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ERIC KOHNKE, Auto Mechanic
Category: Car
Satisfied Customers: 58
Experience:  Have worked on this exact vehicle and similar issue before.
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97 Chevy Blazer Service Engine Soon Light On

Customer Question

1997 Chevy S10 Blazer, 140K Miles. Kept up on normal maint.
This weekend i just replaced the factory speakers in the front door panels, with Aftermarket MTX speakers rated at 130Watts each. No Problem, i have an aftermarket Stereo with 220Watts power. However after replacing the engine did not want to stay started unless i had the accelorator pounding at 2K+ RPM. After about 10Seconds of this the engine stayed started with no problems. Shut down, waited a few minutes and started up again. Today went out to start it with no problems, letting it warm in the 39 degree temp before going to work. However when i came out of my house after letting it warm up for about 10 minutes i noticed the Service Engine Soon Light was gleaming at me. It drove to work fine with no problems. In the past i have had this problem along with the Airbag light staying on as well. I remedied this by disconnecting the battery negative cable for about 10 minutes. This light usually comes on 1 or 2times per year. Seeing that i do all my own maint for easy stuff such as spark plugs, rotors, oilchanges, airfilter changes. I tapped the EGR Valve at the base where it mounts to the intake, and that did not turn the light off, and i suspect it is not an EGR problem, as the light would be coming on more if it were. I checked the electrical connections at the computer, as well as that little trouble spot on the drivers side fender wall as well. Checked the little black ignition switch under the dash, as far as i can tell that is good as well. I have only had to perform very minor maint on the blazer, and i am guessing i am one of the few (Knock on Wood) to not have major problems with my blazer
Submitted: 11 years ago.
Category: Car
Expert:  ERIC KOHNKE replied 11 years ago.
Well most likely if you try to reset that light it will not come back on, my guess from you sad is that either the battery or alt. is geting weak, and that the stereo is drawing enough power to make it have idle issues, which is why the light is on maybe a ruff idle code. That obviously is not a for sure, but if you wanted to see if there could have been a coinsidence between the two there is your posibility. THe other thing resulting in the ruff idle is that the radio could be drawinng power with the vehicle shut off, or a key off battery drain, which also could make to much work for the alt. after starting causing the vehicle to have a ruff idle, do to the fact that the alt. cannot keep up. Thanks for the question.
Customer: replied 11 years ago.
Reply to ERIC KOHNKE's Post: This is not an issue with the Radio, however it could be with the alternator/battery. However i am not sure how that would effect the SOS light.
Maybe it just tripped something in the system. However the battery was just replaced last year. It had some crappy battery in it that would no longer hold a charge, and i went to sears and had a die hard installed on it. Also i read out the readings with a mulitmeter on the alternator. It appears the alternator is doing its job as normal. It is not an issue with rough idle, as this only happened 1 time where i had to gas it to keep it running. Now it starts, but the SOS light comes on, unless of course i disconnect the negative battery cable for a few minutes to reset the computer.
Expert:  ERIC KOHNKE replied 11 years ago.
Ok well if you do not think it is a ruff idle, then I would suggest having the free scan done at autozone so we can try and get closer to the issue. Also you said the light comes on a few times a year, and I am guessing that nothing seems to be affected. Are you aware that a lose gas cap can set this code off, most people are not aware of this and I just htough I would bring it to your attention. Also you said above that the car did not want to stay started unless you held it at 2000rpms, the fact that it would not idle could set off the ruff idle code, also that is where I was getting with the voltage problem. Having to hold the rpms higher is normally consistant with a weak battery or alt. Thanks again.