The Cybergenica Blog

TGIM – How to Hotwire a BMW 540i

Another glorious week begins, well not really, it’s still the weekend however since I have an epic announcement to make, why not share it with you all.

bmw-emblemAs some of you know our bimmer has been on the IR list for 2 weeks since falling to the infamous BMW Ignition Key Syndrome. The defective parts, and there are a few, puzzle the most seasoned mechanic minds.

But not mine…

After more than 2 weeks of trouble shooting, reading online forums and talking to mechanics, I finally broke down today and ventured down a desperate road, to hot wire my BMW 540i and drive it at any cost…

Powered by my father’s genes, who’s been a mechanic all my life of 44 years, I ventured down the lonely road leading to the ghost town called Hotwiring, FL. (In plain English I decided not to wait for the replacement BMW ignition part, instead I endeavored to start the car myself using a paper clip – Read on, it gets funny at some point :)

The previous day in a 5 minute phone conversation my dad revealed the basic concept behind most cars’ ignition switches. Typically a simple plastic cube with 4 wires connected to it, and also a hole on one side in which fits the metal ignition pin spun by the car key as you engage and start your car, but let’s stick to the 4 wires.

“The big thick red wire is juice straight from the car’s battery” he shouts. He’s hard of hearing you see. “You want to take power from the big red wire and spread it to both the main electrical wire and, for only a few seconds the starter wire also.”

Those 2 other thick wires are one for the main/power (lights to the dash and power throughout vehicle) and the other wire goes to the car’s starter motor. This wire should only have “juice” when the car is not running.

There’s also a small wire to tell the switch the car’s engine is running which normally automatically cuts off juice to the starter motor.

Simple right?

Wrong… The BMW doesn’t have 4 wires in the switch, it has ELEVEN!!!

bmw 540i ignition switch 1997 1993 1994 1995 1996 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008

With the basics in mind, I tested each wire for “juice” and found most of the thick ones had power except for the brown/yellow wire (bottom right, only wire with yellow in it, can’t miss it!).

Since I already had juice throughout the dash, instrument panel and accessories from the ignition barrel which was stuck in “on” mode, to start the car I simply used a paper clip.

I twisted the paper clip which I then held with insulated pliers, connecting a “powered” green wire to my brown/yellow starter wire. Oh by the way, for liability purposes, my attorney tells me I have to WARN YOU this paper clip method is untested and unapproved by BMW, this method is not recommended, because it’s unsafe and can kill you, 2 or 3 times over in too many ways to list here, such as having your nose punched through the back of your head when the TNT powered air bag explodes in your face while holding your little paper clip, all because you triggered a spark on the wrong lead. Seriously if you are desperate enough to try this, wear protective goggles and I strongly recommend a mouthpiece and a thick coat of Vaseline on any exposed section of the head, neck, arms etc. :)

bmw 540i ignition switch 1997

To my own amazement, the car cranked and started. I was finally able to hear and feel the rumbling of the V8 engine. PRAISE GOD ALMIGHTY!!!

I drove around the neighborhood before taking the ignition switch apart, fiddled with it spinning the selector with a flat head screwdriver simulating the pin/key turning. It clicked! I then put the switch back and voila! It’s a Miracle! The ignition now works great!

Far more labor intensive than my typical work day, today’s endeavor and tremendous success proved once again that through faith, I can do all things through Christ.

PS I saved over $1,200.00 in repairs by doing the work myself, and didn’t even wait 4-6 weeks for a $85 replacement part to get here by boat from Germany…

PSS What actually happened? When I turned off the ignition that day I did so with too much velocity for the old plastic & metal part assembly. While I turned the key (and metal pin) counter clockwise to cut off the ignition and stop the engine, the selector inside the ignition switch did not spin backwards the way it should have.

Therefore the ignition switch got stuck in the wrong mode, the “on” mode which meant the switch distributed power in this “on” mode feeding continuous power to the accessories and dash. Once the selector inside the plastic switch was spun backwards to match the key mode, turning off the ignition was back to normal. So is starting the Bimmer, back to it’s normal ultimateness. :)

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