Results 1 to 13 of 13

Thread: check engine light

  1. #1
    Tuner in Training
    Join Date
    Jan 2020
    Location
    oklahoma
    Posts
    15

    check engine light

    i am having an issue with my check engine light
    when started it blinks really fast has anyone
    else had this problem its on my ls swaped
    04 blazer

  2. #2
    Senior Tuner mbray01's Avatar
    Join Date
    Dec 2013
    Location
    Slidell, La.
    Posts
    1,015
    Its either an electrical gremlin, short, or bad connection.

    Misfires will cause the light to blink, but not really fast. Likely an electrical issue
    Michael Bray
    Rusty Knuckle Garage
    Slidell, Louisiana
    20yr Master Tech.
    Advanced Level Specialist
    Custom Car Fabrication, Customization, High Performance.
    GM World Class Technician
    Shop Owner

  3. #3
    Senior Tuner cobaltssoverbooster's Avatar
    Join Date
    Dec 2008
    Location
    Nevada
    Posts
    4,452
    the light is typically tied to the alternator. might be a good time to give that voltage regulator a test.
    2000 Ford Mustang - Top Sportsman

  4. #4
    Quote Originally Posted by mbray01 View Post
    Its either an electrical gremlin, short, or bad connection.

    Misfires will cause the light to blink, but not really fast. Likely an electrical issue
    Concur. The MIL is signaled on directly from the PCM on the 04 blazer. What PCM are you running, and is it the stock cluster? . Cluster "bird brain" logic box on the 04 blazer illuminates the light when signal is given from PCM. Don't remember if this is a + voltage or a ground signal. Haven't seen anything in HP tuners as of yet that controls or blinks the MIL. Does anything else on the cluster freak out when you go key on or start it?
    Last edited by vettemakesemwet; 02-03-2020 at 11:04 PM.
    03 Z06 stock.......for now
    05 Siearra 5.3 daily
    I have realized that tuning is a rabbit hole. No problem diving down this hole, in fact I jumped willingly. Just want to avoid hitting every ugly rock or root on the way down it.

  5. #5
    Senior Tuner mbray01's Avatar
    Join Date
    Dec 2013
    Location
    Slidell, La.
    Posts
    1,015
    The ecm grounds the circuit, which is provided voltage through the cluster, which illuminates the bulb(led). On this vehicle there is not cluster logic involved, its a simple on/off circuit
    Michael Bray
    Rusty Knuckle Garage
    Slidell, Louisiana
    20yr Master Tech.
    Advanced Level Specialist
    Custom Car Fabrication, Customization, High Performance.
    GM World Class Technician
    Shop Owner

  6. #6
    I was looking at the diagram last night and it showed the engine control MIL wiring going into the "logic box" of the cluster. This may just be a pass through directly to the light as closer inspection of the diagram shows the pin for the MIL to be IGN, and it is inside the drawing of the logic box. Could be the 12V/B+ supply in the cluster is flaking, or still a problem external to it. I remember the ford hybrid mechanical/electric clusters used to have a problem where there was a transformer or something that put out the 12v for some gauges would crap out. We have a local guy that repairs clusters and radios we sublet that stuff to so I never really dug into one. I miss the days of fixing instead of just replacing stuff. Learned so much more on the job that way.
    03 Z06 stock.......for now
    05 Siearra 5.3 daily
    I have realized that tuning is a rabbit hole. No problem diving down this hole, in fact I jumped willingly. Just want to avoid hitting every ugly rock or root on the way down it.

  7. #7
    Tuner in Training
    Join Date
    Jan 2020
    Location
    oklahoma
    Posts
    15
    pcm is a 12576106 o/s is 12593058

  8. #8
    Tuner in Training
    Join Date
    Jan 2020
    Location
    oklahoma
    Posts
    15
    also having trouble getting dbc to work what do i need a different pcm or a setting on this one

  9. #9
    I am new to tuning. First things that come to mind here is I have a major shortage on info. Help me fill in the blanks, and I will try my best to help you.

    Vehicle: 2004 Blazer, 2wd or 4wd? This will be a 4.3lv6 DBC
    What did LS/Vortec engine come out of? year make model
    Did it come with this PCM: pcm is a 12576106 o/s is 12593058
    Did it come with a harness?
    Was the engine complete(intake, throttle body, was it already a DBC setup)
    Did the transmission come with the engine? was original 04 blazer transmission used?

    Posting your tune will be a big help as well.
    03 Z06 stock.......for now
    05 Siearra 5.3 daily
    I have realized that tuning is a rabbit hole. No problem diving down this hole, in fact I jumped willingly. Just want to avoid hitting every ugly rock or root on the way down it.

  10. #10
    Tuner in Training
    Join Date
    Jan 2020
    Location
    oklahoma
    Posts
    15
    Quote Originally Posted by vettemakesemwet View Post
    I am new to tuning. First things that come to mind here is I have a major shortage on info. Help me fill in the blanks, and I will try my best to help you.

    Vehicle: 2004 Blazer, 2wd or 4wd? This will be a 4.3lv6 DBC
    What did LS/Vortec engine come out of? year make model
    Did it come with this PCM: pcm is a 12576106 o/s is 12593058
    Did it come with a harness?
    Was the engine complete(intake, throttle body, was it already a DBC setup)
    Did the transmission come with the engine? was original 04 blazer transmission used?

    Posting your tune will be a big help as well.
    i think i got it figuied out it was just a setting on the etc turned it from one to 0 the harness i built myself by instruction from lt1swap
    got that next thing is to get the exhaust done

  11. #11
    Cool, glad you got it sorted. As for exhaust, just put turn downs on the headers/manifolds. Let em know you're coming from a mile away.
    03 Z06 stock.......for now
    05 Siearra 5.3 daily
    I have realized that tuning is a rabbit hole. No problem diving down this hole, in fact I jumped willingly. Just want to avoid hitting every ugly rock or root on the way down it.

  12. #12
    Tuner in Training
    Join Date
    Jan 2020
    Location
    oklahoma
    Posts
    15
    Quote Originally Posted by vettemakesemwet View Post
    Cool, glad you got it sorted. As for exhaust, just put turn downs on the headers/manifolds. Let em know you're coming from a mile away.
    it turns out that the pcm was bad cause i was having an issue with th trans not going into first run the test and everthing pointed to a bad vavle body that was not it so onward with more test and it turned out to be a bad pcm replaced it with one of same o/s and now everything works

  13. #13
    CEL and everything works?
    03 Z06 stock.......for now
    05 Siearra 5.3 daily
    I have realized that tuning is a rabbit hole. No problem diving down this hole, in fact I jumped willingly. Just want to avoid hitting every ugly rock or root on the way down it.