locksmith wanting advice on trunk releas

Hello, I run a small locksmithing shop in southern KY. I get call's about once a week for keys locked into a trunk. If anyone has done this type of work, they now how extremely difficult it is to pick a trunk lock. I was called out last week for a '93 Caddy Deville and attempted to bypass the button by applying negative voltage to both terminals of the switch with no luck. I finally picked the trunk lock (those sidebars are tough). Last night I was agian called for a lockout on a '04 chrysler sebring convertible so going through the back seat was out, and I couldn't get the locked picked. I agian tried applying voltage to the terminals on the button, first negative and then positive. When applying the postive I got a spark on one of the terminals so I figured that it had negative voltage on that side of the switch.
     My question is, is there a relay under the hood that holds power from going to the trunk solenoid? Is there a module that requires a low input voltage and inturn sends a higher voltage to the solenoid. Last question, what is a trunk pin?

The easy one first: A typical trunk pin is a simple switch that activates when the trunk is opened. Here is one example.

Now, to the trunk popping via jumpers. I would strongly recommend a quick stop to this practice. A large majority of newer vehicles no longer use a straight negative or positive to activate trunk release. Most now use a data/multiplex system of one type or another that requires a specific resistance/information on the data line that will activate a relay/solenoid/device and pop the trunk. If you were to apply ground or +12V to the data wire it can cause irreparable harm to the body control module (BCM) and cost you a significant amount of money to repair the vehicle. As far as the 'under hood trunk relay' is concerned, although you may find some vehicles that have this, most will be part of the BCM now.

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Installer, IT support, and FFL. I need less hobbies.

Thanks for the heads up. What about applying voltage to the accessory wires? Not trying to force the subject, just wondering.

A big issue with trying to get the trunk release to activate is every manufacturer does it differently. The Sebring conv. runs the release thru the BCM and even tho the switch itself is a simple negative pulse the BCM won't allow it to work unless the key is on. Your only choice to make this work would be to know the exact wire traveling to the trunk and cut it to apply voltage(many are 5 wire type so you can't just apply voltage without cutting the wire or you will do damage).

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Mike M2
Tech Manager
CS Dealer Services

I've done the same thing myself a few times, both as a former tow truck driver providing lockout service, and when a girlfriend was using my car and locked the keys in the trunk. (I talked one of her college friends through it over the phone.)

If you go to techservices.audiovox.com, you can sign up for an account, and then you can look up the trunk-release information for each car. It's not guaranteed to be 100% accurate, but it's a start.

Twelvoltz is right that all cars are different.

The "5 wire" setup he mentioned is common to Toyotas. It's a positive trigger to open the trunk, but the wire also rests at ground. So the wire has to be interrupted (we use a relay) and positive applied only to the side of the wire going to the trunk.

On the Sebring convertible, as he said, all the switch does is signal the BCM, and then the BCM decides when it's OK (if ignition is on) to power up the trunk release motor.

But I was thinking the same thing as you...........maybe you could just power up the car's ignition (I think you're going to want ignition, not accessory) circuit.

Maybe if you just applied power to one of the fuses in the fuse box that's on an ignition-controlled circuit, it'll power up enough other stuff to let the trunk release work. Kind of an at-your-own-risk thing, of course.

If you're able to get to the wires for the ignition switch, you could power up the ignition circuit right there, and that should do it.

On American and Asian cars, you should be able to get away with powering up just the ignition wire like that.

On European cars, it's riskier. I did a remote start on a Volvo, connected just one accessory wire incorrectly, and that triggered an airbag light that could only be reset by the dealer. So I'm thinking that if, for example, you powered up the ignition without powering up ALL the accessory wires, you could get the same thing.

There's no hard and fast answer is there? Chris L's advice is pretty good but then I looked at a new Volvo recently, lighting switch and trunk and fuel filler,  2 x CAN wires! Ditto UK Vauxhall  (Saturn)  Astra , ignition, wipers, washers, indicators and headlight flash, 4 wires! Only do it if you know, please use the audiovox sight.

Thanks for all the info guys. I will take your advice and try and jump the ignition wire at the fuse panel.