toyota has a signal beep that goes off if it runs low on fuel and reminds you to add fuel soon.

146,125

Yup, I see what you mean . This is labeled 2013 Outback mpg, tach, speeedo, and fuel. I would not buy a car without a temperature gauge, but that's just me

3 out of 3 people think this is helpful.
146,125

That's another thing. I never allow my car to get below ½ tank. Again, that's just an OCD with me. I have had that habit since the 70's, you never know if or when the gasoline supply goes for any number of unpredictable reasons. yeah, I know it's stable now and gasoline stockpiles are high. Buy if for some reason, I don't know how many of you guys are old enough to remember having to wait in line for hours - literally- to get gas. It got so bad, it created a job market, pay a guy to wait in line for you in your car. Then the guy at the station would refuse to sell you gas if your gauge was above ¼ , no cans allowed, no boats

3 out of 3 people think this is helpful.
3,230

Yes, to install a proper gauge you'd need to get creative and locate its temp sending unit somewhere useful. I like Tom's idea of a parallel wired piezo alarm. Quick and easy. I wired a couple of these on my Miata as the down-tilted steering wheel blocked turn signal dash bulbs. Subaru's actual cooling systems are quite robust, using very durable water pumps and high-flow t-stats that very rarely fail. Since MOST overheating events were caused by head gasket issues it's interesting hubris on their part to remove the gauge once the HGs improved.... Yet a clogged or burst hose or radiator can cook up a mess too, so I always like the use of a gauge. Once a warning light comes on it's too late and you usually have Mt Vesuvius erupting under the hood as you pull over. It's interesting that many manufacturers are now running simple intake vacuum gauges backwards and labelled as eco or mpg gauges. Cute.

7,430

Eliminating a temperature gauge is just another example of book-keepers building cars. A temperature gauge is more than a warning device ,,, I can actually see how my car is performing ... I can tell if it's running hotter than normal and investigate the cause before it gets to the Alarm. ~~~~~~~ BTW Mark ,,,, if someone didn't see the light ... I seriously doubt they would check a gauge

3,230

I like a gauge as much to indicate coolant warmup in the winter so as to not rev a cold motor. I know some makers use little blue lights for such purpose...certainly better than nothing. For Subarus a partially occluded radiator (exterior airflow by leaves or dried mud; coolant by old deposits sometimes blocking a rear heater hose)...or a partially filled radiator (russian roulette!) will manifest as a slightly creeping temp gauge under stress (hwy or uphill running). Thus a gauge can be a useful indicator to remedy the situation before warping heads or blowing gaskets. That bean counter must've been a new hire....

7,430

I hope most of us will agree that in the last 10-20 years ...Overheating is much more serious than it was in earlier cars ... of course it's due to aluminum being the dominant metal in cars engines. Nothing in the "repair world" is sadder than a almost new car's engine being fried beyond repair due to over-heating. Maybe designers will figure out a better way to protect engines fron this "epidemic'

1 out of 1 people think this is helpful.
3,230

It's unlikely, as high efficiency and lighter mass requires pushing the thermal envelope. Remember the first Honda CVCC in the middle 70s? They had to run them REALLY hot to avoid using a Cat Conv. Can you say "cumulus cloud clogging concrete corridors"? Happened to me in Boston on a bridge at rush hour in '98.

1 out of 1 people think this is helpful.
7,430

FordNut ... Ah .. the sound is adjustable. and it goes directly in line with the idiot light. Mark asked a question and I gave him something that IMO is what he wanted ... it seems that most answers here are straight from "Shade Tree Mechanics". in that~You would stick a gauge here or mount something there .... Well ... when I was a lad you could do that ... and in many ways you still can but before you embark on any project regarding an ECU I/O .. you better be damn well sure the current draw won't drag that Algorithm into failure mode Answer the question and consider that Mark's an intelligent guy .. and He has no doubt thought of alternatives. Mark asked a question and I answered his question. If MARK ASKED WHAT I WOULD DO I WOULD HAVE TOLD HIM TO REPLACE THE LIGHT WITH A HIGH INTENSITY BLINKING LED

1 out of 1 people think this is helpful.
15,575

Thanks for your answers on the alarm and the suggestion about the high intensity LED light. It's also good news about the Subaru having a robust cooling system, when working properly. According to Subaru, the warning light has two phases, the first is that it starts blinking, telling you that the car is "warning you " that you are about to overheat. And when it stays fully illuminated and stops blinking, you're starting to actually overheat. So, the real question is how much time do you actually have before that occurs. I read somewhere that most people are going to notice a light on their dashboard before they notice that the gauge is creeping up to the red zone. And, I wonder if the gauge is not any better than the idiot light and here's why? I had a radiator failure in my old Honda Accord and it had a temperature gauge, that thing just shot up on the dial like a rocket, all happened pretty fast. Good thing I noticed it. Many cars including my Toyota Prius don't have any temperature gauges, oil pressure, alternator etc. So, does it depend on the accuracy of this instrumentation in your car? I'm still liking the idea of an alarm to catch my attention with the light. Don't they have this sort of warning systems in aircraft?

