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What is an Ignition Switch?

A car's ignition switch and key.
A vehicle's battery is connected to the starter via an ignition switch.
The ignition switch can also be activated via a push button system.
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  • Edited By: Niki Foster
  • Last Modified Date: 23 August 2014
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A car's ignition switch serves several purposes. First, it allows you to control the power to many of the car's accessories, preventing accessories from running down the car's battery when the car is parked for a long period of time. The ignition switch also serves the far greater purpose of connecting the starter to the battery, allowing the battery to send a powerful surge of electricity to the starter when the car is being started.

The term ignition switch is often used interchangeably to refer to two very different parts: the lock cylinder into which the key is inserted, and the electronic switch that sits just behind the lock cylinder. In some cars, these two parts are combined into one unit, but in other cars they remain separate. It is advisable to check your car's shop manual before attempting to purchase an ignition switch, to ensure that you buy the correct part.

In order to start a car, the engine must be turning. Therefore, in the days before ignition switches, car engines had to be turned with a crank on the front of the car in order to start them. The starter performs this same operation by turning the engine's flywheel, a large, flat disc with teeth on the outer edge. The starter has a gear that engages these teeth when it is powered, rapidly and briefly turning the flywheel, and thus the engine.

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The ignition switch generally has four positions: off, accessories, on, and start. Some cars have two off positions, off and lock; one turns off the car, and the other allows the key to be removed from the ignition. When the key is turned to the accessories position, certain accessories, such as the radio, are powered; however, accessories that use too much battery power, such as window motors, remain off in order to prevent the car's battery from being drained. The accessories position uses the least amount of battery power when the engine is not running, which is why drive-in movie theaters recommend that the car be left in the accessories mode during the movie.

The on position turns on all of the car's systems, including systems such as the fuel pump, because this is the position the ignition switch remains in while the car's engine is running. The start position is spring loaded so that the ignition switch will not remain there when the key is released. When the key is inserted into the ignition switch lock cylinder and turned to the start position, the starter engages; when the key is released, it returns to the on position, cutting power to the starter. This is because the engine runs at speeds that the starter cannot match, meaning that the starter gear must be retracted once the engine is running on its own.

Either the ignition switch or the lock cylinder may fail in a car, but both circumstances have very different symptoms. When the ignition switch fails, generally the electrical wiring or the plastic housing develops problems. The car may not turn on and/or start when this happens. Also, the spring-loaded start position could malfunction, in which case the starter will not engage unless the key is manually turned back to the on position.

When the lock cylinder malfunctions, however, the operation of the key itself will become problematic. If the tumblers become stripped, the lock cylinder may be able to turn with any key, or you may be able to remove the key when the car is on. If the tumblers begin to shift, the lock cylinder may not turn. Sometimes the key can be wiggled until the lock cylinder turns, but it is important to remember that this is only a temporary fix.

Replacing an ignition switch can be tricky business, particularly in newer cars, because of the anti-theft devices used in cars. Once the ignition switch is separated from the back of the lock cylinder, the car can be started with a screwdriver, making it vital that this switch be difficult to get to. It is important to consult a shop manual before attempting this kind of repair, as the anti-theft devices may require special tools; attempting to remove an ignition switch without the proper tools can render the car inoperable.

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anon931802
Post 55

If it were me, I would use the right brake light. Sometimes I use the left but I found the right puts out more dbs. I hope you find this helpful.

anon350727
Post 54

I have an old Daewoo Espero 1995 model car. My ignition switch is broken and there is no available replacement around my place so I was hoping to replace the whole lot with just switches that will work like the previous one. That is, one switch for accessories, one switch for on, one switch for starting and so on and so forth. Can it be done?

anon326992
Post 53

I have an 02 cavalier. The car won't even click or make noise when I turn it over. I replaced the starter with a brand new one, put in a new battery, checked all the fuses, headlights, lamp, radio and four way blinkers. Nothing on the dash works. Please help!

anon291215
Post 51

I have jeep grand Cherokee and put a viper alarm remote starter on it, and the problem is my key won't crank my jeep and only thing I can do is to push the remote starter button and it cranks automatically. I want to know if the ignition switch need to be replaced.

mrharvy
Post 49

Does anyone have an answer to anon228273, Post 46? Mine is doing the same thing.

anon244715
Post 48

My 2006 mazda 6 is stuck in third gear. It has been sitting for a week. I had to jump start it twice, then drove it all day, then I turned it off then get back in 20 minutes later and it has been stuck ever since.

