TexasTechTA

If I can pinpoint where this is I can figure out ym electrical problem. thanks

shoebox

The tach is connected to the PCM on pin 13 of the red connector (C1). Where does it get the info to provide the signal? The opti, of course.

TexasTechTA

the signal for the tach in the opti is it high or low resolution? I thnought the tach ran off the coil.

shoebox

I believe the pcm uses both high and low for spark determination.. The tach is driven off the pcm as stated earlier.

Fastbird93

The tach gets it's signal from the coil, and through a filter that's taped to the wiring harness right next to the coil, then straight to the tach.

TexasTechTA

thanks I just want to know which one it is shoebox says the tach runs off the opti and pcm and you say it is the coil It hought it was the coil but shoebox said no does anybody know 100 percent?

TexasTechTA

I think i? figured out wehy the car is hard to start and the tach went out when i did the comp test on my car I did not pull the ign fuse so the spark from the coil shorted the wire on the coil that goes to the tach which connects to the otpi. so the high res is ogne on the opti. does that seem possibler I do not have an olmeter to check but I am taking it in tomm shoebox what do you think?

shoebox

Looky here and find A13 (tach output). It goes from the pcm to the tach.

The coil also gets it's firing signals from the pcm (see B5 [ignition control] at the bottom of this diagram.

There are no wires from the coil to the tach that I can see.

Then again, a 1993 might be different.

Fastbird93

93's may be then. I just had the service manual out and was looking at the wiring schematic because I'm trying to figure out my tach signal problem. Sorry to cause any confusion.