??Need help installing aux. tach??

[nuc]

I'm attempting to install an A pillar tach. Hookup went fine, all the connections tested out (ground, power, light) but when I tested it. Nothing happened, no needle bounce, nada. The only thing I could see was that maybe it wasn't getting a signal from the 2 wires with the green connector behind the alternator. So I tied into one of the wires itself, still nothing. I took the dash out along with the factory tach. and touched the wire from the aftermarket tach to the white wire coming into the factory tach. still nothing. Double checked the power, ground, etc. no problem, so maybe the tach is bad.

I take out the trusty 3 cylinder Geo, hooked it up and no problem, works right away.

Is there anywhere else that I can hook up to in the GN for the tach signal? Or is there a way to test if I actually have a signal at the green connector behind the alternator?

Thanks in advance

 

[BLACK6PACK]

There should be just one green wire behind the alt. Did you cut the proper wire so that it would work with a 6 cyl car?

 

[BobbyBuick]

if it is a vdo tach.you need to send it it for a mod about 60.00 or you can do it yourself as i did .you need to add a resister( The 1/4 watt 10K ohm resistor did the trick. The price at
Radio Shack is now 59 cents for 5.........inflation)from the signal wire to the power wire.also i put a diode in so it would not back feed to the origonal tach as it was making it read funny.
the mod I did the vdo people said was not supported however mine works and its 2 years later .theirs never did.vdo used to do the mod for free .now they send you to someone.i forget exactly but i think it had to do with reading a 5v square wave signal that their tach doesnt read

 

[nuc]

Thanks for the quick reply, but I don't have a VDO gauge, just a cheapo 2 1/16" one from JC Whitney. Is there a particular brand 2 1/16" gauge that I need to get that will plug and play? I always thought that hooking up a tach was pretty straight forward.

Power, ground, light , tach signal

Thanks

Also the tach that I have has a switch that allows it to be used with either a 4-6-8 cylinder vehicle

 

[JerseyGN]

Another option if using the VDO is to get the VDO Converter Tach Module from Caspers-102007. Cost is $30 and it worked great for me.

Dave

 

[nuc]

Black6pack,

In regards to the one green wire behind the alternator, I thought the tach signal was taken from a freely hanging green male connector behind the alternator that had 2 off white-ish wires connected to it.

Thanks

 

[BobbyBuick]

I justed edited my message showing the resistor size.Last time i looked JCwhittney never made anything.I bet its a vdo and its the ol 5v sq wave nightmare.autometers plug and play

 

[jsta6]

resistor mod

Bob,

To do the VDO tach mod, just put the resistor in line between the 12v+ and the tach signal wire from the ccci?

Like this:

http://bellsouthpwp.net/s/h/shawnco/projects/tach mod/tach mod_frame.htm

 

[BobbyBuick]

yeas I also installed a diode in the green signal wire behind the resister to keep it from backfeeding to the origonal tach in the dash now they both work

 

[jsta6]

Kewl.

Sounds simple enough...

 

[jsta6]

no worky!



wtf? any ideas?

 

[jsta6]

I don't think that I got the right resistor. The bands look like they are wrong. Like I have an orange band, where it should be black...Does radio shack every screw up their packaging?