I went to auto zone the code said it was a knock sensor then got back home and called a mazda service tech and he said that has nothing to do with the gears, so what do I believe?

calemonlaw
Post 47

Ignition switch problems are not as uncommon as people might think. Please help. I have replaced the starter, replaced the ignition switch and the car does not start- or turn over. Everything turns on, but that's all. I tried to push start the car, and it starts easily. The main wire from the battery to the back of ignition switch has not not been replaced. I need help for my problem.

anon228273
Post 46

I have a 98 Pontiac Sunfire. I changed the heater core and put everything back together and turned the key. All the dash lights came on and all the instruments worked, but when I went to turn the engine over, everything quit -- like died instantly. I have to disconnect the battery and reconnect it to get anything to come back on and when I do, everything works again.

I got it to start by waiting ten minutes with the ignition on and then hitting the key to start it. But when I came home and parked it, an hour later it was doing it again. It's such a headache. Pontiac won't give me any answers other than we can send a tow truck, but why can't they just tell me what could be causing this so I can troubleshoot? Why do these cars have to be so ridiculous?

anon224662
Post 45

I need to find the key number. My factory security alarm has prevented my 95 Buick Riviera from starting.

anon210838
Post 43

I have a 1989 chevy cavalier z24 that all of a sudden died while driving. It wouldn't start back up, then a few days later it started, and drove around block then died again? I changed the ignition module, many sensors, fuel filter and alternator, and it still won't work. any suggestions?

anon185532
Post 42

I have a 98' Izuzu Hombre. It seems that when we try to start the truck, we get a loud clicking sound. it's coming from the starter. we replaced the starter, and tried starting it, and we got the same thing. What could possibly be wrong?

anon166998
Post 41

I have a 2003 Pontiac Grand Prix. I noticed lately I've been having a problem turning my ignition switch to the off position when parked. I usually have to fiddle with my steering wheel to get the switch in the correct place. They say I need a new ignition switch but I don't want to have a different key to my car, just to start it up. Any suggestions? --C Ivan

anon157208
Post 40

I have a 2002 f150 super crew and I had it to a ford dealer they said nothing wrong. when i get home, take the keys out this is what happens. The dome light comes on and the fan. I have to unhook the battery cable in order to completely shut it off. what could it be? can't figure it out. help!

anon155590
Post 39

The mechanic put a heater core in my car and had to drop the dash. He damaged the first core and I had to get another one. He had my car four days when he tore up the ignition system. I don't have security on the car so I want to know what he did to make the key release in on position and the car won't shift out of park but it will start. There was nothing wrong before he started taking parts from the steering column and replacing them with junk yards parts.

I don't want junkyard parts in the electrical system. It is six days now. can someone help solve this problem. I think he forced the key out in the wrong position. I'll try to fix it so I can take to the Chevy house. It's a 6 cylinder Jimmy 4.3.

Metju
Post 38

I recently bought a 1991 Ford Bronco to fix up. I got it running, and shortly after it died while I was pulling into a parking lot at work. It wasn't starting. Had the battery tested and it was fine. Replaced the starter and the solenoid and it started up just fine.

Then today, (one day later) I drove it to work and noticed the battery gauge was really low. I got to work and did my thing and headed home, which is only about a mile down the road. When I pulled into my parking spot and turned the ignition off, then engine turned off but it continued to sound as if it was trying to start.

I opened the hood and everything was still turning, just without firing. It eventually stopped when the batter no longer had enough charge to keep this act up.

Also, the engine was running funny. When idling and coming to a stop, the engine would almost die but would come sputtering back to life. Are these two issues related? Any advice would be great. I'd like to get this thing running good so I can finally enjoy my toy!

thumkey
Post 37

Don't laugh. I have an '89 Olds 88. My problem is this: I can be driving along and all of a sudden i will lose my lights and radio but the car stays running.

