01 celica gt s, viper 5901 remote start

yes, if you open your door and close it back up without resetting reservation or remote starting the car it will reset reservation. if the car is entered and the car is put in gear it wouldn't be safe to remote start. if viper didn't make it reset when the door pin is flashed it would cause a lot of liability problems for them.

Right but if the car is in gear the neutral safety switch would prevent it from starting.

I don't bother with the neutral safety wire, usually it's a pain to locate and it isn't necessary. like already said, the viper resets reservation in the event of the door opening and closing while in reservation. if you do what you should when you park the car you'll never have a problem. it's not complicated. put the car in neutral, put on the e brake, make sure you aren't on the pedals and pull the key, then get out. that's all. once you've done it two times you'll realize how simple it is.

I'd rather bother with a neutral safety wire once than the reservation thing 1000s of times. Plus I don't want to have to start my car up just if I need to get back inside it for 20 seconds.

The problem with connecting to the neutral safety wire on your car, proximity, is that it most likely doesn't exist. Generally the only switch at all on a manual transmission is for the reverse lights, the manufacturer considering the clutch switch sufficient for preventing starts while in gear. It's not impossible that such a switch is present for neutral(IIRC Mazdas have one) but it's generally very unlikely. If you had a shop manual for your car that showed one present and gave you wire colors, that would eliminate the need to use the 689M or "reservation mode". For more on this subject, check this out.C Renner's Auto Electronix

My service is cheap, quick, and good - pick any two