All 1997-2004 Corvettes are VERY sensitive to a low battery. So, if your battery is nearing the end of its life, or is low due to infrequent vehicle use, always-on accessories, etc., you may experience a variety of problems, including column lock and/or fuel shut-off problems. The typical quick fix is to fully charge the battery and, if necessary, briefly disconnect the negative battery cable, which will reset the vehicle computers. Obviously, you may also need to install a new battery, make sure add-on accessories such as cell phone chargers, radar detectors, etc., are disconnected. Note: The LMC5 does not use ANY power while the vehicle is off, so it can't in any way discharge the battery.


Q. What is included in the LMC5 kit?

A. The LMC5 module, a screw, lock washer, lock nut, a terminal removal tool, plastic caps, and plastic cable ties.

Q. If I lose the screw, nut, etc., what can I replace it with?

A. Here are the specs for the 4 items included with the LMC5 module, all of which are available at your typical larger hardware store:

  • A 1.5mm hex key. A 1/16 hex key may also work, but be careful of inserting larger tools that can damage the connector or terminal!
  • A #6/32 x 1/2" hex machine screw (zinc plated). You can use pretty much any machine screw that's 3/8" - 1".
  • A #6/32 internal tooth lock washer (zinc plated). You can use any toothed lock washer. The teeth ensure a good electrical connection to the BCM.
  • A #6-32 nylon insert lock nut (zinc plated). It's important to use a lock nut to ensure a long term connection. But, any #6-32 nut will work temporarily.

Q. While installing the LMC5, I dropped the screw down a street drain, or the store is out of the correct part, what will work temporarily?

A. The zinc plated parts listed above are best for long term use. But, in an emergency, you can use nearly anything that will connect the LMC5 black wire terminal to the BCM, or to a vehicle ground. Brass, plastic, stainless steel screws and nuts. In the part specs listed above, the #6 refers to the size (width of the screw), so you can try a #4 or #2, but a #8, 1/4", 5/16", etc., will all be too big. Make sure that the screw, washer and nut sizes match, and tighten them as much as possible. The lock washer can be omitted temporarily, if you can't find one. In the part specs above, the 1/2" refers to the length of the screw. A screw shorter than 3/8" will be harder to work with and may not give the lock nut enough threads to grip, and a screw longer than 1" may protrude beyond the BCM. An easy, tool-less, temporary option would be to use a 1/2"or longer #6/32 screw and a wing nut that you can tighten by hand. You could even use a C clamp or a couple of alligator clips temporarily! Of course, don't count on any temporary fixes to last a long time, especially considering the amount of vibration in a car, the possibility of a passenger kicking lose a clamp, etc. Please replace whatever you may have used with the correct screw, lock washer and lock nut, as soon as possible.

Q. What other tools are necessary to install the LMC5?

A. Only two tools are necessary, a 1/4" wrench for the hex screw, and a 5/16" wrench for the battery cable and lock nut. It's easier to use a 5/16" nutdriver for the lock nut, but you can use a wrench, nut driver, socket and ratchet or whatever tools you have and are comfortable with using. The hex screw has a screwdriver slot, so you could use a screwdriver to tighten it (but a wrench is usually better). A small screwdriver can be useful to pry the plastic clips off of the connector locking tabs. You also may want to have reading glasses handy, if your eyesight isn't what it used to be.

Q. Do I really need to use the cable ties?

A. No. They are provided to help keep the new LMC5 wires in place next to the main harness wires, so that the new wires can't get wedged out of place, and possibly damaged when reinstalling the BCM, kick up panel, etc. As long as you're reasonably careful, you don't need to use them.

Q. Why the negative battery cable?

A. You can actually remove the negative OR positive cable (or both). But, in a negative ground car, the negative battery terminal is connected to the chassis. If you remove the positive cable, you run the risk of your wrench accidentally touching a piece of metal that is connected to the battery negative terminal. This can result in a short circuit, with the very real possibility of sparks and potential damage to the battery, your car and/or you! Sparks are NEVER a good idea around car batteries. So, please always disconnect the cable from the negative battery terminal. The negative terminal is indicated by a minus sign on the battery, and the cable should be black, but sometimes cables are replaced incorrectly, so don't rely only on the cable color.

