The factory tach didn't work on the LS1/4L60E swap, which, from what I've read here, didn't surprise me too much. So, I decided to go aftermarket rather than try the pull-up resistor circuit. The first one I bought said "not recommended for use with distributorless ignition" (which wasn't on the packaging, only in the instructions), so I picked up another one. It had a list of tach signal wires which included the 2000 Camaro, so that was encouraging. But, it wouldn't work, either. Not even a wiggle out of either one. That made me suspicious of my wiring, so I attached them both directly to the signal out of the C105 connector (I got both the PCM and chassis side with the engine/trans) - still nothing.

So, I pulled the red PCM connector and C105 connectors, found pin 10, and ran a continuity check - nothing. Tried the white wire next to it, bingo, continuity.

Here's a pic:




Note the two white wires at the top (PCM side), and one coming out the bottom. The one coming out of the bottom was originally in the socket to the left - this is after I repinned it.

I would assume a 2000 Z28 would have a tach. Don't see how it could have worked with the connector pinned this way, though.

Anyway, the tach works now. Even the factory tach. Found out the spareecm reprogram didn't reset the tach output to 24/3 as I requested (his print-out didn't say he had; I traded messages with him asking about it and he said he had, but just forgot it on the print-out - it would appear his print-out is correct). I was just going to use the factory tach until I found out the output wasn't V8 style, so I'll be using the aftermarket tach (the 2nd one) in 4 cyl mode. I wired the internal tach light to switched 12v so it is lit whenever the ignition is on (nice when racing at night).

 

IMO I would have wired the tach light to any grey wire behind the cluster which would be the illumination circuit wires for the factory cluster, those little autometer bulbs burn out enough as it is.

 

I've had my Equus tach light wired to ignition in the '57 since the late 90's with no problems.

This is a Sunpro tach. Maybe they use better bulbs than Autometer.

 

Well, another reason i like the MSD 6010 with the carb, the output wire is designed for the usual tachs.

Glad you found somthign that will work, i hate not having a accurate tach(for the most part, my Autometer cannot keep up with my engine by 300 RPMs in the revs).

 

It seems to respond very well without being jumpy. We'll see how it does at the track tomorrow.

 

For my tach I just ran a white wire from the Red Connector 10 to the yellow wire coming out from the bulkhead on the driver side area. Worked fine.

 

you probably have one of the lower level autometer tachs, i've found in our race engines they won't keep up either and the shift light won't turn on until the motor is on the limiter. Once we stepped up into their expensive tachs the problem went away and it's accurate based off changing the 2 step through the range of the tach operation. A sport comp and autogauge both in my personal car didn't keep up but my phantom tach has no issues nor does the ultra lite playback tach which is $$$$ but super nice to record runs.

 

Well, the tach read dead on the 2-step set point today, so it's close at least in that range.

 

Mine is accurate on the 2 step, but like i said, 300 RPM short at the high end when rowing thru the gears.

 

Some don't play "catch up" fast enough for some of our motors is what I was trying to say, when stationary on a 2 step they are fine, but punch it in gear and sometimes they'll lag a bit. We fix the cheaper cars by setting the shift light sooner and sooner until it "corrects" the problem.

 

Yea, exactly, i have to set the shift light 4-500 rpm ahead of the rev limiter.

 

The PCM was doing the 2-3 shift when the tach was reading 6500 RPMs. And, it sounded like 6500 RPMs. I don't think it's lagging, but I suppose the only way to know for sure would be to have some sort of data logging that was in sync to video of the tach.