| keyless entry system to provide the start-pulse to the start system. Entry system had a timeout pin that was suppose to light a entry dome light for 30 seconds. I inserted an automotive rated relay in to the SUVs EFI power circuit. The EFI relay in turn was controlled by a pulsed latching relay. This is just a regular relay wired to stay closed as long as power is applied (ie, ignition key is turned on) - when power is taken away the relay resets to off. So here's how it worked -- press the keyless entry and a 30 sec 12 volt signal pulls in the EFI controller (latching) relay. That relay won't remain latched after the 30 sec. 12 volt signal times out unless the ignition key has been turned. Once SUV was turned off -- everything resets. This approach was simple. Pretty easy to substitute the keyless entry unit with a (hidden) push button activated 30 sec. timer circuit that supplies the pulse. Here's a place that shows how to rig up a relay for latching:
CLICK HERE 
Circuit works like this: Trigger button causes the relay's coil to power up, pulling in the contacts. Once contact is made VS power is supplied to the relay's coil so when the Trigger button is released relay stays latched closed. Pushing the reset button breaks the power line and relay resets. Removing VS power (ie., car's ignition switch) would do the same thing. DEVICE in the picture is where the 2nd relay used to power the EFI or Fuel Pump circuit would be placed. Replace the Trigger switch with a 30 sec. +12v pulse and you've got the whole thing. Here's a simple circuit that can supply that type of pulse: Pulse Timed Circuit
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