Tach Wire Location

[Ciera91]

I might need to tap the tach wire on a 91 Ciera 3.3 and wondering if anyone knows where under dash or under hood it might be? Possibly with pictures? Thanks

[Keiths1976]

My friend you should be in luck those years 90-93 have it built in the harness that plugs into the cluster out look at the harness plug should be a white wire

[Ciera91]

Shit another diagram I found says purple white or white at the coil packs. I ran a wire To under the hood before I seen this haha. I found a diagram for remote starts that said it’s purple with white or white.theres a purple with white and 2 white wires at the coil packs/icm harness

I’m going to try the purple/white wire first tomorrow. Wish me luck Keith haha.

[Keiths1976]

It’s white man atleast on the 2.8-3.1 v6 motors gm don’t change wire code colors

[Ciera91]

Keith finally found my FSM. 121 White to Tach. 430 Purple/White High signal. You were right.
I’m trying to hook up a Tach sending wire from a remote start I had installed that the installer didn’t hook up, they used voltage sensing which is probably fine on new cars, but mine needs just a little longer crank time and the tach wire has to be hooked up to do that.

[Keiths1976]

I have a tach on my 95 century I used the power ,ground and dimmer wire and ran it off my radio harness no issues 3 years and going . The 94-6 a-body deleted that harness to the cluster for the newer 3100 v6 and newer cluster so no tach wire was present had to improvise tho and run one off the ignition control module .

[Century7667]

I have a tach on my 95 century I used the power ,ground and dimmer wire and ran it off my radio harness no issues 3 years and going . The 94-6 a-body deleted that harness to the cluster for the newer 3100 v6 and newer cluster so no tach wire was present had to improvise tho and run one off the ignition control module .

Has it been 3 years already?

Wow!

Ken T.

[Keiths1976]

Yup sir 3 years

[tlc1976]

I have a tach on my 95 century I used the power ,ground and dimmer wire and ran it off my radio harness no issues 3 years and going . The 94-6 a-body deleted that harness to the cluster for the newer 3100 v6 and newer cluster so no tach wire was present had to improvise tho and run one off the ignition control module .

I did the same thing when I put a tach in my 89 Celebrity back in 2003 and it still works fine. GM deleted the Celebrity tach harness after 88. I actually made up a custom tach out of 6000 parts.

[Keiths1976]

Tlc u have to find us on Facebook group on a body I’m Keith I can show u my set up since pictures are hard to post here

[DustBro]

Sorry to bring back the dead with bringing back this thread but I myself have been looking to install a tach on the 94 ciera. It's 3 am here and I got woke up by a screaming kid so I'm a little fuzzy but I'm not far off on assuming Keith's 95 century is basically the same as mine, and maybe I should just message you privately but im sorry are you saying you ran a tach off your head unit wires?? I'd love to get a quick run down on that from you at sometime sir, as this would be my first tach install.

[tlc1976]

The head unit is just a convenient place to get the power, ground, and lighting. The white tach signal wire still needs to come from the ignition module if it doesn’t have it already in the cluster. It’s been 20 years (and mine still works great) so I had to look. On the ignition module end it’s a black and white wire you would tap into. On the large 6 pin connector on the module, it’s pin C. One of the middle two wires. I just drilled a new hole through the firewall and wrapped it with a few layers of tape and sealed it with RTV.

[Keiths1976]

Basically that’s how I ran it I ran a tach wire from the icm as tlc1976 mentioned . I borrowed the radio power ground and dimmer ability so I could use the dimmer for the whole gauge cluster at once . I only wanted one wire to the icm so I took the gas pedal off from the interior only two bolts and a cable connector from the throttle body cable and drilled a 1/4 hole into the firewall close enough so I didn’t need 10 ft of wire and hated how people ran it thru the drivers door jam . I soldered my own harness connector for 4 wire leads I have some old pictures I have to find I will post . If or when they load up so I can unplug the tach and replace it by a harness connector . I went to a local junk yard and found any gm with a tach and looked for the white wire in the harness to the icm and used a paper clip to release the connector from the harness and pulled the wire enough length that I needed I was able to pull 2.5 feet from a 2000 Buick century 3100 so it’s color coded to mine

[DustBro]

Phenomenal! After I figure out my hard start its on to a tach! Thanks guys! I thought it sounded awful odd that radio wires would be running a tach haha

[Keiths1976]

Lol haha yea u will see when u get one and have red black white and green wires . I upgraded to a digital one from Amazon that was 19.99 cause the sun pro failed on me and I could get another one