Build Your Own Turbo Timer

Hate waiting for your car to cool down? So did I, and I didn't want to pay over $100 for a simple timer, so I built my own. Disclaimer: DON'T try this unless you have a good knowlegde of electronics, these instructions are meant as a guide. Make sure you know what your doing at each step. The wiring diagrams in the Haynes or similar manual are a necessity, and so is the timer circuit from Radio Shack's Engineer's Mini-Notebook (cat# 62-5010) page 9. Read all of my instructions before starting and check and double check and test everything as you go. If you have a 12V power supply (or 12V AC/DC adapter) you can test the timer and relay before putting them in the car.

Part 1: Build your own Turbo Timer (3-4 hours)

How it works:

While the car is running, you push the new button that you mount on your dash. A little red LED starts flashing indicating that the timer is on. The timer turns on the relay which passes power straight from the B wire to the A and IG wires. Thus, when you remove the key the car keeps running until the timing cycle finishes. Then the timer turns off power to the relay, and the relay shuts, turning off the power to the engine.

Building the Turbo Timer

Buy all the parts shown on the diagram on page 9, as well as a push button (interupt type), flashing LED, 15A relay, and relay socket (this way if the relay burns out, you can just pull it and replace it. No need to resolder anything to the relay. You should also have the Haynes manual for the ignition wiring diagrams.

I used a 220K + 470K restistor in series to give 690K for R1, and I think for C1 I used two 100uF capacitors. You can play around with these two parts to change the length of the timing cycle (or use an adjustable resistor for R1 to make the time cycle adjustable). My timer runs for 2 minutes 20 seconds.

Nissan says that about 12A runs through the ignition, so I used a 15A relay. Once you've built the timer, test it before you put it in the car. Also make sure the wire you use from the ignition to the relay and back is at least as thick as the existing ignition wiring.

DISCONNECT THE NEGATIVE BATTERY CABLE SO YOU DON’T SHORT ANYTHING OUT!

To wire it in, you need to leave the original ignition wiring in tact, but tap into the B (battery, color: W/L), IG (ignition, color: B/W) and A (accessory, color: W/Pu) wires and these will run to the relay. Make sure you use thick wires here. They should be the same thickness as the B, IG, and A wires. My relay had contacts like this:

1 2
3 4
5 6
A B

A+B are for the power to the relay from the timer circuit. The B wire from the ignition should connect to both contacts 5 + 6 on the relay. The IG connects to 3, and A to 4.

I put a nice red button on the dash beside the toggle switch for the dash brightness. I also put in a flashing LED to indicate that the timer is turned on. The LED is connected to pins A and B of the relay. You have to use a resistor with the LED so you don't burn it out. I think I used 1M ohm.

Connect the timer, but don't connect the relay to the ignition until you verify that it works properly. Try it out, and double check all you wiring. Once your sure everything is correct, disconect the negative from the battery until you get it wired in to the ignition, then reconect the battery. Start the car, press the button, take out the key, and the car should stay running for about 2 minutes!

Part 2: Alarm re-wiring (2 hours)

DISCONECT THE NEGATIVE TERMINAL ON THE BATTERY!

To make the factory alarm arm after you take out the key and close and lock the doors requires a second relay.  The A+B contacts connect to the A+B contacts on the timer relay (so both relays turn on together).

Now you need to take off the kick plate that covers the computer and the plastic door sill, and pull the carpet back.  It will also help if you pull out the glove box and heater/radio console.  Now find the Yellow wire with the green stripe in the bundle of wires that runs along the door sill to under the passenger seat.  Cut it and run a wire from each half back to the timer under the dash.  Connect these two wires to contacts 1 and 3 on the relay (doesn’t matter which wire you connect to which one).

Now find the blue connector in behind the computer and disconnect it.  Cut the black wire with the white stripe, and run a wire from each half to the new relay.  Connect these two wires to contacts 2 and 4 on the relay (again, doesn’t matter which one connects to which).

Solder all your connections, tape them up real good, re-connect the battery, and test it out!

Start the car, press the button to turn the timer on.  When you open the door, the alarm light should start flashing.  Lock and close the doors and the light should go on solid.  After 30 seconds, the light will go out, and the alarm will be armed!

Put everything back together.  Done!

Email me with Questions!