15,575

TheSubaruGuruBoston, yes, the Subaru does use a blue light for indicating that you car is cold. I usually let it warm up for a minute or more before driving off. And, yes, Subaru did change the head gaskets on the 2010 and newer cars. I suppose I'll find out about the head gaskets issue, I just wanted to be a prudent as possible in not overheating the car. So, you think my independent mechanic could carefully install an audible device in conjunction with the sensor or would you recommend taking this to the dealer?

15,575

Found this online, see picture attached,

3,230

ark, I don't know what YOUR wrench is capable of, but if I were you I wouldn't stand over his shoulder telling him what you know, and what to do!

15,575

He is pretty capable, but, it's not a standard procedure, might ask for the wiring diagram. What should I tell him?

3,230

I'd try wiring the piezo IN PARALLEL with the idiot first; otherwise their resistances will act as voltage drops with each other...and maybe NEITHER will work. I'd be surprised if current draw affects the ECU in any way. Nevertheless I'd use a low current one. I also think you might be bordering on paranoia. If an HG goes or a hose bursts those warning lights will blink in no time, and I don't think an audible alarm would help as much as an assistant to help followers steer away from the wet cloud you're jetting behind you. Ha!

1 out of 1 people think this is helpful.
7,430

It's possible to wire the Piezo so the hotter it gets .... the louder it gets after it crosses the alarm threshold ... perhaps when it gets so loud that the drivers eyes become crossed ... he will stop

15,575

TheSubaruGuruBoston- maybe you're right and I'm being paranoid about this, and the solution may be too much for a simple problem. Here's a picture showing where the warning light is, same place as the blue light showing the car is not warmed up. And, since it's part of the same instrument cluster showing the miles per gallon and pretty obvious, I probably will notice this. It's not a small light underneath the speedometer like the tire pressure guage and in its own and the only light in this quadrant of the panel. In other words, you'd have to be very unobservant not to see this. See attached picture below, you'll see what I mean.

15,575

And that warning light illuminates for a few seconds showing that it's working every time you start your car. Only time it's blue is when the engine is cold.

15,575

Found out today that this is impossible to do. The integrated instrument cluster is VERY COMPLICATED and a sealed unit. Opening up this can of worms is worse than just the flashing light. Oh, there's no audio signal if the light flashes, just hope that you notice it. Actually, my understanding is that Subaru cooling systems are so robust, it may never happen. Just keep up on your regular service intervals.

3,230

Mark, we told you several ways to do it. But of course you say it's impossible....

15,575

Ernie, I recall your saying that quote earlier saying. " don't think an audible alarm would help as much as an assistant to help followers steer away from the wet cloud you're jetting behind you."

15,575

There's two problems with doing this, first, the light that illuminates for a cold engine and hot engine are the same light on the instrument cluster. One person to!d me that this might be accomplished with a heat sensor that tied into the circuit that illuminates the "red light", but, my very savvy stereo shop removed the instrument cluster and looked behind to find a number of unmarked circuit board ports, and told me that this might take days to figure out and they were not sure they could even do it. I called a Subaru dealership and Galpin Auto Sports here in LA. Galpin Auto Sports in case you didn't know has built some of the most tricked out cars in Hollywood. They told me that even if they could do it, they thought it was cost prohibitive. Finally, I thought about what you also said, Subaru's have a robust cooling system. So, I'm hoping not to have a problem or watch for the flashing light.

15,575

Ernie, in case you or others are unfamiliar with this place, see https://en.m.wikipedia.org/wiki/Galpin_Auto_Sports

3,230

I hope I'm spelling perseverate correctly.

15,575

Some people reading this thread might benefit by knowing that this is MORE COMPLICATED than it appears. Also, there's the issue of the same warning light for cold and hot engine is on the same circuit. I thought we were having a dialog about this and it appears that you would rather make fun of it, and make snide remarks. I don't appreciate it . I asked the question and you commented on it. You have been gracious in other exchanges , but. I wouldn't say this was one them. At least, David H. ( aka, Fordnut), RIP, was very helpful and informative in all instances. He was a model contributor to this forum.

3,230

Pardon.

15,575

Yes, of course.

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