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Need to prevent my car from starting

I know, sounds weird right? I share my car with my grandfather, he’s 85 years old. His age is starting to catch up to him and I have serious concerns about his ability to safely drive… oh, and did I mention he also drinks A LOT! I worry about his safety and for every other driver on the road when he’s behind the wheel. And “no”, I’m not going to take his keys away from him because he’ll make my life miserable.

As a temporary solution I’ve been disconnecting the cables to my car’s battery. My fear is that disconnecting the cable will prematurely wear the battery down. I had both cables disconnected over night and when I went to start the next day, it didn’t turn over right way when previously it’s been running fine.

So, what’s my question? Is there a fuse I can pull or some other “easy” thing I can do that will prevent the car from starting so my Grandfather doesn’t (seriously) kill himself or someone else on the road from either poor reflexes or DWI. Again, I will not take his keys away.

1998 Saturn SL1


disconnecting the battery cable is best, anything else and he may crank the engine until the battery dies. This way, nothing happens - just make sure you install them TIGHT when you put them back.

I would look into having a starter interrupt switch installed. hide the switch well, and it shouldn’t cost you much, but takes 2 seconds to disable/enable the car (in case of emergency, you want to be mucking with cables?)

Thanks Realbinky! That sounds like a potentially great solution (starter interrupt switch); I’ve thought about the “in case of emergency” problem as well. Do you know where I can go to find out more about an SIS? And how easy are they to install? I’ve searched around Google some but the sites seem to be devoted to total gearheads and outside of my area of experience so I have no idea what they’re talking about. Any advice?

Install a battery disconnect switch in line with the positive battery cable. Disconnect the battery by turning the switch instead of disconnecting the cables. Reconnect the same way. A real time saver in your case.

Disconnecting the cable(s) will not cause the battery to drain faster. There is ZERO drain on a disconnected battery.

I’m a little confused. If you’re pulling the battery cable, doesn’t he know that you’ve done something to the car, which would upset him as much as taking away the keys?

Perhaps you’d want a hidden switch that kills the power to the fuel pump so that the car will turn over normally but not start. Then you could say that the car just acts up sometimes. A shop that sells aftermarket alarms could probably help you with something like this or give you some other ideas.

If the battery cable approach doesn’t upset him, then a simpler way to do this is using a knob at the battery terminal that you remove when you don’t want the car to be started. Search Amazon for “battery disconnect knob” for some examples of what I mean.

By the way, you mentioned that you’re disconnecting both cables now. You only need to do one, which should be the black one for safety reasons. (If you keep disconnecting both, then disconnect the black one first and reconnect the black one last for safety reasons.) Speaking of safety, it’s always a good idea to use safety goggles when working with a battery. At least one member here has had a battery blow up on him.

For an extra layer of safety, consider chocking a wheel with a small black wheel chock that won’t be noticeable.

Thanks for making the effort to keep him off the road!


Yeah I hear you. I think you have to think long and hard about taking someone’s keys away. Had the same issue with my 89 year old dad but he passed his driver’s test and the insurance company had no proble so I thought who was I to do anything about it?

You can pull the ECM/ignition/computer fuse. That will allow it to crank but not start. After my son’s car was stolen and recovered, we put in a hidden fuel cut-off switch. Same way, cranks so they don’t think anything is wrong, but won’t start.

When he doesn’t drink he has very slight dementia so a lot of things can be explained away, like the car not starting because of the cables. He’s not persistent enough to pop the hood as long as he can ask me what the problem is; and I divert the answer and promise to have the car looked at. Then he drinks. Then he forgets that the car wasn’t working earlier. Rinse and repeat.

Thanks for cluing me into the dis/re-connect order, I was going Red/Black, then reconnect with black/red. I think I’ll just stick with the black cable only until I can look into either the fuse, battery disconnector knob, or fuel cut off switch.

Thanks guys. Aside from saving lives he’s been this is going to save me from stress overload. :slight_smile:

Many GM cars have a fuse labeled “crank” in the interior fuse panel. If you pull that one, it will interrupt power to the starter relay, not allowing the starter to engage. Everything else will behave normally, but the engine will not crank.

