Ok so you’re like me and use a tach more than any gauge (I even use it to keep track of my speed). Anyways it took a long time for me to get all this info for this truck and I did it without any help (hours of looking at schematics). Ok I’m not going to give anyone any wires or colors (except pin #48 because I know its standard on all of out trucks) because I have a 98 and I imagine these trucks got more wires and different accessories as the turn of the century happened. Ok one more thing: I shall not be responsible for any pain or damage you bring upon your truck or yourself when attempting this mod.
Ok here’s what You’re going to need:
Tachometer (make sure its calibrated for a 6 cyl. or if you have an 8 to do this look at your tachs manual)
About 30 ft. of wire (different colors help especially if you’re going to be like me and not do the full thing in one day and find yourself doing part of it in the school parking lot after class because by the time you get back home it will be dark lol)
Soldering Iron (I guess crimp connectors will work but I personally hat em’)
Solder (if you’re going to use a soldering iron)
Electrical Tape
Schematic of your truck Haynes manual’s have them
Something to cover the wires (optional just makes it look better)
***Ok I’ve heard that not every truck is wired for a tach in the first place. I was lucky because mine was. I have a feeling that its the 99 and up trucks that aren't wired if they don’t have a tach but don’t hold be to it. To save yourself the aggravation go ahead and go to radio-shack and get a female D-Sub connector and a #30 drill bit and drill because if your not wired for it you’re going to have to make the connector on you’re wiring harness on the computer end I know how to do this and I will give you guys instructions. I say to go ahead and get it because all this stuff costs about 4 bucks total and you can always return it if you don’t end up needing it***
Ok lets begin
First of all find a place to mount your tach I chose on the top of the dash on the far left side. Of course mine is a 5 incher so its a pretty big one. Some may choose on the A pillar or on the steering wheel shaft (my personal favorite but mines too big).
Next first lets get the lights working (Some tachs may not have these). Most tachs its a white wire but check your user manual first!!! Ok you’re going to want to connect it after the dimmer on you’re light switch (look at you’re schematic).
Ok lets hook up you’re 12 volt power wire (usually red) just look it up. You’re going to want to hook that up to a power source that is only on when the key is on (I used the radio).
Next the fun part, the wire that tells the tach what the rpm is (aka. pin #48). Ok run your wire (usually green but again, look it up) down to the floor on the driver side and look over above your flooring and you’ll see a patch of the flooring thats against the firewall that lifts up (auto trans your shifter cable runs through here and you can locate it easily by following it). Ok lift the patch and you’ll see a black grommet. poke your wire through the grommet and open your hood. Look down and you will see the wire poking through the grommet. Run the wire up and find some way to hold it up (look at the pic for a pretty good example). Ok your going to want to run the wire across the top of the firewall. Once you get it across there take your battery out and remove the tray (trust me you need all the space you can get). Ok once you got all that done look at your PCM (Powertrain Control Module) and locate pin #48. Ok for the nope I put up above By now once you locate pin #48 you’ll know if your truck is wired for a tach or not. If not ignore this and read down to the next paragraph. ok if you were like me and got lucky with the pin your going to have to extend the wire a little bit because its really short. Ok cut the wire that leads to pin #48 (you’ve just ruined you’re truck... jk lol). Now cut yourself a few inches of wire enough so you can work with and cut that piece in half. Now connect one half of that piece to one end of the wire that pin #48 is connected to and do the same to the other half with the other side of the wire. Now twist those 3 wires with the wire that leads to your tach and secure it with solder or (I hate saying this) a crimp connector (quite frankly I don’t recommend this). Congrads you’re almost done if you were able to do this you can skip this next paragraph.
(see the 3 wires fused together, the green one leads to the tach, and the black is pin #48)
(thats the harness connected to the PCM)
Ok un-lucky people, you’ve got yourself a PCM that needs to have a pin put in... Ok first locate you’re PCM (Powertrain Control Module) and find the bolt that holds the harness end to the PCM. Un bolt the bolt and take the harness apart from the PCM. Ok now locate where pin #48 should be (should be a # engraved in next to the circle where the wire should be coming out. Ok locate the hole (and make sure its right) and drill the circle area with the bit I told you to get. Ok now get a D-Sub connector and attach it to the wire that leads to the tach. I HIGHLY recommend putting a little solder and electrical tape on the connection to make sure she don’t come loose. Ok lead the connection and wire through the hole you drilled on the harness and plug the connector into the copper pin #48. Ok now bolt your harness together and start you’re truck to make sure you did that correctly (you’re tach won’t work yet).
Ok now the last part the ground. Should be a black wire (check). Ok run it down through that grommet where you put the tach wire and go back to under the hood. Locate a ground post on you’re firewall and loosen the bolt a little. Place the end of your ground wire under the bolt and tighten.
What are you waiting for? Test that thing out. If it works congrads your tach works. If your tach has lights turn on your lights and your tach should illuminate.
Enjoy!!!
If anyone has any questions post them I will get to you asap. Better to ask now then get stuck without a truck later. Also if anyone has any comments or corrections I need to make post them.
Aftermarket Tach install
Linear Mode
