One problem related to service engine light on has been reported for the 2007 Chevrolet Trailblazer. The most recently reported issues are listed below.
The service engine light came on. As I was driving home from work at night, the external and internal lights would dim and then return to normal. I later found out that the front lights would completely go out for a brief second or two and then turn back on. When I got home, there was an odd fan/vacuum noise from my engine. The noise was coming from the air filter area. The noise would turn randomly start and stop and run for several minutes. I unhooked my battery, but my battery was completely drained in the morning and the car would not start. I replaced the battery but the check engine light was still on and the noise would randomly start and stop, most noticeably when the vehicle was turned off. I took it to an auto repair shop and was advised the issue is the a. I. R pump relay - in-line6 and the a. I. R system pump - in-line 6. The labor description from the auto service states "check service engine soon light and abnormal noise from engine area. Perform diagnosis fault code p2431 for air injection system. Further testing found system not working at this time. Further testing found air pump relay connector melted shorted. Problem due to internal failure to secondary air injection pump worn needs replaced. I have my vehicle scheduled to fix this issue tomorrow when the repair facility can get the parts in. I was told this was a very common issue with the Trailblazer. The auto repair man also told me that this puts a huge drain on the amperage, thus causing safety issues of the battery draining and the vehicle not starting in potentially dangerous situations. Additionally, with the air pump relay connector melted and shorted out - this is a potential fire hazard. I believe this issue should be covered under recall or warrantee due to the frequency, known issue, and potential hazardous conditions.