Red Start Button
race car inspired big red push button starter on the new Honda S2000 I was
recently reading about, made me think of the big red button in the middle
of my dash. What the heck was it for anyway? It didn't operate the roof,
spray a smoke screen or eject my passenger … so what was it good for? Oh
yeah, the hazard lights. Good thinking, easy quick access in case of an
emergency … Let me see, while threshold braking, downshifting and slalom
maneuvering through a maze of destruction and mayhem, take one hand off
the controls and apply the hazard lights. Yeah, right. Then I figured: who
would put a great big red button in the middle of my dash if it weren't
really meant as a starter? I could always wire my hazard lights someplace
more convenient, like beside the steering wheel perhaps?!!!! You can stop
worrying about being sucked into a black hole driving home from work.
My first step was hiring our clubs resident Electronics Ph.D., Grant McGibney to help me figure out how to wire it up. The solution: a simple high current relay that would put power to the starter via pushing (a releasing) big red Hazard button. Now before I go on, I must warn any readers with newer cars (mine's a 90) or US vehicles, that the wiring may be somewhat different and you should fully review your shop/enthusiasts manual and test all circuits first before following any of my directions. So here it goes …
The ignition switch during starting, takes power away from IG2 (Ignition 2 circuit) temporarily while it applies power (Battery or B2) to the starter circuit (ST). IG2 runs some accessories when you turn the switch to "ON" like the wipers and daytime running lights. So basically, that's all we have to do with the starter button! Here's the circuit:
We take IG2 from the ignition switch, terminate it on the relay so it is normally closed. Disconnect the starter wire "ST" from the ignition switch and apply it to the "normally open" terminal. We also need to take IG2 and power the relay from it (terminal A) with terminal B connected to our push button switch. Pushing the starter button when IG2 has Battery (switch at "ON") will operate the relay, disconnecting IG2 and sending power to the starter. Simple right?
The next step is finding the right relay and actually making these connections. The relay I bought is a 30Amp dual pole, single throw (5 terminal) normally closed unit made by Siemens (part number VF4-45F11). I bought it from Richey Electronics in Calgary ph. 403-259-6817. Then you'll need to refer to your wiring diagram to determine what wires are what at your ignition switch. My wiring diagram is in section "F"(Fuel and Emission Control System) - don't ask why - and shows the following colors for the wires of interest:
IG2 Black with Red stripe
ST Black with Blue stripe
Make all connections as per the circuit diagram above but be aware of the following hints:
1 Make sure the batter is disconnected while you do all of your wiring (DC Power hurts)
2 The wires leading from the ignition switch are big (gauge 12 at least) and need fairly good size connectors.
3 I recommend accessing the ignition wires low in the cable harness instead of right at the switch like I did. There's very little slack available right near the switch.
The final step is "delatching" the latch mechanism on the hazard light. This is fun, especially since both the hazard switch and headlight lift switch are in the same box! After you yank your dash apart, you'll find you can remove the whole switch "box" with a couple of screws. Be careful as you pop this guy apart as the little wire latches and spring usually make a go for it. There's a tiny spring and small wire latch that once you remove and reassemble the box, the hazard button won't latch any more and instantly becomes the perfect starter button. On my car the hazard circuit was a single orange wire that connects under the dash to the "hazard flasher". It's pretty easy to find if you put the hazards on and hunt for the noise.
Once your done, your car will have a cool "race car" red starter button. Eat your heart out S2000!