Also, when I go to turn on the ignition, sometimes, I get nothing. I wait a minute or two and then it starts. I think the first symptom was when I noticed about a month and a half ago, when I would turn the car off, the heater stayed on. I have been told that it could be the ignition switch. Any other theories?

anon132718
Post 35

i have a 62 pontiac. ok, as soon as i put the key in, it tries to start. it did that for a while and now the battery is starting to drain. however, i put an alarm on the car and it's not receiving any signal but my security light blinks. is my alarm interfering with my ignition switch?

anon123081
Post 34

my name is T. i am having the same problem as angel eyes. i have gotten a lot of things fixed on my car, all of the things you just named plus more. And just like you everyone who inspects my car is stumped! i don't know what to do. Any suggestions? I really need help! thanks

anon117980
Post 33

I have a 99 jeep grand cherokee and when i get in to start it, I turn the key and it doesn't start. it doesn't even act like it wants to turn over.

It makes no sound whatsoever and the gadgets go crazy and if i wait 10 minutes or longer, sometimes it will start back up. But, when it does this i can't operate anything -- the windows or anything. My husband thinks it's the engine switch.

anon104871
Post 32

Very helpful and informative article. thanks!

drick
Post 31

This is a very informative and detailed article about the ignition switch. It helped me a lot.

anon91794
Post 30

I have a 2006 chevy colorado. Randomly, maybe once a week, the anti theft system is activated somehow. Then, you have to pull the key and wait ten minutes before it'll start. Sometimes, I don't have ten minutes to wait.

Is there any way to deactivate it permanently? The dealer said their diagnostic machine shows nothing wrong.

anon83492
Post 29

i have a 1974 ford orion and i have no keys. where can i get some?

anon76324
Post 28

I have a 1989 Ford F-150 and I can't get it to start. Replaced the starter and tumbler because when I turn the key nothing happens and the key feels sloppy, will not go back to original position. Any thoughts?

anon67740
Post 27

hey i have a 01 chevy malibu and i can't get my key to switch to off.

anon67121
Post 26

This morning when I started my 95 Ford F150, the radio wasn't on. I continued to back out of my driveway and noticed that my ABS brake light was on, then my cruise control light kept flashing. When I went to roll down my window since my turn signal was not working, my windows would not work.

Now I was getting creeped out and thinking Christine- the possessed car! I turned the truck off, and when I restarted it, it was fine. The key did feel funny when I turned it.

anon63411
Post 25

I own a 2005 Chevy Colorado with almost the complete opposite problem from the previous poster. My Colorado has been known to turn on when no one is around and the key is not in the ignition.

It appears as if the key was turned into the power mode (radio, lights, wipers, etc.). The moment I open the door it usually shuts off, but on occasion I have to put the key back into the ignition, turn it on and off to reset it.

I have owned this truck since April 2009, and in this time the truck has done this about two or three times a week. I have taken it back to the dealer twice with no luck in finding the problem and to another independent shop with similar results.

My question is does this appear to be a bad ignition tumbler or is this a bigger problem? And has anyone else had a similar problem? Could this be a manufacturing problem? I have tried to get the dealer to replace the tumbler but they would not (at least not for free) since they did not see the problem. ~ Dan

anon57960
Post 24

I have a 2005 chevy cobalt, when I go to start my car it makes a noise like I'm holding the key too long, that is beginning to sound worse and worse. I got the starter replaced thinking that was the problem and I still have the same problem. Could it be something with the ignition switch? -Jrw

anon55335
Post 23

i noticed recently that when i drive my car to a certain point it turns off the sound system. also the car might turn off at some point. In addition i noticed that the lights on the dash board dim. what is the cause? is it the ignition?

anon53558
Post 22

We I go to start my car sometimes (mornings usually), I'll turn the key to "on and everything comes on (radio, lights, AC) but when I turn it to start everything goes off and it won't start. There are no noises and if i hold it in the start position for then it'll eventually start.

