I just installed the LTCC on my 93 and now the tach doesn't work. I've emailed Bob Bailey but wanted to check to see if anyone here has solved the problem. I've searched and found others asking the same questions but with no solutions posted.

 

There is a separate tach signal that comes from the PCM to the gauge, so I don't know why the LTCC should have an effect on that. The PCM gets a signal from the opti and then sends one signal to the tach and another (on a different wire) to the coil.

 

Do you have a aftermarket tach? Is that the one you are saying isnt working? If so you will need to tap the wiring harness on the ECM. White line, red plug I think. I will verify it tomorrow when it is daylight for you if you want. Or do a search, I have found it on here before when I did my LTCC.

Also, word of advice make sure your LTCC is grounded extra good and they are all clean grounds

Q

 

Thanks guys,
I got a wiring diagram from Bob last night and I'll try it tomorow. It basically says I need to jumper from the white wire of the old ignition module connector to the white wire on the Gray connector of the old coil.

 

Well the fix Bob Bailey adivised didn't work, anyone have an idea how to restore my stock tach function without a stoch coil or module?

 

If your tach worked to begin with, it should work now if you have it wired correctly. I have installed 2 of his LTCC's now and have had no problems. Just make sure that you have the wires where the coil and ignition module are hooked up as you are supposed to on the LTCC. If you want some help, PM me and I'll walk you through it.

Ryan

 

i have a delteq system in my 93. when i installed it, my tach didnt work, so what i had to do was remove the tach filter that 93's have. its a box with 2 white wires and a black wire going into it that is on the wiring harness that goes over the driver side valve cover.stock it plugged in by the coil. i had to splice the 2 white wires together. that might help. -dave

 

Perfect! Your the hero of the day, that was the last piece of the puzzle. Mine was barried under tape along the harness leading to the stock coil. Interesting that the filter was grounding out the signal after the mod.

I guess that's just another unique item for the 93 specific list.

Thanks again for your help!

 

Glad to see you got it fixed.

Ryan

 

Ryan,

Thanks for the help, I think our cars are wired different (I have no yellow wires, and I hook up to a solid white per Bob's instructions)
You never know what's going to be the trick on our cars, lots of variables.

Thanks again.

 

glad to help you. hope you werent trying to fix it for a long tim. i talked with peter from delteq and he had no idea. so i played around with it for a few days and got nothing. all of a sudden i get this email from him, he looked up a whole bunch of wiring diagrams and saw the tach filter there. he said he's never seen that before. hows it run with the ltcc? got any pics? im interested to see it installed. -dave

 

Just did it yesterday, no picks yet but I'll post them on this thread when I do.
I mounted the coils (5.3 Vortecs) to a plate on top of the intake and used Taylor cut to fit wires (ordered the LT1 Optispark boot kit too). I mounted the LTCC on the fenderwell above the fuse box and ran the harness up under the cowl. Everything fit perfect and it looks clean.
I just sent an email to Bob Bailey asking him why the filter interferes with the signal, I'll pass on his responce when I get it.

 

i guess they deal with so many more 94 - 97 cars that us 93's dont get the attention to find the differances.

 

Bob Bailey replied to my question regarding the Tach Filter problem with the following:

"The signal from the coil that feeds the stock tach is HUGE,
the tach filter makes it a lot smaller to feed the tach.

The EST signal (white wire) is only about 4 volts and is
about right for the stock tach without the filter."