Install and Aftermarket Tachometer and Tach Adapter (with pictures) - Saturn ION RedLine Forums
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Install an Aftermarket Tachometer and Tach Adapter (with pictures) Install an Aftermarket Tachometer and Tach Adapter (with pictures)

Like many of you, I'm not a fan of the position of our factory tachometer. It's a little difficult to change your view back and forth from the road/track to the tachometer all the way on the right in our cluster. The easiest fix here is installing an aftermarket tachometer that you can position right where you want it.

The first thing I did was mount my new tachometer on top of the steering column where it wasn't obscured by anything. I drilled a small hole in the plastic molding on top and ran the wires through.

This is an Autometer Phantom II Mini-Monster Tach that measures 3 3/4" in diameter, perfect for viewing through the steering wheel. There are 4 wires coming out of it: black (ground), white (illumination), red (12 volt power supply), and green (signal).

I grounded the tachometer up above the hood release lever.

Next I located the wire for illumination. It's the gray wire that feeds into the connection on top of your steering column underneath the molding.

Then, I located the 12 volt supply. This one's a bit tricky... it's underneath here...

The blue wire leading into the green connection under the column is the easiest 12 volt to splice into. My tach didn't come with a fuse on the 12 volt line so I had to put one it. Make sure you do the same to avoid frying your $200 tach.

The final step in installing the tachometer itself is to feed the green signal wire through the firewall. You'll find that your old friend the wire coat hanger is a perfect tool for assisting you through the grommet just above where the driver's feet sit.

Now that we're all done setting up the tachometer, it's time to set up the tachometer adapter. This adapter allows the tachometer to read a true signal off of the coil harness since our car has 4 coils and no distributor. Depending on your tachometer you may not need this adapter. Some tachometers have a setting that will allow you to "tell" the tachometer that it's only reading 1, 2, 3, 4, etc. cylinders. The tachometer I got DOES allow me to do this, but splicing into one single coil's signal made me feel a bit uneasy. With this adapter you're sure to get a true signal from the 12 volt supply to all 4 coils.

First I mounted my Autometer Tachometer Adapter (part number 9117) under the hood away from excessive heat.

There are 4 wires coming out of it as well. Black (ground), gray (signal), red (12 volt ignition signal), and red with either a gray or green line (coil positive).

First I grounded the adapter.

Then I attached the gray signal wire to the green signal wire that we put through the firewall grommet earlier.

Here's where you begin to remember your four-letter vocabulary. This next part is a pain in the ass.

You'll need to remove the coil cover and identify the coil harness.

Follow the harness down the driver side of the engine and you'll soon run into a quick disconnect for the harness.

Make sure to disconnect your negative battery terminal to avoid getting engine codes before continuing.

Disconnect this using a long standard screwdriver by applying pressure to the tab on the right side of the connector. You may need a pair of long needle nose pliers to pull it off. There's not a whole lot of space in there.

After you get it off you'll see that there are 7 wires coming out of it. A green wire w/ white stripe, a red wire w/ black stripe, a light blue wire w/ white stripe, a purple wire, a black wire w/ white stripe, a brown wire w/ white stripe, and a dark blue wire w/ white stripe.

The red wire with a black line on it is the 12 volt coil ignition power supply wire. There's not a lot of space to do this in so be very careful when proceeding. Cut this wire giving yourself space to strip it on both sides. Run the two red wires from the tachometer adapter and splice them as follows: The red wire with green line on it coming from the tachometer adapter splices to the red wire with the black line that is still connected to the quick disconnect. The plain red wire coming from the adapter splices in the red wire with the black line that goes to the ignition.

After you've done that reconnect the quick disconnect and tuck any extraneous wire away from any moving engine parts (shouldn't be too difficult). Now reconnect the negative battery terminal.

And you're done! I ran the two red wires and the signal wire back behind the engine and cased them in wire loom so it looks more tidy. If you have a strut tower brace bar you can cable tie the loom to it to ensure it the loom doesn't make contact with your header (this would be disastrous).

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  #1 (permalink)  
OZERMAN on 03-22-2008, 06:49 PM
very well done
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  #2 (permalink)  
dont_blink on 03-22-2008, 06:57 PM, it's not really. The "ground" you picked is a horrible location and not fully chassis grounded as there is paint all over the place. That nice little blue wire you tapped there handles a 2A current draw at most after being fed through the 2A +12V constant wire feeding that. Better hope that tach never malfunctions because I don't see a fuse on the wire you ran and if you lose voltage through that wire while you're driving...bye bye power. You should be grabbing that from the BCM with a fuse inline.

How did this get stickied again?
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  #3 (permalink)  
secondstringsoldier on 03-22-2008, 08:56 PM
Actually the 12 volt is fused. And the area on the body behind the nut on the ground is sanded down to bare metal. Thanks for being a dick though.
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  #4 (permalink)  
dont_blink on 03-23-2008, 08:35 AM
Really? That ground you picked under the dash has NO paint on the surfaces that reinforcement plate is bolted to? Hahaha, okay. I mean...I've never wired anything into a Cobalt or Ion before, I just do remote starts/security for a living.
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  #5 (permalink)  
secondstringsoldier on 03-23-2008, 11:59 AM
Congratulations. You win.
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  #6 (permalink)  
Crill_Borsby on 06-21-2008, 03:27 PM
nice. good write up.
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  #7 (permalink)  
reppin04 on 06-21-2008, 05:57 PM
damn man way to be a douche up there
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  #8 (permalink)  
bluesat on 04-19-2010, 07:19 PM
this is a great write up man. really nice. by the way, where did you get a hold of the metal hoses for the by pass/evap/intake hose?
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