Doses that sound like the ignition switch?

anon50644
Post 21

Is it true that if you have too many keys on your key ring while the key is in the ignition, that it will make the ignition go bad? If so, how many is too many? I have a 2005 yukon.

anon44773
Post 20

i've got a 96 caprice classic that was running fine. one day i went to start it up but it didn't start. on the dash it said pass key fault -- something to do with anti-theft. i had the key checked out. it was fine, but the battery light still comes on. what's wrong with my car.

anon42098
Post 19

- AngelEyesz - any answer to your issue? I have the same going on with my 97 jeep. I can start it right up and run it as long as needed, but I can't restart it for 15-30 min after that. thanks- co-apline

kwiklip
Post 18

I asked this question and need to know if this answer is correct:

"I am having multiple issues that I think are related to the electrical system in my car. It needs to be jumped almost every time I start it, even though I have had the alternator and battery replaced. If I set the e-brake when I park, it will usually start the next time I go to start it. I notice that the fan/ac/defroster will be running 1-2 hours after I park, even while the car and the fan are both turned off. The fan will go off when I start the car. I have had it to 4-5 mechanics, with no success. A mechanic friend of mine said he though something was shorting and maybe the car had been in a flood. Any ideas?"

He responded that it could be due to water damage, but it might also be the ignition switch. After reading the above article, I'm not sure. What do you guys think?

anon38794
Post 17

I have a 2002 Mustang V6. I have an interesting problem where when I turn the key to just the accessories, the car will just start up automatically. When it starts like that, I hear a grinding noise when I shift into park or neutral. Does this have to do with the ignition?

anon33513
Post 16

I have run into the same problem as anon28420.

My 2006 Chevy Cobalt got stuck in the ACC position. I can turn the car on but it wouldn't let me take my key out. I have the bear minimum for the features. This also means no auto locks of keyless entry. Being in a neighborhood that's not safe I can't leave the car unlocked with the key in the ignition.

I managed to get the key out. Now the tumbler is still stuck on the ACC position and I can't put in the spare key. I can turn the car on with any key. Is there a simple fix or will I need to replace the key chamber? How much does this part cost? And should I be worried about the clock being left on?

lewiswhit11
Post 15

I have a 1999 ford taurus ohc. Yesterday car did not start. Got battery jumpstart 3 different times in 45 minutes by 3 different people. Car still not starting. After 30 more minutes car starts. Then in evening same thing happens. What is the reason? Please tell me. Car mechanic says "it is bad starter" Is it?.

anon31116
Post 14

*Help!!* My Jeep Cherokee 90 is cranking but not starting! What is it? And what do I do?

AngelEyesz
Post 13

Have a 1987 Chevrolet Cavalier Z24 2.8. motor initially it is starting/cranking, fine. the problems occur when the car is driven for a short or long distance. when I turn the ignition off it hesitates or won't start back up at all. i have to sit and wait for approximately 20-30 minutes b4 it starts back up. the same problem happens when the car is crunk up in stationary position. the car might start back up initially after you have driven it and turned the ignition off. if you immediately turn the ignition back on it but won't start back up if it sits for about 15-20 mins.

the car seems like when it has generated an extreme/excessive amount of heat somewhere in one of it's mechanical parts, it has to cool down b4 it starts up again, just my unprofessional guess i'm definitely not a mechanic, but I am the owner of the car for 15 yrs. Pleaseeeee ur help is very much appreciated and this is a list of things that have been replaced on the car so far:*oil pressure switch, fuel pump, fuel filter, ignition part and module.*

It was suggested that it could be the *starter motor.*

The starter motor initially cranks up fine but after it generates some heat it has to sit for about 30-35 mins b4 it starts again. My mechanic is stumped right now after replacing all the other parts. He's thinks it's not the starter motor. How can he be sure it's the starter motor when he did the basic check. What else can he do or can it be an electrical problem?

anon28750
Post 12

Can the ignition switch cause the car to stall?

anon28506
Post 11

Hi, I have a 2004 Saab 9-3 Arc, and about a week and a half ago my car alarm started going off randomly throughout the night. I called the dealership and they told me to go down to O'Reilly's and get the battery checked. I did and the battery was perfectly fine. *Then* two days later, at 1 o'clock in the morning, the alarm started going off again. It did this every 2 minutes until 9 o'clock in the morning until the battery *finally* died. (I didn't know how to unhook it). Of course all my neighbors were angry and the cops came 400 times. (embarrassing, I know.)

