Tach problem

[LeSabreUltra]

A while back, I posted a thread about a problem my S10 was having stalling out, etc. After months of trying different things, I finally gave up on it and took it to the Chevy stealership. $1k later, and it's good as new, with a new wiring harness and a belt tensioner in an unrelated incident. Some other maintenance stuff done too.

Turns out my tach was spliced into the wrong wire and fried the harness. I spliced it into the white wire with a black stripe coming off the coil when I was supposed to just hook it up to the plain white one. I didn't see the black stripe at the time. It worked fine so I didn't know the difference until a few months later when, yes.

So they told me all this and pointed me in the direction of the right wire, but suggested against doing it for the possibility of having to go through all this mess again. So I figured ok, fair enough and let it go. But having stared at my tach sitting there dead and useless bolted onto the A-pillar I've begun to miss having the damn thing.

Let me start off by saying that while I'm pretty good at a fair amount of engine work, I suck and don't trust myself at all when it comes to taking the dash apart. I wouldn't know where to begin, so swapping a different gauge cluster or trying to find the mystery white wire behind the dash is sort of out of the question, for now.

But like I said, I would really like to know what the engine is doing. I have a 96 S10 4.3 2wd automatic, and the tach is a Sunpro SuperTach II. I had the wiring all set and everything seemed to be working nearly perfectly, it idled at 500 rpm (which I know is off) and shifted at 5000 if floored. I don't see how it could have worked if it was the wrong wire, but then I don't really understand all the electronics of the engine.

Now I did find the right wire by the coil, but the problem still remains with the stealership's recommendation. I really don't want to fry my truck again. Is that a possibility?

Anyway, any comments or suggestions are welcome.
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[laydout97]

You can go off the wire from the computer on the passenger fenderwell. There are 2 harnesses connected to the computer. Its the bottom harness. 10th pin should be white wire. There is a place on the passenger side of the firewall to run the wire through. its the same place the antenna runs though. hope this helps. oh and the dealership thing... i have had my tach ran the same way as described for 3 years and havent had the first problem.

[LeSabreUltra]

Quote: Originally Posted by laydout97

You can go off the wire from the computer on the passenger fenderwell. There are 2 harnesses connected to the computer. Its the bottom harness. 10th pin should be white wire. There is a place on the passenger side of the firewall to run the wire through. its the same place the antenna runs though. hope this helps. oh and the dealership thing... i have had my tach ran the same way as described for 3 years and havent had the first problem.

Thanks, I'm going to try that tomorrow during daylight. I think I remember the hole in the firewall you are talking about too, I came across it while I was digging around over there looking for wires.
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[laydout97]

Quote: Originally Posted by LeSabreUltra

Thanks, I'm going to try that tomorrow during daylight. I think I remember the hole in the firewall you are talking about too, I came across it while I was digging around over there looking for wires.
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I would take a pic for you to show you where that wire is exactly but my truck is in a million + 1 pieces....

[LeSabreUltra]

My ECM might be a little different, I seem to have five connections.



Two stacked on the right and left, and that little one in the middle.

Any idea which one of these it is? I'm half tempted to just connect it at the coil, only problem is I'm worried about the possibility of shorting it out again. If only I knew why it shorted out to begin with...

What exactly is that white wire with the black stripe coming off the coil? Why would it have shorted out over a period of a few months after I connected it?
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[LeSabreUltra]

Nevermind, I got all pissed off at it and took apart the bezel surrounding the gauges, radio and a/c controls etc. Found the harness going to the gauges, which had three white wires. Of course, the first two I tried weren't the ones I wanted but the third one was. All is great!
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[madscientist101]

DOnt Use SUNPRO! I used the super tach 2 and it worked fine for two days, then the readings were wrong just like what you are expirencing, then a week later it stopped. I learned the hard way and bough a simple autometer Tach that gets connected the same way. Sunpro may have been the greatest thing back in the good old days but now its paper weight not worthy for putting on a go-cart in Ocean city NJ. I repeat dont use sunpro they suck, only there mechanical vacuum gauge was the only thing worthy of getting