Q. Do I really need to disconnect the battery?

Yes... usually. If your Vette is running fine (with no column lock or pull key messages and no fuel shut-off), AND you've done this installation before AND you have a lot of experience with vehicle electronics, AND you are willing to risk damaging your vehicle, AND you agree to hold us completely blameless for any problems that may occur, then it may be possible to install the LMC5 without disconnecting the battery. We will NOT be responsible in any way, for anything, if you do this installation with the battery connected! You do this at your own risk. Keep in mind that you may destroy your very expensive BCM, cause shorts, blow fuses, etc., if you make an installation mistake with the battery connected. We very, very, very STRONGLY recommend that you disconnect the battery! But, if you're an automotive or electronics professional, or you were born with a soldering iron in your hand (ouch!), or if you simply don't want to take that extra 30 seconds to disconnect the battery, and then yet another 30 seconds to reconnect it, email us. We'll give you more info along with more disclaimers.

Q. I'm not really up to installing this myself, can I have a mechanic install the LMC5?

A. Of course. Although we'd always recommend using professionals that are familiar with working on Corvettes, the instructions and techniques used in the installation are quite simple and should be easy for any competent mechanic to complete. The installation requires no specialized knowledge about Corvettes, and also requires no major disassembly or removal of any body parts or systems. So you really don't have to worry about someone not fitting your dashboard panels back in properly, etc. Of course, any potential installer should be familiar with vehicle electrical systems and connections.

Q. My car isn't running right now, can I still install the LMC5?

A. Absolutely. Whether your Vette just has a dead battery, you're waiting on a couple of new parts to arrive, or you're one month into a six month rebuild, you can always install an LMC5. Of course, you won't be able to check the installation until it's running. We always recommend installing an LMC5 when the installation can be tested right away. That way you're more familiar with the process, so it's easier to check and debug (if necessary). You also won't have installed or modified twenty other things. And, it's just a good idea to test every significant installation as soon as possible. If your steering wheel locks, you can also unlock it with the LMC5 Unlocker, even if your car isn't running.


Q. I still get the service column lock or pull key messages, and/or the fuel shuts off at 2 MPH.

A. The most common reason for these is a low or failing battery. If you experience these problems, charge, test and/or replace the battery as necessary. In rare cases, you may have to briefly remove the battery negative cable to reset the vehicle computers. If these problems still occur or are intermittent, you may need to have the vehicle's electrical system and/or BCM checked.

Q. I connected the LMC5 orange and purple wires backwards, and I now get the service column lock message. Am I screwed?

A. No. As soon as you realize your mistake, remove the key and disconnect the battery. As long as you only switched the LMC5 orange and purple wires in the connector, you'll be okay. The design of the LMC5 will ensure there is no permanent damage to the LMC5 or the BCM. You'll need to disconnect the battery and repeat the installation procedures related to those wires and the connector. On the other hand, if you connected the LMC5 to the wrong orange wire in the connector, or switched the green and purple wires, etc., then, yes, you may be out of luck. Since we can't plan for and prevent every installation mistake, the burden of being accurate is on you. Always double, or even triple, check your work!

Q. I forgot to connect the black (green, orange, purple) wire, and I now get the service column lock message. Am I screwed?

A. Probably not. As soon as you realize your mistake, remove the key and disconnect the battery. Repeat the appropriate installation steps. Since double checking your work didn't seem to help last time, maybe you should check it 4 or 5 times now.

Q. After reconnecting the battery, the interior lights (or DIC, gauges, etc.) don't work. What's wrong?

A. With the vehicle off, check that all three connectors (green and pink) are firmly attached to the BCM. Then, check the BCM fuses in the fuse panel. If you find a blown fuse, check that you've connected the LMC5 wires to the correct connector terminals and replace the fuse. Try it again. If it still doesn't work, or no fuses were blown, check that each LMC5 wire goes to the correct terminal, that each is fully seated, and that the LMC5 black ground wire is attached to the BCM.

Q. I did everything right and my car was working fine before the install. Now, I get the column lock message. Could the LMC5 be bad?

