My Service Engine Soon came on in sub-zero Temps. Don't know what code it threw yet. Decided to investigate on-line and began learning about the Secondary Air Injection System and the pump. YouTube videos and info elsewhere say there is a fuse in the passenger side fender well behind the battery, where the horn is. Well, I disassembled things and found the horn, but no fuse relay, or anything like it, in the access area. This is a 1999 Blazer LS. Was there a change in the location for the pump fuse at some point? Any ideas where I should look for this fuse?
Thanks for the help, guys.

 

here they are on my 2001

https://blazerforum.com/forum/genera...-fender-82985/

 

Thanks for the reply. That is exactly where I expected to find them, and what I expected them to look like. But, there is nothing in there with the horn on my 99' LS. Also, I removed the plastic cowling with the oil filter access door, expecting to see something like a pump to the right of the filter and on the frame. There is nothing like that there, and looks like nothing ever was, and no sign of something removed. The catalytic converter is relatively new and my "Service Engine Soon" light only came on in extremely sub-zero weather about 2 weeks after I bought the vehicle, which otherwise is in extremely good shape. REALLY WEIRD, huh? OR am I just really missing something on this vehicle? Any more ideas???

 

Take a look at your exhaust manifolds. See if they have the provision for the air injection lines. I understand that some of these truck were not equipped with an AIR pump. I do not understand what years/ models did or did not.

 

With some further research I think I have determined that my 99' Blazer was not manufactured with a air/smog pump. Two questions then:

1. What else would the "Service Engine soon Mean", as there is less stuff to go bad? I have been assuming it probably threw a P0410, but need to test for codes yet.

2.I think there is a descriptor in the VIN # that may indicate if the Blazer was actually made with or without the air pump. Does anyone how to determine this? I think it may be the sixth # in.

 

I don't know if its the same for other model years, but on '98: Overall, VIN "W" RPO "L35" does not have it. However VIN "Z" RPO code "K18" does have the A.I.R. setup.

 

I know if I start my 97 (vin w ) and let it warm up in the driveway it throws a o2 heater circuit code. But if I just start it and drive away it doesn't. And its been pretty cold here in south east PA. Like 15°f overnight

 

There are a multitude of things that could set the light off. You need to know the code to start tracking down the problem.

 

rockp2:
Mine has a "W". Is "RPO" part of the VIN#? OR is RPO something different?

toyhauler1283:
Your observation makes some sense cuz here in Minnesota with minus 20 below zero temps, I've had to let the Blazer idle quite some time to warm up. I just had a new O2 sensor or something like it replaced. What DTC did yours throw? Do I just have to reset the code? I am going to have a fuel pressure test next week. Maybe they can reset to code then for me?

 

"RPO" stands for "Regular Production Option" . Is is located either on the sticker in your glovebox or the sticker on the firewall along with many other codes. I came to learn this about my '98 ZR2 Blazer because the manifolds on my engine looked like the pic attached. However, I didn't have any other parts for the A.I.R. pump. The PO had replaced the engine with a pieced together S10 engine (probably from a junkyard based off the markings on many pieces). I went to the dealership and the parts guy thought I should have the pump, but then he took the time and went through the computer with my VIN and was surprised to see that my VIN and RPO does not have the pump. He learned something that day also. He also told me what I posted about the "Z" VIN, RPO K18 having the A.I.R. system. Suffice it to say, I put on a set of manifolds that were original to the truck.

If your engine is original to your truck, and your passenger side manifold doesn't have either the metal line in the pic or the port to screw the line into, I would say you definitely don't have the A.I.R system on your engine.