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2003 Chevy Trailblazer LT Repair work done now new problems HELP

I just had the alternator replaced on my Trailblazer. At the same time I figured I would save some labor cost and replace the serpentine belt. Got it back from the shop and it ran great for about a week. Now it when it is idling or at low rpms it dies or almost dies. After some looking around on the internet I decided to check the transmission fluid. I followed all the steps in the manual on how to check the fluid and it was very low. I put in some transmission fluid and it seemed to help a little. It isn’t dying anymore while idling but still running really hard at low rpms and after a bottle of transmission fluid it still says its low. The Check Engine light has come on and blinks when accelerating and to top things off the cruise control stopped working. The vehicle has about 160000 miles on it. Bought it used so I don’t know some of the prior maintenance details. Any helpful suggestions on what might be wrong?

Get the code read at AutoZone or Advance and report back. We can be much more help if we know that info.

Not much of a relationship between rough running and low transmission fluid. If the trans is low you need to add fluid. Some need to be checked hot though in park while running so follow the owners manual instructions. Its possible that they disconnected the battery when replacing the alternator and the engine needs to relearn the fuel settings and so on which can take a few miles. As said, the engine light means that a trouble code has been set so that needs to be read first. They might have failed to reconnect something in the process.

Why did the alt fail? Did u have a no start issue? Dead battery? Yes, sometimes the alt fails slowly. It works/does not work. Owner may nurse it along for awhile. Sometimes it dies. Bang. U are forced to take it to shop right away. Was truck running fine even with bad alt?

If the Check Engine light starts blinking it indicates a major engine misfire. Continuing to drive the vehicle with a blinking Check Engine light can result in damage to the catalytic converter.

You need to determine why the Check Engine is coming on and is blinking. Otherwise you’ll be replacing the cataytic converter also.


The code reads as cylinder 6 misfire. The guy said it might be the spark plug. Is that something I can do on my own? I have a small small amount of knowledge about cars. To answer earlier question the alternator failed slowly.

If it is the 4.2 Plugs were due for a change at 100 k. They are coil over plugs, that from what I understand can be delicate to work with. I had mine done,and it was not cheap, so it must be a little difficult.Gas filter should be every 30k, and air filter as needed.


You might also have dirty injectors

As for the transmission fluid, if it is very near the cross hatch marks don’t add until you check the level after half and hour of driving. When fully warmed, if the fluid is in the cross hatch marks, even near the bottom, it is OK.

And if you are hesitant about pulling plugs don’t pull them unless you have backup transportation and a comfortable place to work and a basic tool set.

I replaced the plugs…Not too hard only cut up one knuckle. BUT Check Engine Light is still coming on and blinks when accelerating. So far It no longer dies when low idling. It still seems to be running a little hard. A friend suggested dumping a bottle of fuel injector cleaner in the gas tank. I have heard they don’t really do much…thoughts?


If you want to clean your injectors, you need to hook up a canister type fuel injector cleaner directly to the rail

That junk you dump in the tank isn’t very potent

I was working on my Corolla last month on a throttle body problem, had a bunch of stuff removed and temporarily disconnected for clearance purposes, and when done and put back together for a test, the car would barely idle, a lot of coughing and weird noises, and the CEL came on immediately. Which it had never done before, except during diagnostic testing. Turned out I had accidentally forgotten to plug in the coolant temperature sensor connector. The ECM apparently doesn’t like this. Not at all. Anyway, once I plugged that back in, the idle returned to normal and the engine ran fine. It’s probably something like that.