CarTalk.com Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

2002 chevy trailblazer LTZ

hello folks, im new to this forum, so be gentle please, i was just wondering if anyone else was having a problem with there lights flickering when they take there foot off the gas and/or apply the brakes? thanks

Inspect the battery cables, clean and tight,no corrosion, check the large cable that goes down to the starter (the retaining nut could be loose, I have seen this)

Also check the large wire at the alternator,and of course all grounds.

You could get (I would) a charging system check out.

Ant chance trailer wiring intermittently shorting out?

i appreciate the advice and ill get on that first thing in the morning.

what is a charging system check out and how much is it?

ive only towed once to go floating. we all piled in so nobody was following to let me know, however when we got back to the truck 5 days later it was dead. i had to get a jump.

This is a common issue known to the Trailblazer/Envoy platform if you have the Atlas I6 engine. The reason it happens when you lift off the gas after cruising is that A.I.R. system kicks in then and draws a lot of power. It occurs most as the outside temps drop and the system is called upon to operate more often then. If it has gotten progressively worse, it might be that your AIR valve is going south. If you notice, an air pump runs when you first start the engine. It sounds like a small leaf blower under the driver’s seat. When the valve begins to stick, the pump is commanded to run harder and longer to accomplish the same task. This draws more power and the lights dim. Due to the power distribution and alternator scheme on this truck, the bus voltage tends to dip momentarily.

Edit- I should have added that the problem can be made worse if you drive off immediately after starting. The AIR system goes through its intialization and calibration phase immediately after each engine start. If you wait 20 seconds, it might help if everything else is normal.

thanks for the advice, i still havent been able to get to the first advice yet. i know pretty lousy on my part. the A.I.R system your talking about is what allows the windows to roll up/down after the key has been taken out correct? i have certainly noticed what you described as a leaf blower i call a big rig. could this be the same fan you refer to? also is it easy to fix, or would i need to take it in? i was also told maybe to get a bigger battery. would that be part of the charging system test that “oldschool” was refering to?

A.I.R. = Air Injection Reaction, part of the vehicles emissions control system, now the system that allows you to operate the windows after the key has been removed is called R.A.P. = Retained Accessory Power, the two are not reated, and not part of the charging system. At least that is how I understand AIR, is there some kind of pump inside the car? and what is it’s purpose?