For what ever reason in 2nd gen blazer's there is a common problem with the second air injection or smog pump, causing the check engine light to come on, and cause the vehicle to fail inspection.
The smog pump or second air injector pumps air into the catalytic converter to more efficiently clean the emissions. This is only mandatory by California law, but manufacturers put them on all cars now. Since the unit is there, weather it is needed or not, the computer communicates with it, and if it is not working then you will get a check engine light and fail inspection.
The cause for this is usually due to water getting into the pump and causing it to fail. A replacement for this unit is starting at $100. Most of the time it is a very simple fix.
When water gets in the pump or line, it causes the pump to have greater load, and blows the fuse.
The fuse is located next to the battery in the passenger side fender. It is a 30 amp MAXI fuse available at any auto parts store, and other stores like Walmart.
How to check and replace the fuse.
- Remove battery terminals. Positive first, followed by negative. Be careful not to hit any metal on the car with the wrench while taking off the positive terminal. It will make a big spark and possibly damage the battery.
- Loosen the battery clamp located on the side of the battery towards the fire wall.
- Carefully remove battery and place on anything other then a cement floor. Putting a battery on a cement floor is bad for the battery, although this short period of time most likely will not hurt it, it is a best practice not to put it on cement.
- Left of where the battery was in the fender you will see, one of the horns, and a unit which has covers over the fuse, and a relay. Remove the cover on the fuse by pressing the release tab and pulling. It should come off very easily. You will see a big green MAXI 30 amp fuse, and a small 10 amp fuse.
- Pull out the big green fuse and inspect it. If it is burnt, or the element inside is broke, then replace the fuse with the same. Check the 10 amp fuse, although usually this one does not blow.
- Replace cover, it will snap on.
- Put battery back in and tighten the battery clamp.
- reconnect the battery terminals starting with the negative.
You are going to want to test to see if the pump is working. Here is how to do this.
Under the front of the blazer there is a skid cover with a small door to access the oil filter.
- Use a flat head screwdriver to open this door with a half turn.
- Looking in the door, look up into the passenger side. You will see a black dome type thing. This is the pump.
- Start the blazer then go put your hand on the pump
You should feel it vibrating a little. Then you know its working. It does not run constantly so it may stop while checking it.
You will also know it is working when the check engine light no longer comes on.
If the fuse is not bad and the pump is still failing, the pump needs to be replaced. This part is big bucks from the dealer, so get it elsewhere. You can find it online for around $100. You can save your self some cash by doing it your self.
- Using a jack and jack stands, raise SUV a sufficient amount to access Skid plate and pump.
- Remove bolts that hold skid plate on.
- Remover torx bolts that hold pump on.
- Un plug all harnesses.
- Disconnect hoses.
- Install new pump
- connect to hoses.
- mount pump with torx screws.
- Connect all plugs from harness.
- Replace skid plate.
There is a service bulletin from GM concerning this problem. It has to do with rerouting some hoses to prevent water from getting into it. You can find info Online or at your dealer about this.