Technical Notes — September ‘10’ - Corvette THEFTLOCK...Flagler County Corvette Club —...

P a g e 4 Flagler County Corvette Club — Newsletter

Vic Natiello

Technical Committee —Chair

Technical Notes — September ‘10’ - Corvette THEFTLOCK

Continued on Page #5

THEFTLOCK is a security system for Corvette radios that was introduced

with the C5 generation. Now, this is not the vehicle theft-deterrent sys-

tem that was first introduced in the C3 generation. In the C5 and C6

Corvettes, the radio has this separate security system to deter thieves

from breaking into your vehicle and stealing the radio for use in another

car. As is often the case, however, thieves can be quite technically so-

phisticated and can defeat even nearly every security system if the item is

in high enough demand on the black market. Unfortunately, these sys-

tems can do more to frustrate the legitimate, but technically challenged,

car owner than the thief. So, let’s look at the procedures for setting and

disabling the security mode on the C5 and how to recover use of the radio should the security system ac-

tivate.

Since most late model Corvettes come with an owner’s manual that looks a lot like a college-level physics

book, I’ll try to keep this simple with plenty of pictures. Here is a page discussing radio security from a

typical C5 Owner’s Manual.


Please note the statement at the end of Step 9. Corvette engineers intentionally wanted to alert thieves

that the radio in your car had the security system activated. In my opinion, however, this feature could

be considered as an invitation rather than a warning. If the light is not flashing, you are basically telling

every thief you are an easy mark. Thus, you might not only return to a vehicle with a big hole in the front

console, but a lot of glass in one of the seats where the window was smashed by a crowbar.

Let me show some images of how the radio will look during these procedures. First, remember, the radio

must be off to set your personal security code. First, write down a code between “000” and “1999”. Let

chose “1234” for this example. At Step 4:




Now let’s suppose your radio is security enabled and your battery tender fails while your out West mak-

ing your fortune. When you return to Palm Coast, you find your C5 battery is dead as a doornail. Well,

first remember that the Corvette radio interprets the battery failure as radio theft. The radio will not op-

erate once you’ve fixed the electrical system, until you enter your security code. Thus, when you first

turn the ignition on, “LOC” (locked) will appear in the radio display. The following owner’s manual page

shows the procedures to get your radio functioning again. It actually tells you two procedures: (1) How

to unlock your radio after electrical interruption with “LOC” displayed and (2) How to disable the secu-

rity feature, if, let’s say, you were to sell your car in the future.




But, what if you lost or forgot your code after you got your new battery? In that case, you have two

choices. First, you could drive the car for the rest of your life singing to yourself, a cappella. However, if

have a spouse, that won’t work, so you’ll have to go back to the owner’s manual to figure out how to get

your radio back in operation. Look at the statement at the bottom of the left column on page 3-27. If

you enter the wrong code 8 times, you must wait an hour with the ignition on before you can try

again. Then, you only get 3 more chances before you see the dreaded word, “INOP”. Of course, male

owners will try all eleven times to guess at their code, and then take their car to the dealer. Women

owners are more likely admit to failure early and go to the dealer after a few failed attempts. In either

case, don’t forget to bring your wallet.




Your radio will now function, but is in the secure mode. The security code will be the four digits you ob-

tained via the phone. If you want to reinstall your own personal 4-digit code, follow the steps to clear

the security code and reinstall your own four numbers. Unfortunately, the special numbers “139010”

shown in the procedure above are no longer valid. GM changed that key a while ago. For security rea-

sons, the correct digits should not be divulged over the Internet. If you need the current numbers, you

need to find a mechanic who knows them or you could try to “pretty please” your local Chevy service

writer. If you really felt lucky, however, you could also ask around at Woody’s and someone there might

just know the key.

Now for this month’s bonus question: C5 radios, whether cassette or disc, have identical buttons and

the same display. On the other hand, C6 radios come with or without NAV, and as a result have dis-

tinctly different radio heads. How can you C6 owners enter your security code in those two distinctively

different systems to enable the C6 THEFTLOCK system?


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