I would take his keys while he was on a good bender and alter the ignition key with a metal file until it no longer worked to turn the ignition switch. He sooner or later is going to figure out the battery cable thing, and even if you pull a fuse, if you are able to the get car to run every day, while he never can. Even severe Alzheimer patients have moments of clarity.
The “worn” ignition key can become the thing you keep promising to get looked at until he gets drunk and forgets. That way you don’t have to disable the car every day.
Also, if you have the remote keyless entry, just have the battery on his set of keys removed and lock the doors every day( I’m unsure if you also have a doorlock accessible by the key, but again, deform his key). Make it as hard as you can for him to get access to the car.
You might also just lose his keys for him (which he would hopefully think is his own fault) and keep promising replacement and never delivering.

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We took the keys(and car) away from my Father-in-law (85). A drinker also. The final straw was one afternoon he stopped by the middle school to give my nephew a ride home (no problem he’s done this many times before). But he had stopped at the American Legion before and had about 6 beers. My sister-in-law was home when he came stumbling in with his grandson. We had a family meeting and decided he just couldn’t be trusted with the car anymore…It’s a tough decision, but it HAD to be made…For the safety of him and more importantly his grandkids and all other drivers on the road with him.

And it’s caused a lot of problems in the family. We now have to take turns driving them around…my wife or daughter have to drive to Upstate NY once a month for a weekend to share in the responsibility of doing errands…It’s a burden on everyone…but it HAS to be done.

If you remove the red cable first, if your screwdriver slips while doing that and touches anything metal near the battery, there’s a good chance you’ll cause a short circuit and make a huge spark. That won’t happen if you remove the black cable first.

I didn’t notice any labeled “crank”. But there were a couple that caught my attention, not sure if they’re the equivalent(??). Two labeled “IGN” and one “Turn” (although now that I think about it, the latter is probably the turn signal). Would either of those IGNs be what I’m after? Interior is definitely easier than popping the hood if it accomplishes the same thing.

Most likely…IGN typically stands for “Ignition”, although which one serves which specific purpose is a guess at this point. Try them one at a time, see what happens. You won’t hurt anything either way. It’ll either do what you’re after, or not, as the case may be. Yes, Turn would be turn signals.

Put any extra fuses you have in the trunk, too. Out of the way, but still available in case you need one.

…and thanks for helping to keep the roads safe for us and our kids.

When my mother got to the point in her dementia that she shouldn’t be driving, I didn’t have the heart to take her keys away, plus I worried that I would not get all the copies of the keys. What I did was to pull the starter relay from the fuse panel. That way the computer memory was not lost. Everything on the car worked except the starter motor. No extra wiring was involved - just pull the relay with no tools needed. I would then plug the starter relay into an unused realy socket so I knew where it was all the time. This worked for me. Only one time did Mom complain that her car wouldn’t start.

Just tell him the deal… stop the passive aggressive sneaking tricking, it’s really not nice… he’s a man, treat him like one.

More than likely, he is a dead man, or is no longer driving at the age of 94.
Did you not see the date of the original post?

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Well , Daniel - Welcome . But since this thread is 9 years old I doubt if the problem still exists .

Also I guess you have never been in a position or knew someone who had to make the difficult decision to take away the keys from someone.

My aunt used to think her age was the speed limit. She worked well into her 80s, and drove there herself. Part of the issue is how the grandparent would take the loss of the keys. My aunt wasn’t too bad, but others can go ballistic.

After my aunt retired, her daughter and grandchildren tried to keep the keys away from her, but sometimes she found them. Under no circumstances would they ride with her. They always drove, or would not get into the car. It wasn’t easy, but they did keep the keys away from her for the last six years of her life.

I like that idea, Though one would hope after you can’t have a drink until we stop talking because you need to stop driving. Setting up an uber alternative for him he might enjoy! Carp fooled by another old thread. Maybe it is relevant to someone I hope.

As a former pro in the car alarm / remote start / stereo industry that is no more… What you are trying to accomplish is rather easy…

Just pull the starter relay… or… install a switch that supplies said relay with power to pole 86… 85 is the ground usually… but actually a switch in either wire to either pole will accomplish the same exact thing. It will disable the relay…and prevent the starter motor from engaging.

This will only be effective on an automatic transmission however…if its a manual he could pop start it with the key turned on…if he was really feisty about it.

If you need to disable deeper…that can be arranged. I’ve done just about anything you could imagine.

My fav technique was to hide the switch to the kill device in plain sight… Go to a junkyard and obtain say another rear defroster switch…or hell…use the existing defroster switch…as the starter kill. I could go more James Bond on you but I’m sure just cutting power to the starter relay will accomplish what you want to do.