Hot Rod Forum banner

Electronic speedometer question

958 views 5 replies 2 participants last post by  docvette 
#1 ·
I'm planning in swaping a Chevy 350/TH350 into my '99 ford explorer (I'm a ford owner with a chevy heart) my concern is how to make the speedo work after this swap? also the oem tach is for a 6 cylinder, is there a way to make it work for an 8 cylinder?( a jumper or something), if the answer is get a V8 explorer tach it would be very hard to find one here, back to the speedo, doest it runs off the ECM? is there a standalone module for it? the new motor will be carb fed.
Thanks.
Augusto.
 
#2 ·
Doc here, :pimp:

The ECM Controls the Vss, It is Pins 33 , Pink/Orange , and 58 , Gray / Black.

The diagram does not show an output to the dash head unit ..but I'm sure if you follow the bundle back, that's where it will be. Is it an LCD Dash?

You can get a pulse generator for the GM transmission easy enough, but to interface it to the Explorer wiring may be tricky..Do a Goggle search on Electronic Speedometers..there are several places that make the Pulse generators,and may have a pre~Made harness for interface.

The ECM also controls the Tach function, Pin 48 , Tan / Yellow wire ..If it's internal calibration board is set for 6 cylinder , there is not a whole lot you can do..Except replace it with a 8 Cylinder tach.

There is one remedy if you feel up to the task..AND It's a Mechanical Tach..

Get an 8 cylinder aftermarket Tach, Remove the calibration board carefully from inside it, At the back of the meter you will find two wires, + and -, these will go to your stock head unit meter when you switch over. mark them as such.

Go to the local electronics store and get a project box (plastic) that will hold the calibration board. Mount that in the box, drill a hole big enough to get the wires out of in each end..

Remove your stock Calibration board, and extend the wires from your project box to fit inside the stock meter housing, hook up the + and - wires to the stock meter.

Next hook up the red wire from your project box ( aftermarket tach wiring) to switched power , The Black to a good hard ground. Lastly hook up the gray to the - side of the coil..

Tie up the project box with tie wraps to a handy wire bundle, and you have an 8 cylinder Tach, with a stock meter face (no one will know but you.)

Doc :pimp:
 
#3 ·
Doc,
seems like there is ligth at the end of the tunnel, thanks for helping me, just give a little more info.
I understand I'm gonna have to keep the oem ECM hooked up, I guess I must to keep the ABS working and the other stuff controlled by it, well no big deal, I wanted it to manage the V6 motor in whatever project it ends up, it's a nice 4.0 SOHC unit but it just does not have the awsome sb chevy V8 torque and SOUND!!!, getting another unit should be no problem.
But if I leave the ECM in it's place there will be no problem with the speedo since the ford vss runs from the rear axle tone ring, problem solved.
I like a lot your solution for the tach, even if I don't make it work I think I can sneak a new tach behind my dash in the stock location.
Please tell me if I am rigth about keeping the ecm in place.
Thanks again.
Augusto.
 
#4 ·
Doc here, :pimp:

In looking at the diagram for the Ford, (and getting a headache..)

You can leave it (body connected) in place, But It will not control the engine..At all ..

You need to get a diagram to be sure no intertwined systems will disable another and plan around that.. (like no oil pressure shutting off a fuel pump..ect..) So You need to sit and study that before cutting anything.

Doc :pimp:
 
#6 ·
Doc here, :pimp:

Yeah, Get to know BOTH systems in your sleep..or on the crapper as it were..

Make a third Note book for the interface Hookup and Notes as you "Design" the graft. Then go to the Vehicle and lay out your game plan. Get to know what's what, before you graft / Cut ANYTHING..

Take TONS of Digi Photos of routing, wire count , where they are, (make little cardboard Q Cards with Id points on them..like you have a group of wires on the fenderwell, and they go to the charging system, put a Q~Card there that Say's "Alternator" ect..) snap a picture of it..load it up into your hard drive for future referance..You'll be glad you did!

Keep us posted on the project! :thumbup:

Doc :pimp:
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top