There are 2 different styles of MkIII keys. I forget if it's 90 or 91 when Toyota changed them but those newer keys are longer, have a groove in them, and are actually 2-sided tumblers iirc so they're a LOT harder to get into even with a ton of Toyota keys... The older key type on every year before that however is far less complex and it's suprising how many other Toyota vehicles they open, not just MkIII's and vice versa...
My buddy's wife's 88 Camry key opened one of my 87 or 88 MkIII's, one of my 87 or 88 MkIII keys opened and started his 89T, and a few of us could open other Supras with our keys. My Supra key that her Camry key opened did NOT work in her Camry at all and her Camry key would not start my Supra.
One time in a junkyard they had a clean 89T that was locked and between the 6 of us that were there and all our Toyota keys on our keyrings one of them worked in the passenger door.
None of our 91-92 keys ever opened other Supras that we know of, including each other's...
As the buddrick said, the stock system is automatically "passive arming" (insurance discount if you've got comp & collision or theft coverage!!!) and it will go off if it's already locked/armed and someone tries to reach in and unlock the doors or open the hood or hatch and it will kill your starter too until you disarm/reset the system with the key in the door turned to unlock/disarm iirc.
The 86.5 and any 1986 built 87's will not arm with the key so you can lock them with the key and the system will NOT arm (great for extending battery life when parked if you don't need the alarm) BUT if you lock them with the door lock button and hold the handle up to close the door they WILL automatically arm.
Typically if the stock system goes off at random (not when you try to unlock a door with the key!) then someone's jacked with the switches on the lock cylinders or one has come off and isn't in the neutral position anymore. My 2nd MkIII had them both removed from, the locks, turned to one extreme, taped down to the harness, and it went off and killed the starter signal at random 'till I reset and reattached them both and the problem went away. My 89T wouldn't disarm from the driver's door and the switch was bad but it was still mounted properly and never caused falsing or starter kill problems at all. I finally grabbed one out of a junkyard and it solved that problem completely.
I've lived in Houston with a rare factory 2-Tone Blue MkIII for 3 years back when the MkIV's were brand new and even the oldest MkIII's were still less than 10 years old, then the Greater New Orleans and Mississippi Gulf Coast region since 1997, never had a garage, parked on the street in the New Orleans french quarter regularly overnights, and noone ever really bothered my 2-tone blue 87 Hardtop, Dark Blue Pearl Targa 89T Super Red Sunroof 92T, or even my 94TT or 98TT MkIV's... Someone tore up the locks on my 92T once at my apartment complex in the New Orleans area but they also hit every car in the parking lot and got 2 of them open and my Supra wasn't one of the ones they got into...
It's not the best system but it's certainly not the worst thing out there.
Plus it NEVER falses in a thunderstorm or when someone's car stereo booms too much because there's no type of shock sensor on the stock TDS system at all.
If you're lucky enough to have gotten the 91-92 MkIII Factory TDS-E Remote Entry Kit Upgrade you also got a "Horn Defeat" switch by the defrost switch and a "Glass Breakage Sensor" built in which I happen to like. Gives you glass disturbance triggering instead of shock triggering so it never falses and still gives you protection if someone tries to break your windows... I lost my TDS-E that I had custom retro-fitted into my 1986 built 87 back in like 1995 to hurricane Katrina.
Note that not all "dealer" remote kits were the real TDS-E kit so just because you have a remote doesn't mean you were lucky enough to get the TDS-E Kit and the crappy dealet installed remotes have a shock sensor but it's disabled. If your remote doesn't have the Totota name/logo on it somewhere and/or you don't have the "Horn Defeat" switch then you don't have TDS-E. If you have the Horn Defeat Switch on your dash and you don't have a remote, just go to your dealer and get the remote or sell me your TDS-E Kit and I'll talk you through the simple plug-n-play removal of it anytime...
If you live in a shady area it's something to consider doing a fuel pump kill switch or something like that but if your area is safe and crime is low I really wouldn't be concerned as the stock system is probably far more than adequate even with such a "rare" car...
My buddy's wife's 88 Camry key opened one of my 87 or 88 MkIII's, one of my 87 or 88 MkIII keys opened and started his 89T, and a few of us could open other Supras with our keys. My Supra key that her Camry key opened did NOT work in her Camry at all and her Camry key would not start my Supra.
One time in a junkyard they had a clean 89T that was locked and between the 6 of us that were there and all our Toyota keys on our keyrings one of them worked in the passenger door.
None of our 91-92 keys ever opened other Supras that we know of, including each other's...
As the buddrick said, the stock system is automatically "passive arming" (insurance discount if you've got comp & collision or theft coverage!!!) and it will go off if it's already locked/armed and someone tries to reach in and unlock the doors or open the hood or hatch and it will kill your starter too until you disarm/reset the system with the key in the door turned to unlock/disarm iirc.
The 86.5 and any 1986 built 87's will not arm with the key so you can lock them with the key and the system will NOT arm (great for extending battery life when parked if you don't need the alarm) BUT if you lock them with the door lock button and hold the handle up to close the door they WILL automatically arm.
Typically if the stock system goes off at random (not when you try to unlock a door with the key!) then someone's jacked with the switches on the lock cylinders or one has come off and isn't in the neutral position anymore. My 2nd MkIII had them both removed from, the locks, turned to one extreme, taped down to the harness, and it went off and killed the starter signal at random 'till I reset and reattached them both and the problem went away. My 89T wouldn't disarm from the driver's door and the switch was bad but it was still mounted properly and never caused falsing or starter kill problems at all. I finally grabbed one out of a junkyard and it solved that problem completely.
I've lived in Houston with a rare factory 2-Tone Blue MkIII for 3 years back when the MkIV's were brand new and even the oldest MkIII's were still less than 10 years old, then the Greater New Orleans and Mississippi Gulf Coast region since 1997, never had a garage, parked on the street in the New Orleans french quarter regularly overnights, and noone ever really bothered my 2-tone blue 87 Hardtop, Dark Blue Pearl Targa 89T Super Red Sunroof 92T, or even my 94TT or 98TT MkIV's... Someone tore up the locks on my 92T once at my apartment complex in the New Orleans area but they also hit every car in the parking lot and got 2 of them open and my Supra wasn't one of the ones they got into...
It's not the best system but it's certainly not the worst thing out there.
Plus it NEVER falses in a thunderstorm or when someone's car stereo booms too much because there's no type of shock sensor on the stock TDS system at all.
If you're lucky enough to have gotten the 91-92 MkIII Factory TDS-E Remote Entry Kit Upgrade you also got a "Horn Defeat" switch by the defrost switch and a "Glass Breakage Sensor" built in which I happen to like. Gives you glass disturbance triggering instead of shock triggering so it never falses and still gives you protection if someone tries to break your windows... I lost my TDS-E that I had custom retro-fitted into my 1986 built 87 back in like 1995 to hurricane Katrina.
Note that not all "dealer" remote kits were the real TDS-E kit so just because you have a remote doesn't mean you were lucky enough to get the TDS-E Kit and the crappy dealet installed remotes have a shock sensor but it's disabled. If your remote doesn't have the Totota name/logo on it somewhere and/or you don't have the "Horn Defeat" switch then you don't have TDS-E. If you have the Horn Defeat Switch on your dash and you don't have a remote, just go to your dealer and get the remote or sell me your TDS-E Kit and I'll talk you through the simple plug-n-play removal of it anytime...
If you live in a shady area it's something to consider doing a fuel pump kill switch or something like that but if your area is safe and crime is low I really wouldn't be concerned as the stock system is probably far more than adequate even with such a "rare" car...
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