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Hey looking for some input on a security relay for a remote start in a 5MT. I would like to get my remote start unit installed in my 5MT but do not want to do it without a failsafe where it cant start if its in gear. Now i was going to put a relay between the remote start starter wire so that it would have to be closed to work. I was then going to control the relay with the neutral switch.

The problem is the neutral switch wire running into the ecu only gives me ~10v in neutral and .2-.4v in any gear. This isnt enough to turn on a regular automotive 12v relay. Is this wire supposed to be 12v and i have some decaying wire causing the voltage drop?

Does anyone know where i can find a 10v coil relay that can handle the amperage of the starter wire from my remote unit?

I think the voltage you're seeing is probably fine.....those switches are a little funky.

You may need some sort of electronic device/circuit to monitor voltage of the switch, and when that circuit detects that the car is in neutral, it will send 12v to the relay you want to use.

Maybe Vikash or one of the other electronic guys could help.

Yeah thats what i was thinking. A logic switch or something, its just been a while since highschool electronics. Im also trying to think of a way to make it so it only will close with the remote start unit on too. Then the relay wouldnt be clicking every time i shift while driving. Only thing i can come up with is the remote start unit has a relay control output (+ and - wires) were the logic circuit would only close the relay if that output were closed AND the neutral switch is providing voltage.
Any ideas are much appreciated.

I don't think you want to do it this way; starter relays have to deal with a lot of inrush current so they can be expensive, and if you simply open the starter circuit you could end up upsetting the remote starter unit.

You can wire the neutral switch to the remote starter's hood pin input. I described how to do it in an earlier thread; search for it.

vrg3 wrote:You can wire the neutral switch to the remote starter's hood pin input. I described how to do it in an earlier thread; search for it.

This is how I do it. I do nothing but install Astrostarts during the winter months. Most cars don't have this as an option, though, and in that case we use a "manual transmission interface" module that needs to be set everytime you exit the vehicle if you plan on remote starting the next time you want to go somewhere. That piece is pretty much Astrostart specific, though you may be able to find something similar.

Yeah i should have figured there was a much easier way to wire up the neutral switch. Got everything hooked up last night and works great, thanks Vikash.

Any chance anyone can give me any more info on why the ECU has the neutral switch input when it doesnt seem to affect anything? Also what are its states? It appears the switch is closed when in neutral and open under any other condition. Does this switch ground out? I guess im confused as to why the hood pin input which looks for ground would work with the neutral switch which i show voltage on.

The ECU does change its ignition timing control algorithm when the transmission is out of gear; use my scantool or something and watch. I don't know exactly why, but it fixes timing at 15 degrees BTDC when you're out of gear.

The neutral switch is open in neutral and closed in gear; the hood pin switch is open when the hood is down and closed when the hood is up. Both are connected between the relevant control module and ground.

The reason you read a positive voltage on the neutral switch wire when you're in neutral is that the ECU pulls the signal up weakly. When the switch closes the circuit it pulls the signal down to ground. The remote starter actually does the same thing with the signal; the diodes isolate the two circuits from each other.