What does this go to?

 

One wire coming in is purple and white and the other is white with black.

 

Does the tach work when not accelerating - at idle?

1993 LT1 tach is different than all other years of the LT1. It is driven off the coil, where all other years get their signal from the PCM.

Here's the 93 wiring diagram (courtesy of Shoebox), showing the tach filter (also unique to 93), connected to the coil, and having a white wire that goes to the instrument panel.

http://shbox.com/1/93_ign_system_schematic.jpg

The purple/white and white/black wires are most likely the VATS (PASS-Key) wires from the ignition lock cylinder to the VATS Module. Someone may have done the resistor bypass.

Again, from Shoebox

http://shbox.com/1/vats_bypass.jpg

 

It sits on the one at idle, when u accelerate or rev it acts as if it may go up then drops to zero.

 

What would be my best chance at fixing the tachometer? Anyone have any suggestions?

 

Unless someone owns a 93, with its unique tach feed, unlikely we can offer good suggestions. I've been here 20+ years and don’t recall a similar problem with a 93. I'll take a look at the troubleshooting section of the 1993 factory service manual to see if the problem is addressed. Or you can get the free download of the manual (courtesy of GaryDoug) and take a look:

https://www.mediafire.com/?40mfgeoe4ctti

Logically, the problem could be a defective tach filter, a problem with the tach/instrumental cluster, or a loose wire that flexes when the engine moves under a high torque loading.

 

Thank u ill attempt a download, it doesnt hurt to ask and i appreciate all the input and help i can get..

 

Daron, you ever get it sorted out? I have an issue with mine where it flutters at idle and doesn't rev at all. I'm coil over plug though but it use to work and now it's just flutters.

 

Ive been trying to trace down wires, but im bout to sum it up as a bad tach filter