03 Chevy Blazer at times won't start

I like a little help on this.  I have a 2003 Chevy Blazer with 46,250 miles on it.  At times, I will go start it and nothing will happen.  I try to put it in start mood and nothing will happen.  It will do the normal turn off the radio and other lights, but it appears something is blocking the starter from functioning.  If I wait a little bit, it will start.  This problem seems to be happening more.  And it seems I have to wait a couple of minutes before it will start.   This problem is tempormentallish and if i take it to a garage, the mechenic won't be able to dianostic because it will usually work for him.  HAve anybody had this problem.  Like to have some insight.  

Does the engine turn over and rev up, but then shuts off?  And does your security light flash when it does this?

And ya gotta love the good ol 'could not replicate'

No, pretty much the security system, I/we determined not to be the problem.  I took it for a dianostic at my garage.  It did show that there was a lost of communication with the transmission and the ABS.  He said that is something to go on.  Sometime he also said Chevy has can have a bad grounding.  It also showed a heater core of an O2 sensor is bad so that will be replaced and they will check more indepth on the starting problem.  Anybody that had a simalar problem I welcome some advice.

You can get a heater circuit malfunction code from a bad ground as well.  I would start by cleaning all of the grounding points. The most difficult one is on the back of the passenger head.  Just so happens to be the one that causes a lot of problems too.

Well, today, my Blazer came back from the garage.  They could not find anything.  Then when I left the garage, my check engine soon light came on again.  Not very happy.  However, I had no problem starting the vehicle since last Wednesday evening(3/13).  Does anybody know, do GM dealers have access to codes that Independent garages don't?  I think its dumb for these dianostics to tell you that there was a communication loss but not tell you what the problem was.  If anybody has insight on this, replies are welcome.

It all depends on how elaborate of a code reader the shop has.  Many cheap code readers cannot read anything but generic and some manufacturer specific powertrain codes (Pxxxx), but do not include the chassis (Cxxxx), body (Bxxxx), or other sub-system codes. 

Without the specific code you were getting, I cannot recommend a direction for proper diagnosis of your problem.

Ok, I talked to the garage mechanic today, and this is what I learned.  The check engine light dose not appear to be a new problem, as I learned that they didn't put a new O2 sensor in.  He showed me the Pxxxx code that are common.  That had to do with the O2 sensor.  Then there was too other codes.  (U1026 and U1041).  The U codes he mentioned is a body code.  Does that sound right?  But these 2 codes are whats they can't figure out.  The diagnosis code reader comes from Snap-on and I suppose thats not consider cheap.  But it doesn't tell the exact problem with the U codes.  So what do anyone believe should be my next step?

One last thing, I did go a whole week without the starting problem.  But that doesn't really tell me anything yet.  But better then having it happen to me twice last week.

Well, what was the Pxxxx code?

U1xxx (Loss of Communication) Explained
U1026 == Loss of communication with the TCCM (transfer case control module)
U1041 == Loss of communication with the EBCM (electronic brake control module)

Neither of these should cause a no start condition...

I got my code today.  It is P0155. 
What would cause a loss in communication?  Is that something that I should be concerned about?  Next month I have an emissions test due on the Blazer, and I can't pass it with the Check Engine soon light on.  So if the engine has no problem starting and we have nothing to go on, i will concentrate on passing the emission test.  

P0155 Explained

No, this would not cause the loss of communication.  I would take a look at the causes of the loss of communication as provided in the link I posted in my previous reply. 

Well, things are looking better.  Had not had a starting problem for 3 weeks.  Garageman told me an old battery does wired things to a vehicle.  He believes it was the battery.  The lost of communication codes are gone.  But the Oxygen sensor code he still has to work on yet.  

For the O2 sensor code, I would swap the sensors side to side B1S1 to B2S1 and vise versa.  If the sensor is bad, the code will follow the sensor.

Last Thursday, my garage detected that it was pretty much the sensor and elimiated all possibilities.  Replaced the sensor.  That evening, the all to familiar "Check Engine Soon" light came on and was not welcomed.  Told my garageman the next morning, hook up the machine and got code P0154 instead.  He said, same sensor would have done that.  Bad sensor out of the box?  He turned it off and light have not been on since.  Took a 250 mile round road trip this weekend with no problem,

P0154 Explained

It is in fact the same sensor.  It is possible that it was bad out of the box.  Depending on the brand of sensor, it could just be a crap brand.  Bosch sensors are junk IMO which is based on first hand experience with a side by side comparison against an AC Delco sensor.

Oooh, last night the starting problem reared its ugly head again after a couple of months.  Those Service Engine Soon lights that have been mentioned before been repaired by new O2 sensor.  The light has not been on since so that is not the problem.   But I have done that before already and it still didn''''t start.  Back in March when it was in the garage, the battery was replaced, and the mechanic dianostic it all afternoon and found nothing.  He replaced the battery because it was 5 years old and leaking but showed a good charge.  He recommend replacing it so I did.  Since  the problem hasn''t happened, he thought it was an old battery. Anybody have any ideas?

well my blazer had kind of the same problem, it would work fine, then the next day it would not start, so i took itand got the battery replaced, like you did, and the problem went away... for about a month, then i took it to a GM shop and they found the alternator was not properly charging the battery. i dont know if this is the same problem you are having, but take it to a certified GM garage. have them check the wires to the battery and anything that deals with the charging system... hope this helps

Did you have to jump start it?  I never had to jump start mine.  Is there certified GM garage that is not a dealer? 

As it turned out. it was the starter it self.