As a young man, I was curious about how things worked. I took a lot of things apart around my house, much to the frustration of my parents. Many of the things I took apart never worked again. As I got older, the things I took apart got bigger. Eventually, I progressed to a lawn mower repair shop in the basement of my parents’ home. My story is common; I’ve talked to other auto technicians who also loved taking things apart.
Taking things apart to learn how they work was only part of my mechanical education. Once I had the mower shop, finding out what had failed became really important. After all, if I didn’t replace what failed, I wouldn’t get the mower running and couldn’t resell it to earn money.
This brings me to the subject of this month’s article. Last year, we worked on a 2002 Corvette that had developed a strange problem. After sitting for a while with the lock engaged, the alarm would suddenly activate when someone tried to use the passenger-side door handle.
Normally, when the doors are locked with the key fob, attempting to open a door doesn’t activate the alarm. But when you attempted to open the passenger door on this car, the alarm would activate because that door wasn’t locked. However, if it had been locked manually, the door stayed locked, and the alarm did not activate when attempting to open it.
This Corvette uses a lock motor built into the door latch. When using the key fob, the lock motor is supposed to rotate, mechanically locking the door. The driver’s door worked perfectly.
I started by taking the door interior trim panel off so I could determine why the passenger door lock motor was not working. After removing the door panel, I consulted the wiring diagram, which showed two wires — one tan, one gray — responsible for the door lock motor operation. These wires change polarity, which changes the direction of the motor’s rotation, causing it to mechanically lock or unlock the door latch. The wires come from the door lock module where the change in polarity occurs. After testing the wires, I found the lock motor was getting the command to unlock the latch but not to lock it. At that point, most technicians would repair the car by replacing the door module, but I wasn’t going to take the easy route. As I mentioned, I like taking things apart to see what has failed. The door module is several hundred dollars, so I wondered if it could be fixed. It was a slim chance, because most electronics can’t be fixed in the field.
After removing the module and disassembling it, I found that it used mechanical relays to change polarity. A quick internet search confirmed the availability of replacement relays. I carefully desoldered the relays from the circuit board and replaced them with new parts. Boy was I happy when, after reinstalling the module, everything worked normally!
This is a perfect example of how we like to do things here at SweetCars. It isn’t always as simple as taking the “easy” route to fixing a problem. We take the time to really learn what has gone wrong with your vehicle, identify how it happened, and complete the repair in a way to prevent it from happening again.
If you find yourself with a problem with your vehicle, stop by and let us take a look. We’ll make sure it’s done right!
