no tachometer

I swapped in a 5.3 in my obs
I used a PSI wiring harness with the swap
I hooked the tach wire from wiring harness to the white wire on firewall connector ( c100)

Can someone help diagnose why the tach isnt working?

Mine doesn't work either. I believe this is the solution. I haven't had time to do it yet but it looks like it should work.

http://i204.photobucket.com/albums/b...psxr7vpq0i.png

Quote:

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Originally Posted by Chevydillan

Mine doesn't work either. I believe this is the solution. I haven't had time to do it yet but it looks like it should work.

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NO DO NOT use that diagram. That one is for Autometer Tachs and some aftermarket ones.

Wow thanks. I just bought the resistor. So what is the fix?

I found it once but I cant remember where I saw it. I cant remember if it is in the tune that can fix it or not. If I remember correctly, because I cant find it on my computer. I dont need it for my truck being a 98. I think it was just the earlier ones. I could be way off though. I am still searching for a solution.

You most likely need to change a parameter in the tune . Here is a snap shot from hptuners. The tach resolution needs to be changed to make your tach work. My high and low resolution are set to 3 for mine to work correctly.

Here's what I did

http://i978.photobucket.com/albums/a...ircuit_fix.jpg

Tach can be seen in operation here.
www.youtube.com/watch?v=8pqNuuCdePI

That's what I posted just with a 680 ohm resistor instead of 1000.
Thanks I'll try this one.

What is the difference in the resistors

Besides the 320ohm difference nothing. I think either resister should work just fine I'm going to go ahead and try my 1000ohm this weekend I'll let you know how it works out