I have a 2005 Trailblazer that has a few issues... My main concern right now is a wierd voltage drop. I can be driving along just fine, but if I let off the gas for a few seconds and "coast" the headlights dim and the volt meter on the dash drops from 15 to 13 momentarily then it returns to normal and the lights come back up. I can repeat this over and over again. The gauge always returns to normal after a split second even if I am still coasting.

 

*Moving to the GMT360/370 section* - The 2nd Gen Tech section is for 2nd gen s-series vehicles.

This is a known problem with the GMT360/370 vehicles with the 4.2L I6 motor. GM states that the problem is when the vehicle is not run sufficiently long enough when first started for the secondary air injection system to run its startup checks. When the AIR system cannot run its check, the pump will hard (full speed) start whenever the conditions are right for it to run which causes a huge draw on the electrical system. If the startup check is completed, the AIR pump can soft (ramp up speed) start with very little impact on the electrical system. The TSB that GM released on this issue states that the vehicle should be started and left to idle for 30-60 seconds prior to attempting to drive it.

I have not heard of anyone rewiring their alternator for battery reference control as opposed to the PCM control it has stock, but it may be worth a try. Another member just wrote up the details for the 2nd gen s-series trucks yesterday.

 

Thanks! Sorry for posting in the wrong area. It seems this issue IS related to my P0410 & P0455 codes then... Thanks again!