Recently a 2005 Chevrolet Avalanche came into one of our shops with the customer concern of the transmission sticking in one gear intermittently, and the Service Engine warning light illuminating. When I went to start our pre-diagnostic evaluation I grabbed the scan tool and went out to the vehicle, only to notice that it had a “Smart Start” ignition interlock device installed (Figure 1).
At this point I decided to hook up the scan tool and check for codes before driving the vehicle, and I pulled codes P0740, P0753, P0758, P0785 and P2761. On the basis of these codes, we advised the customer that he had an electrical issue and we would need some additional diagnostic time. The customer agreed and left the vehicle with us to diagnose.