service engine soon light

I get this light on, first start up of the day. It seems the engine has to be cold to get it. I don't get any codes out of the computer though.
If I shut the engine off and restart, most of the time it does not
come back on, but if it does, it will shortly go out again.
I don't know if I am doing it right or not, but I got a key from Advance auto parts, and when I try to get a code, I turn the engine off, then key on so that service engine light is on, insert the key in the upper right two holes and all I get is code 12, which AAP tells me is "no codes stored."
Anyone have an idea about what could be going on here? I've checked all vacuum lines to make sure they are on. Truck is running good, "for a change." Just put new injectors in it. Until I adjusted the TPS voltage I was getting surging and cut outs after installing new injectors, and the light would come on and go off during this. 88 s-10 4wd.
Hatt
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Try putting the "key"(AKA "paperclip") in before you insert it.
My other question for you is how many 12's did you count? 1?2?3? There should be a total of 6 12's for no stored codes.
Sam

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sorry GaWd, I don't follow what you are saying. "key in before you insert it?"
and, 6 12's, I didn't know that, but I'll check how many times they blink. After 6 it should stop blinking?
Hatt

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K, DJ...
Insert your tool in the A and B slots before you turn the key.
I believe it will continue to flash, but 6 12's and it's officially done. 3 to open, 3 to close. Really, if you see more than 3 12s, you can turn the key to off and remove the paperclip because as I said, 3 12's will ALWAYS precede any stored codes if there are any.
Sam

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OK, got ya, I'll be right back

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Yep, that's a code 22. TPS circuit low voltage.
I'd check the connectors and associated wiring real good.
Sam

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I bought some connectors, butt connectors, and a digital voltmeter so I could set the voltage on this thing after replacing it and the injectors.
Following the instructions in my GM service manual, to the best of my understanding, [I've never used a voltmeter before], I cut some of the insulation on the black and and the blue wire, [as id'd by the manual], to the TPS, so I could get a reading.
The manual says it should read below 1.25 volts. It did, but it was .9 something and the manual ALSO says however, turn it until it reads 0.48v + or - 0.06 volts. I did so, ended up with 0.46 volts, called it good, and tightened it. Then I clipped the wires and used the butt connectors to hook them back up. I probably did something wrong.
Hatt

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Having never installed one, I'm at a loss here too.
Sam

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O2 open means the wire is disconnected or burnt...
You read the blinking lights by sitting through them all until the last set of code 12's appears. I'm assuming if this just showed back up that you've jostled the plug, burned the wire or something like that.
If you've bought replacement O2 sensors that needed a splicing(I.E.- needed a butt-connector to join the original wire), try re-doing the butt connector.
Sam

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