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lownslow
06-18-2005, 03:56 PM
i recently purchased an autometer 5" tach with an external shift light, i have one proplem. the green wire coming of the tach goes to the tach signal wire. so i looked up my car on my omega wiring disc we have at the body and performance shop i work at. it said that it that the tach signal wire is a white wire located at the pcm. so i took the top part of the dash off so i can access the pcm, but there is four white wires. i know that the green wire cannot get connected to twelve volt source,which three of the wires did. i connected the green tach wire to the white pcm wire that i thought was correct, but the tach is not working proporly.when i rev the car,the factory tach will be for example at 1500 rpm. now the autometer tach will only read 500 rpm. that is where i am having problems. i wanted to know if i have the right white wire or if i dont do i need to connect it to another one of the 3 white wires on the pcm so the tachs read somewhat similar. or it could be possible the diagram i used was wrong. if so, i need to know what wire is the tach signal wire. any help at all would greatly be appreciated.

wolfman
06-18-2005, 06:23 PM
Easier: Use the white wire at the DIS module under the coilpacks. Though why you are installing a tach on a car that already has one is beyond me.....

ssicarman
06-18-2005, 11:00 PM
Is the aftermarket tach is set for 4 cylinder?

lownslow
06-19-2005, 12:02 PM
Easier: Use the white wire at the DIS module under the coilpacks. Though why you are installing a tach on a car that already has one is beyond me..... i tried that,but the same problem occurs. and to answer your question, im installing it because factory tachs are nortorious for being wrong. that and i want to get rid of my gauge cluster and put a 5" speedo and tach in its place.

lownslow
06-19-2005, 12:05 PM
Is the aftermarket tach is set for 4 cylinder?
yes i have it set for a 4 cly. the tach comes with an orange and brown wire loom on the back of it. if you cut both of them it set for a 4, leave the one uncut it is set for a six, leave both of them uncut for an 8.

eljefino
06-19-2005, 04:52 PM
It seems the tach signal pulse from the dis module to ECM is less than one pulse per spark per cylinder. As it's not expecting to have to feed an aftermarket tach, it could be however saturn felt like setting it up.

Aftermarket tachs are generally only good for cars with one coil, (and a cap and rotor) not cars with DIS.

Luke
06-20-2005, 08:27 AM
> El Jefino <
> Aftermarket tachs are generally only good for cars with one coil, (and a cap and rotor) not cars with DIS <Interesting point.

lownslow
06-20-2005, 11:01 AM
there is probally a way i can do it, but gotta figure it out. the tach was just taken out of my boss's girlfriends maxima. and that has a coil pack for each cylinder. which is a harder setup than what mine is.

mars_volta
06-20-2005, 12:53 PM
the REF HI (D12) on OBD I is for the tach signal.

http://www.differentracing.com/tech_articles/images/j1-01.jpg

lownslow
06-27-2005, 03:23 PM
i tried the tach signal no luck. i think im gonna just put the shift light in. on a better note i picked up a rear disc conversion for $12.00 and a spare tranny for......$1.00.

LUNCHBOX
06-27-2005, 09:37 PM
i tried the tach signal no luck. i think im gonna just put the shift light in.

That's your best bet IMO. I think a 5" Monster tach in Saturns, Hondas, etc.. look foolish in such a small dash. I run just an Autometer shiftlight in my 93SC and spliced into the wire that Wolfman described under the coilpacks with no problem and it works great for almost two years now. I know the engine by sound and all I need is the light for reminder if I get to redline, it's all you really need. I left it with the 3k pil that was in it and just set it to 8cyl and it will light at 6k, wich gives me plenty of warning before redline. I use it on and off the bottle with no trouble AND only have a small black tube next to my a-pillar instead of the monster tach.

Just my .02, good luck with whatever you choose.

dixonba
06-27-2005, 09:54 PM
do tell where you got a spare tranny for $1

lownslow
06-29-2005, 04:23 PM
That's your best bet IMO. I think a 5" Monster tach in Saturns, Hondas, etc.. look foolish in such a small dash. I run just an Autometer shiftlight in my 93SC and spliced into the wire that Wolfman described under the coilpacks with no problem and it works great for almost two years now. I know the engine by sound and all I need is the light for reminder if I get to redline, it's all you really need. I left it with the 3k pil that was in it and just set it to 8cyl and it will light at 6k, wich gives me plenty of warning before redline. I use it on and off the bottle with no trouble AND only have a small black tube next to my a-pillar instead of the monster tach.

Just my .02, good luck with whatever you choose.

thanks for the info. i was thinking of doing that ,but wasnt sure if i had to use the same wire.

lownslow
06-29-2005, 04:25 PM
do tell where you got a spare tranny for $1

at a junkyard called harrys u pull it.it was 25 bucks to get in and a dollar parts.they run that special every now and then.