Hello, this is my first post on here. I had a 1989 Blazer years ago and loved it and now my husband and I just bought a 2005 Blazer.
We bought it from my boss knowing it has a problem but the price was right, so...
About half the time it doesn't want to start. It seems to be worse when it's cold but it'll do it warm, too. If you turn the key and the lights don't come on it's not going to start, if they come on, it will. When it doesn't want to start it just sits there turning over but won't catch. It's like it's out of gas.
It's also been stalling after being driven for a while and then doesn't want to restart. Just driving along, even on the highway, it'll just quit.
My husband thinks it's the ICM and/or something to do with the theft deterrent system- the truck is just not allowing itself to be started by cutting off the gas.
Any ideas? If it is the ICM we don't seem to be able to find any information on where it's located.
Thanks for any help you can give us. He loves the truck but we need it to be reliable. It has 170,000 kms on it.

Oops, I forgot, it's not throwing any codes.

 

Does the security light come on at all around the time that it stalls?

 

could be a bad fuel injector. i saw it on a grand prix where once he got it started it would run well for a while then it would stall out. not sure on the lights though. the fuel injectors would have nothing to do with losing electrical power. security? loose starter cable on the starter? battery terminal?

 

Thanks for fixing my post and for getting back to me so quickly.
Okay, the security light flashes.
To clarify the lighting part of it. If the key is turned to 'on' and the instrument cluster doesn't light up, the truck will not start if he tries it. If he turns the key to 'on' and the instrument cluster does light up, it will start.

 

sounds like a pass lock problem in the security or with the ignition switch, neither is my specialty. kyle knows his way around so he should have a hunch.

 

Classic signs of an ignition switch failure. Check out the link in my signature.

 

Thank you SO much! That sounds like it's exactly what it is. I'll pass this on to my husband. Would you have a link for how to install one by any chance? He's pretty handy and worked on our two Audis for years which is amazing if you've ever had that experience.
I'll be glad when he gets the Blazer back to being reliable as I still miss mine but driving my Mustang does make up for it.
Thanks again!

 

Tech Article (DIY) section to the rescue again:
Ignition Switch Replacement - Book Method... by swartlkk
98+ SIR Airbag Disabling & Enabling Procedures by swartlkk
PASSLOCK - Reprogramming Auto Learn by swartlkk
Ignition Switch Replacement by WolfPack

I don't think you'll need the airbag disabling procedure, but I included it just in case. For future reference, there is a nice index of tech articles --> Tech Article (DIY) Index

 

I just want to let everyone know that it was the ignition switch and the Blazer starts every time now and has a better start, too. It never did stall as the former owner mentioned so I don't know what was up with that.
Thank you so much Kyle! I downloaded the instructions and in a couple of hours we had a fixed truck, yay!

 

Glad you got it fixed up! Thanks for the followup!