hi i have a 99 f150 xl 4x4 4.6l . i have no tachometer b/c it is xl but it does have a digital odometer and ive read on another thread that u can hold the trip button and turn the key to the on position..wait 5 sec or so for it to say test..then let go and press untill is says tach0000.then w/out turning the key to off start the truck and you will have a digital tach.problem is u have to do this everytime u turn the truck off!
i would like to hook up and aftermarket tach!!

SO MY QUESTION IS..is there an rpm signal wire i can use for an aftermarket tachometer going to odometer.and what pin number on computer would it be so i can chase the wire..thus removing the need to mess with the computer.

any help would be much appreciated..thanks!!

 

Go junkyarding. Buy a gauge cluster with a tach. Plug it in. Happy time!

 

i was told i had to go to a dealer and it would have to be flashed or sumtin to read the right mileage..in another words cost money.. i could have an aftermarket tach installed in an hr if i knew where to get the signal from and had a $100

 

------>Installing a tach<------

there ya go. check that out and see how it goes

wait..that was done on a 4.2l....oops. let me look harder....

Here is a PCM pinout for the 4.6l pin #48 is your magic pin --->PINOUT<---

 

that does help a lil but that diagram is for a 96 from what i can see..

the fact that a 99 uses a digital tach in the odometer i wonder if it uses pin 48 for the signal?? i really would like to see the diagram for a 99 4.6

 

no. anything with ** next to it is built AFTER 6-24-96...anything with *** is built BEFORE 6-24-96. anything without something next to it, is unchanged.

 

General background info you need to know about tachs.
.
The old style single wire types use a single signal from a single coil switching to count revolutions and average the response on an analog meter.
On these motors you either have two seperate coils for 8 cylinder or 8 seperate coils depending on year and motor.
Problem is obtaining a single point that "accurately" will represent the actual RPM on any given meter display.
The factory display is designed to use a signal directly from the PCM not a coil circuit.
The crank sensor is actually a tach pickup to tell the PCM what the crank is doing as a reference only for all other functions the PCM has to address.
The dash display of RPM is only a temporary display because powering down resets all dash functions except mileage each time the ignition is turned off.
MSD may have an adapter to accomplish an easier aftermarket Tach function install.
Good luck.

 

...used the single tach signal wire on my 04 civic. I know its not a f150, but same instance, worked fine and the tach read properly. Dont really think an adapter is so needed. Mb Sscully can jump in, he has a great electrical understanding of these trucks.

 

thanks for all the advice..but i guess noone actually knows the exact place to get the signal..ill try and figure it out and keep it posted!! thanks guys

if anyone has anymore info i would much appreciate it!!

 

$75 and an hour gets you an OEM one installed