A. It's possible. Please go through every part of the installation and make sure everything is properly connected and reconnected. If it still doesn't work, we'll thoroughly test your LMC5 for free, as long as you pay for shipping both ways. If the LMC5 is good, we'll send it back to you. If the LMC5 is bad, and it's still under warranty, we'll send you a new one free. And we'll pay for shipping it back to you. Although we test each LMC5 multiple times throughout the manufacturing process and again prior to shipping, unexpected failures can still occur. Fortunately, they are quite rare.

Q. I've had all the recalls done and my Vette is running great, should I still install an LMC5 right away? or

I've never had any recalls done and my Vette is running great, should I still install an LMC5 right away? or

I've had another relay based replacement device installed and my Vette is running great, should I still install an LMC5 right away? or

What if I don't want to install an LMC5 right away, should I get one to keep in the glove box as a backup for emergencies?

A. Yes, yes, yes and yes. Of course we think so! Since the manufacturer recalls have not eliminated the column lock problems, you could still be stranded at any time. And, just like the hard drive in your PC, every relay will eventually fail. That includes the column lock relay, the relay in the manufacturer-added k harness, and any other column lock replacement device that uses a mechanical relay! Due to the superior reliability of the LMC5, combined with its ease of installation, there's no reason to take a chance and not install one right away. But, if you're not sure, just don't want to install an LMC5 now, or simply want to be fully prepared for a worst case column lock system breakdown, then at least keep an LMC5 in your glove box as a backup along with the installation tools and instructions. Maybe even take a few minutes some night and read through those instructions. That way, if your column lock system fails, you'll be minutes away from being back up and running, whether in your driveway, or 2,000 miles from home in the middle of nowhere. Remember, if you're not comfortable with doing the installation yourself, virtually any mechanic, anywhere, can easily do it in minutes - as long as you have an LMC5! But, hey if you get stuck 200 miles south of Coeur d'Alene at one am without an LMC5, don't say we didn't warn you. It's your car. And your time. And your money for a tow. By the time you get to a place with cell phone reception. At least Bigfoot's never been seen that far east. Or, has he?!?

Q. Is it always necessary to remove the lock relay connector in 6 speed C5s?

A. No. The LMC5 removes the switching portion (contacts) of this relay from the vehicle electrical system. All relays eventually fail, especially in high vibration environments like in a car. If you leave this relay connected, the only part still connected to the vehicle is the relay coil. When relays fail, it's usually the contacts that fail, resulting in an output short or open. Although a shorted coil is less likely, by disconnecting the relay connector, you avoid ANY type of relay failure.


Q. Who needs the LMC5 Unlocker?

A. If your steering columns locks, you'll need to use the simple LMC5 unlocker only during the LMC5 installation. If your steering wheel turns freely while the key is out of the ignition, you DO NOT need the LMC5 Unlocker.

Q. How do I use the LMC5 Unlocker?

A. The LMC5 Unlocker connects to the car battery with two battery clips, and stretches to the passenger floor, where you briefly connect the LMC Unlocker to the two steering column lock motor terminals.

Q. Is there a way to unlock the steering column in an emergency, or if I didn't get an Unlocker?

A Yes. There are a few ways. But, due to legal and safety concerns, we do not provide complete information on a procedure that may damage very expensive parts of your Corvette's electrical system. If you have an emergency, i.e., your Vette is stuck somewhere and the risk to life or property outweighs the relatively small risk of damage to the electrical components, please contact us and we'll try to help. Basically, the steering column lock motor wires are briefly connected to 12 volts and ground. The LMC5 Unlocker contains a fuse that protects you and your car in the event that you accidentally touch the wires together, to ground, etc. Also, by performing the unlock procedure as recommended during the LMC5 installation, the risk of incorrectly connecting the Unlocker is virtually nil.

Q. Do I need the LMC5 Unlocker if I have a k harness or another column lock bypass installed?

A. Almost certainly no. Every other column lock replacement device disconnects the lock motor under the steering column (the LMC5 disconnects it at the BCM). Your steering wheel would only lock if someone improperly installed that other device, or if the lock motor pin somehow engaged the lock plate.

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Who Needs An LMC5?
LMC5 At-A-Glance
LMC5 Description
C5 Column Lock System
LMC5 Installation
LMC5 Unlocker
LMC5 Tool Kit
LMC5 Troubleshooting

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