My husband is deployed and I feel like since I am a female, all the shops I take it to want to take advantage of me. I went to the dealership, and they checked it out all weekend and at first they tried to tell me the only thing wrong with it was the battery. I flipped out and told them that the battery was checked *two days* prior and there was nothing wrong with it. And my battery wouldn't have been dead if the *alarm* wasn't going off for 8 hours straight. But anyways, they decided I needed a new ignition switch. They put that in and charged me an arm and a leg. I finally got my car back today and the alarm has not gone off not once. I am just wondering if their being an ignition switch problem sounds legit as to why my car alarm was going nuts *or* did I just get taken for 300$? *Thanks.*

anon28420
Post 10

*has anyone had a problem like this?*

i have a 2000 malibu and my ignition switch went bad so i got a new one, well when i hooked up the new switch and after the anti theft system went off, what it does it won't let me turn the key to the *off* position so it forces me to leave it in the ACC which leaves my radio on and my tachometer.

i tried opening doors and all that does not work. what seems to work is when i unhook the battery so that the car has no electricity and once i hook it back up it will turn to the *off* pos and that only happened once so for the second time when i started the car and turned it off it won't let me turn the key to the *off* again.

cscarecrow
Post 9

i have a 2005 Chevy Colorado 5cyl. Every once in a while i have troubles starting it. Turn the key, let go of it & it keeps on like i'm holding the key too ling. It acts like it wants to start but won't ever turn over. i can wait 10min try again & it starts like nothing was wrong. I got aggravated & crawled under the truck, tapped on the fuel lines/pump, maybe there was a block some where. I've done this the last 2 times it acted up & the truck starts right up. Just this week my gas mileage has dropped drastically. i've gone 136 miles & used a 1/2 tank of gas. That is not right for my truck. Well i took my truck to the chevy people b/c it got worse this wk. They called to let me know it's my ignition switch. Parts & labor $200. One, does this sound like a ignition switch problem? Two, does my fuel ave anything to do w/ this if it is the switch? Being female i can't help but think i'm about to be screwed! Any ideas???

anon16301
Post 8

Posted by: anon7849

i recently purchased an older vehicle (1989 nissan pathfinder) and when the starter cranks the engine starts right up. sometimes it will start on the first turn of the key and sometimes it may take 20 turns of the key to start. i'm fairly confident that it is not the starter, but the electric switch. is it more likely that it is the switch and not the starter?

anon15329
Post 7

Dear Stig, connect the ignition wire of the alarm to the running lights from the tow vehicle, this will set the alarm whenever the vehicle is detached and prevent the alarm from going off every time you hit a bump while towing. I would suggest mounting a solar trickle charger to the roof of your trailer and connecting it to the battery to prevent the alarm from draining out the battery, which it probably would over several weeks. Good luck with your project.

anon7880
Post 6

ekanayaka, you shouldn't keep the key in the "on" position because any lights, radio, guages, etc. would be run off of the battery. When the car is on and the engine is running, all of your electrical equipment is run off of the alternator. Seven minutes is no big deal though. As long as you can turn your car back on, the alternator will recharge the battery.

anon7849
Post 5

i recently purchased an older vehicle (1989 nissan pathfinder) and when the starter cranks the engine starts right up. sometimes it will start on the first turn of the key and sometimes it may take 20 turns of the key to start. i'm fairly confident that it is not the starter, but the electric switch. is it more likely that it is the switch and not the starter?

Mary in PA

anon6585
Post 4

Very useful article...thanks!

anon6115
Post 3

Thank you. I am having trouble with a key working in my ignition...and now I know what's going on. Thanks again!

Pauk

ekanayaka
Post 2

Why are we warned not to keep the key in the "ignition on" position when the engine is not running lest the battery be discharged and the ignition damaged? How long will it take for this to happen (minutes ? hours ?). I have a brand new Toyota Yaris and today I switched to the "on" position when parked to pull down the electrically operated windows and forgot to switch off for about 7 minutes!! Should I worry ??? - Please reassure if possible !

Dr. Asoka Ekanayaka

stig
Post 1

if i was to install a car alarm on my trailer which has no engine, only a 12-volt battery... where would i connect the ignition wire lead of the alarm?

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