General Question

rojo's avatar

Engineering types, why would my air bag warning light come on upon startup when the weather is cold?

Asked by rojo (24102points) December 14th, 2018

Or what passes for cold here in Texas.

When I start my truck the warning light is supposed to come on for a few seconds and then go off.

When the weather is 45 degrees or below it comes on and stays on. This will happen every time. If the temperature goes up above fifty during the day it no longer stays on when the truck is started. Same if the next day, if the temperature is back up then it acts as it should. If it drops below the 45 degree level that afternoon then the problem reinstates itself.

What gives? What do I need to do to correct the problem?

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11 Answers

Dutchess_III's avatar

Maybe it’s frozen and it’s warning you that it’s frozen?

KNOWITALL's avatar

My mechanical friends just say “vehicles act weird in cold weather, it’s usually nothing”. haha

LuckyGuy's avatar

It could be dozens of things.
I’ll guess the passenger seat occupancy sensor is acting up. Was anything ever spilled on the passenger seat?

What does the OBD-II diagnostic say?

rojo's avatar

No, @LuckyGuy nothing has been spilled on the seats. I don’t think it is the passenger seat, that has its own light. This is the one for the driver air-bag according to the book. I have not had it diagnosed yet. I asked one of the service reps at the Ford dealership and he just shrugged and said if it works correctly at “normal” temps it is probably nothing. I read online that there is some kind of coding built in to the system that the number of times it flashes will give some idea of the problem but it doesn’t flash, it just stays on.

Tropical_Willie's avatar

Mine does the same thing but only once or twice a winter. Also a Ford (Taurus).

josie's avatar

My dad never took any problem about the car seriously until it had “warmed up”. What ever that meant.

ARE_you_kidding_me's avatar

Odds are there is a loose contact somewhere in the sensor chain or the sensor itself is having issues. You can get a cheap OBD II reader and see what it says but it’ll probably just throw a code telling you what you already know. Or… as in the case of my car the airbag light has a series of blink codes that tells you certain things like it has lost power. I have to reset it every time I disconnect the battery. Generally though the airbag will not deploy if you get an alarm so keep that in mind.

Call_Me_Jay's avatar

You can get a cheap OBD II reader

I have one of those. It was about $5 from eBay. With a free phone app it’s a great tool.

Also, I know some auto parts stores will let you borrow a scanner for free.

kritiper's avatar

A code reader won’t read any codes unless the “check engine” light is on.
Cars are designed to run when warmed up to normal operating temperature, so if the light goes out when the car is warm, it’s most likely OK, as someone above noted already.
Other dash lights are supposed to come on when the key is turned to the “engine run position,” the position of the key just before spring resistance is encountered, just before the starter engages. This is so the dash lights can be checked for proper operation.

ARE_you_kidding_me's avatar

There are more codes than just “check engine” and a code reader will read a good number of them. Some don’t even have dash indicators at all.

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