Tach issue

[larrym]

Alright before I rip it out and take it back I purchased a Proform tach for the Buick, hooked it up and it does work sort of.......... as long as the revs are above 1400rpm it works fine below that it jumps to about 5000 rpm then to 0 until the rpm is over 1400 again, if I hit the memory button it climbs to 11000rpm. I know its a POS but I liked to look it matched the other gauges I have got any ideas before I replace it?


http://www.proformparts.com/product-exec/product_id/820/nm/SLIM_DESIGN_5_INCH_11_000_RPM_RACING_TACHOMETERS_W_MEMORY_/category_id/296

[gusszgs]

Maybe they'll exchange it out for another one. Any warranty left?

[Steve Wood]

sounds like it is confused by the distributorles s ignition to me.  You might ask them if it needs to be modded in order to work with our cars like some of the VDO units do-something about a square wave mod as I recall

[daveismissing]

Didn't John make an amplifier for some apps? ( or was that vss?).
Maybe ask them?

[larrym]

Thanks gents its back to the store with it I think the tech line said I could try a zener diode with a rating of 10 or more?? Or return it for an exchange at point of purchase.


The instructions had the GN covered and explained where to tap into the tach signal so i think its compatible.

[Steve Wood]

I know that some used a diode in the line on the vdos

[Scott87]

I had a similar problem with my Tach. It would work fine but once driving around the needle acted as possesed. I read somewhere it had to do with a weekened signal from the ignition control.
I replaced the coil pack and controler, added a caspers ignition hotwire. I replaced all three at once so the hotwire was probably not necessary.
 
 

Alright before I rip it out and take it back I purchased a Proform tach for the Buick, hooked it up and it does work sort of.......... as long as the revs are above 1400rpm it works fine below that it jumps to about 5000 rpm then to 0 until the rpm is over 1400 again, if I hit the memory button it climbs to 11000rpm. I know its a POS but I liked to look it matched the other gauges I have got any ideas before I replace it?


http://www.proformparts.com/product-exec/product_id/820/nm/SLIM_DESIGN_5_INCH_11_000_RPM_RACING_TACHOMETERS_W_MEMORY_/category_id/296