j_martin

Pin out and color codes should be on this page.

Redtruck-VA

That's great. I have the 89 service manual but that didn't help me with this.
YL- 8vdc
BK/LB - GRD
GY/PK- CKP pickup

Thanks,

Redtruck-VA

This install is going really slow. I keep getting side lined. I have all the bits and pieces I need. Got the Tach physically mounted, had to get another longer cup to fit the tach and then modify it. The 25 year old plastic molding is brittle and I had to be very careful not to break it. I couldn't locate a female plug so I guess I'll cut off the plug and simply splice it together. Any way I'm getting it done slowly, heres a picture of the mounting.

thrashingcows

I like the Tach...has a bit of a retro feel to it.

Redtruck-VA

Thanks, I too like the retro look, especially in the old girl...

w250 guy

Really like the looks of your setup, unfortunately i cant justify not using the isspro tach that i got for free! Maybe somewhere down the road ill upgrade and dig up this thread [cool]

Redtruck-VA

I've received the female end of the plug so I'm going to try wiring it up today.

Redtruck-VA

Wired it up and tested it. It idles at 600 rpm, revs to above 1000-1500 then drops to zero. Let up and it goes back to showing idle. I'm thinking it is losing signal, probably the gap is wrong. Anyone have similar problem?

Redtruck-VA

Reset the gap a couple of times both a little on the tight side and at .050. Voltage is 8.3vdc. Idles at 600 rpm, looks solid. Raise the rpm up and it looks good until 1300 and then loses signal and the tach drops to zero. Lower rpm and it re-sync's. Anyone with any ideas?

j_martin

What voltage is at 8.3v? If you're using a stock CPS, 8v would be supply, output goes between 5V and near ground (usually about 0.3v).

Does the Tach match the application?

Redtruck-VA

Jim,
This is lashed together from pieces I bought. OEM harmonic hub and pickup. 8vdc supply from a zener and the signal output straight to a SW tach set to two PPR. No pmc installed. I don't have a Oscope so really don't know what the signal looks like. Works up to 1300 rpm and then loses sync.

j_martin

I suspect the tach is looking for a wider pulse by about 5:1 of what it's getting. It would help to have some specs for the tachometer. Also, what's the supply voltage at rpm when the tach fails? Maybe I guessed the wrong resistor value.

Redtruck-VA

The voltage is stable, I'm guessing you are spot on with the value. The only spec sheet I have found is the setup sheet. But the symptoms looks to me to be signal loss.

http://static.summitracing.com/globa.../sww-82620.pdf

bradshaw106

You need to hook up a oscilloscope and watch what the signal is doing.
Have you tried just feeding the cps 12v? It's just a hall sensor. Just a thought.

j_martin

The stock CPS is normally supplied with 8V from the PCM. I believe internally it's further divided or regulated down to 5V. 12V might burn it out.