Banging my head , yep that's me!

HSW dry kit with Harlan window switch. I've been though the wiring several times already, it all appears correct but something's not right. If I take the window switch out of the loop it works fine. With the window switch wired it appears to be shorting my tach, dash tach falls to zero. If I remove chasis ground from the black wire on the window switch tach starts working again.

On the window switch I've got 12V switched to the red wire, chassis ground to black and tach signal (blue connector, pin 35) to green. White to relay pin 85 to provide relay ground. The white wire is described in the instructions as a second black wire but there's only one black. The other three wires (red/black/green) are bundled together.

Anyone got any thoughts on where I should be looking?

 

By the way, this is my son's car not the Z. Blue connector pin 35 is right wire for tach signal on 98 LS1.

 

Its been a while since i had my harlan window switch, but i believe the white wire is the switched ground. The white wire should be hookup up as the ground of the switch side of the relay. You dont have the white wire in addition to a ground wire on the relay do you?

 

Just one ground going to relay terminal, it's from the white wire on the Harland.

Just did some additional testing, I think it actually is wired correctly and working. The tach is still not working though. Maybe I've got grounding issues for the tach? It seemed to be a little eratic at higher RPM. Maybe hooking up the window switch is just making an existing problem worse?

 

Our cars can be very finicky when grounds are added. One thing you might try, your new additional grounds, unhook them , then jumper em to the batt directly, this may help? You sure you have the tach wire going to the correct wire? Could be an internal short in the WS? Good luck
Robert

 

Grounds are always the most fun to trace down aren't they

The window switch is working correctly as is the WOT. I tied the window switch back into the circuit and lowered the low RPM to 2k to test. Works like a champ on the low end. I assume on high end too but didn't lower the high setting tonight and didn't rev it high enough to hit the current setting either.

This is a conversion car, 88 TransAm GTA w/ 98 LS1 & 4L60E. We did all our own wiring for the conversion so maybe I didn't get one ground quite right. I'm going to have to dig out the wiring spread sheets and try to figure out where the tach get's it's ground. I'll try running that wire back to battery ground and see if it fixes the problem. I'm pretty sure it's a ground issue at this point so just need to track it down.

Thanks for trying to steer me in the right direction!