I have installed shift lights on both the 2005 and the 2006 Corvettes and when I went to install the shift light on the 2006 I found that the computer had been changed. Before I go to install a shift light in a 2007 I was wondering if anyone knew if they had made any changes to the 2007 from 2006 as far as which wire is the tach wire? Any help is greatly appreciated.

 

I was told by both a knowledgeable tuner and a software editor that the ECM is unchanged from 06 to 07. TCM is a different story. I wish they would hurry up with those manuals! Chevy parts/service may be able to help. They're supposed to have online access to info.

 

2005 is different than 2006/2007. 06/07 use the new ECM.

 

Thanks alot guys!

 

Shockerracing.com - C6 Corvette Shift Light Install

Tools Required:
- 10 mm socket and ratchet
- 7 mm socket
- ½ socket
- T15 Torx Socket
- Flathead screwdriver
- 25 feet 20gauge wire
- Butt connectors
- Something to poke a small hole through a rubber grommet(I used a small Phillips screwdriver)


Step 1 – Start out by removing the battery from the vehicle. This will help for later on when you are running the tach wire to the PCM. To remove the battery, disconnect the positive and the negative cables using a 10mm socket. Then there is a rubber hold down piece holding the battery in place that you will need to remove using, I believe, a ½ socket. Once this is removed lift the battery carefully out of the car.

Step 2 – I chose to mount my tach on the gauge cluster to the right of the steering wheel as shown in picture A. All of my wires were run up under the steering column and between the gauge cluster and the plastic trim ring around the gauges. To run the wires neatly you will want to remove the plastic panel under the driver side dash. To do this you will need to unscrew the two T15 Torx Screws as shown in picture B.

A.

B.

Step 3 – Once you have removed the panel under the driver side dash and tucked the three wires from the tach down through the gauge cluster you should have them hanging out under the dash. There are three wires that you are going to need to connect: 1- Power 2- Ground 3- Tach Signal Wire. I ran all 3 of these wires through the dash under the Radio and was able to just push these through pretty easily and out on the passenger side. Once on the passenger side you will need to remove the floor mat to reveal the fuse box. The fuse box is under the carpeting on the passenger side, so you will need to pull it back to reveal the fuse box. I neatly ran all three wires under the carpet and over to the fuse box. I connected the ground wire to the screw you can see in picture C with the pink wire connector. I believe this was a 10mm socket to remove this screw and this gave me a good ground. EDIT: I have since moved the ground wire to a ground under my center console because the one I initially show here stopped working. The power wire will need to be connected to a fuse in the fuse box that only receives power when the ignition is on. I used the 10a fuse that is marked wpr/washer and is located to on the right side of the fuse box underneath a plastic cover. This was the only fuse I could find in the whole fuse panel that had keyed power. You may have other options for keyed power depending on your vehicles options. Picture D. is a better pic of the whole fuse box and the fuse I used is under the black plastic cover which is located under the blue plug.

C.

D.

Step 4 – Once you have the power and the ground hooked up you will need to get the tach wire through the firewall and into the PCM. This is the most difficult part of the install and also the reason why I removed the battery before doing anything else. Under the dash above the fuse box is a large cluster of wires that goes through a large rubber grommet through the firewall, I tried to pull the tach wire through this but was not able to so I ended up pull the grommet out into the engine bay. I then made a very small hole in the grommet and pushed the tach wire through it. I then pushed the grommet back into its hole (this was much easier with a friend to help under the dash while I pushed from the engine bay). See Pic E to see the wire cluster from the engine bay. Now you will need to access the PCM which is located below the battery tray and is accessed through the passenger side front fender well.

E.

Step 5 – NOTE: This paragraph is for the 2005 C6 only for notes on the 2006/2007 see the paragraph below this one. Next you will need to remove the plastic wheel well located at the back of the passenger side front wheel well. You should be able to remove this by turning the wheels all the way to the right but I just removed the wheel to have it out of my way. This plastic panel is held on by 6 plastic push pins see picture F. To remove these push pins pop the head out and then pull the whole pin out of the hole. I used a flathead screwdriver to get them started then pulled them out by hand. Once those are all removed there are 3 screws located underneath the car – two 10mm screws and one 7 mm screw. Once these are all removed the panel will come right off exposing the PCM. When you look at the PCM there a 3 Connectors of wires that are labeled J1,J2, and J3. J3 is the top one, J2 is the middle and J1 is the bottom one. J1 is the one we need to tap into. Picture H. shows the PCM with the cover off of connector J1. You will need to take the cover off of J1 carefully. To do this pull the red safety plug out and then you will be able to slide the black cover over and off exposing all of the wires and the pin numbers. The tach wire is a white wire on pin number 48. With the wires exposed you will see the number 43 in the upper right corner and the number 56 in the upper left corner. You will want to count the pins over from either side until you count to 48, it should be a white wire that is six over from the number 43. I cut this wire and used a butt connector to connect the wire from the shift light into the pin 48, try to make your cut as far away from the PCM as possible to make it easier to work with. Then after I connected it I taped it all up neatly and put the connector cover back on.

For 2006/2007 Corvettes they have changed the computer. There will be only two connectors to the computer and they are labeled J1 and J2. The tach wire is still located in Pin 48 in the J1 connector which is the bottom one.
For the 2006/2007 the J1 connector will look like this:

32 .................... 52
53 ....................72

You need to count back 4 pins from 52.

F.

G.

H.

Step 6 – Once all of your wires are connected you are ready to put all of the panels back together and make sure everything is put back together cleanly. Then you can replace the battery. You will want to set your shift light to a low setting to test that it is reading properly. I used 2500 rpm and revved it up to be sure it turned on at 2500. This last picture is a pic with the shift light lighting up. Mine is a Harlon shift light but most other shift lights should wire up the same way.

I.

 

thats great information. Although I remember in my 02 Z06 I was able to tap into a tach wire right under the dash of the car. Access was through the driver side knee panel. I had to wire all the way to the PCM on my LS1 Trans am, but My Z06 had the tach wire, and the hot when in the ON position wire all under the kick panel. I would assume that a wire has to go directly to the tach, does anyone have any more information about this. Thanks

 

Yes there is a tach wire under the dash. Finding a switched power wire that is not dependent on the headlights is another story - we could not find one. We ended up tapping the fuse for the heated seats in the passenger side fuse box. My buddy wanttospeed hooked mine up so I don't have further details, perhaps he can chime in. I'll PM him.

 

 

Great write up and pics. We need to get the forum moderators to start putting all these great install threads in one place.