U0168 Code for GMC

Two rather strange and sometimes creepy aspects of running an auto repair shop happen infrequently, but often enough, where I wonder about the cosmic balance. I call one of the occurrences the ‘Conjuring Factor’. If I really believed in it though, I’d be using it to drum up business whenever the shop gets slow. I keep a card file on customers and jobs. Yes, I also have a complete database with every customer and job on it, but the card file acts as my hard copy for quick access since I don’t keep anything of value in my front office, especially my notebook computers. Once in a while I’ll be flipping through the file at a customer’s request for info on a maintenance record when a name will jump out at me. Then, as happened today, I come in and find a message from that person about getting their vehicle in for service within a day of mentioning him to my wife. I hadn’t seen this particular customer since the beginning of last year. He’s a contractor and owns a relatively new 2007 GMC. The second creepy aspect is when what I call ‘Dumb Luck’ rears its head during a diagnostic check, which also involves my customer with the GMC I’ll refer to as Joe Acadia.

My wife asked about a certain type of electrical contracting because my son is searching the local real estate for a fixer upper home in his price range. I mentioned Joe to her and what do you know, his voice is on my answering machine. I call him up to schedule the repair he hints at in the message – his GMC won’t start occasionally.

“Sometimes my security light blinks on,” Joe explains after he drives in. “Then when I unlock it with the key, it won’t start.”

A number of possibilities float through my head: battery going out, body control computer losing the code it interprets when the key is turned to start or run, concerning security, or even a bad security component such as the mini-computer key goofing up because of a weak battery. People send those things through the wash by accident quite a bit too, and boy does that cause trouble.

“I’ll have to check it out, Joe. Hopefully, it’s just a loose connection. Anything that disrupts power to the body control computer can set a security code. Do you have an extended warranty on this?”

Joe’s silent for a moment, wondering if his answer will somehow affect the price. “It’s out of warranty. It already has more than a hundred thousand miles on it. I drive the crap out of it. I’ll leave it for you.”

He signs the estimate after I write up the sheet and I hook up the GMC to my software. It spits out a U0168 code for interruption of communication to the Instrument Cluster and Security Module. I do the usual quick checks for loose or corroded grounds and power leads – all good. Then it’s time to take a look inside on the column and see if everything jibes as I work the key. Suddenly, creepy aspect number 2 kicks in (Dumb Luck). I lower the telescoping wheel and the security light goes out. I work the wheel up and down, duplicating the problem with security light blinking on and no start. I sell the column harness and install it, thereby ending the no start and security light problem. Joe’s happy.

I, on the other hand, have now tempted the cosmic balance by having both conjured the customer out of thin air, and diagnosed his problem with dumb luck. Uh oh.  :)