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 – 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.

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.

 

where did you get that and how much was it.
i had a shift light like that in my F-body and can not remember where i got it from

 

Mine is a Harlon Shift Light. $50 plus shipping, I have had mine for a long time.

http://www.harlan-engineering.com/store/store.html

You can also check out the Raptor Shift Light from Raptor Performance, it is a little more expensive but it is smaller and easier to program.

http://www.raptorperformance.com/

 

Great write up and you did a good looking and clean job.

 

I don't know for sure about the LS2, but the LS1 tach signal was cut in half. In other words, you had to set the tach itself as if it was connected to a 4-cylinder.

Nice write-up

Dave

 

Thanks for the great write up

 

How well can you see the light looking straight ahead in day light?

 

Seriously, do these things serve any purpose that the tach does not? I've never used one and can't imagine waiting to shift until I get a surprise flash of light as opposed to anticipating the shift while looking at the tach. Someone please splain. Thanks

 

No problem guys! As far as the tach signal goes my shift light has to be set as if it is only 4 Cylinders like Dave said, but each shift light should tell you how to set it.

 

Nice install, but the HUD already has a large shift light built in when in Track Mode. Big-ol up-arrow right before red line.

 

Mine is a base model, that does not have HUD. Robvuk, I like it because I set it just before I want to shift and then you can use your periferals to see the light and know when to shift, rather than looking at the tach while you are racing.

 

Oops, sorry - forgot the HUD is not standard. Also, the LEDS in the aftermarket shift light are undoubtedly better, especially if using peripheral vision and in bright sunlight.

 

Yeah, I can see mine pretty well during the day. It is kind of shadowed in the gauge cluster so it should even be ok with the glass top out.

 

With the heads up display are you able to set the shift light to your desired shift point?

 

i just installed my shift light tonite....i mount it on top of the A pillar and route all the wire to the underhood fuse box and got power ground and tach signal from there....i didnt have a camera at my shop so couldnt take the pictures....i'll post it in a day or two
so what rpm did you set yours at?

 

I haven't set mine yet, I gotta pull out my dyno sheet to see what to set it at. Right now it is still set at the 6500 rpm I used for my ZO6, but that is way too high for this car! What did you set yours at? Where did you get your tach signal from KrazyC6?

 

HUD only has that for the 6-speed manual; unless I really haven't been paying attention. I'm about to put a shift-light in my A6 paddle shift.

 

right now i have it set at 6300.....i connect all three wires to the harness under the engine compartment fuse box....open the box u'll see four bolts unscrew those then u can remove the fuse and relay box then u'll see four harness under it....all the wire can connect to the white color harness Pin A1(power B+ switched-yellow) Pin D1 (Ground-black) and Pin D8 (Tach Signal-White).....the ten feet cable on the light just makes to the fuse box

 

Nice job, thanks for documenting this

 

KrazyC6, are you saying you can get the Tach signal from under the fuse box in the hood rather then the PCM directly ?

-Sean