Doing a V8 swap on my 98 2wd. Question on the speedometer signal. Using a 99 mountaineer donor 4R70W I know the current signal comes off the rear axle and speedometer worked but since the Mountaineer had 4wabs and the Ranger doesn’t will this affect the transmission. Do I have to run a signal wire to the Mountaineer pcm to get the transmission to shift properly

 

Yes, you will need to run a wire to pin 58 on the V8 PCM(computer)

Rangers used the GEM module to convert rear axle ABS sensor signal to the 8,000PPM needed by speedometer and PCM
Explorers used the 4WABS module to do the same thing

Both used a grey/black wire for this speed signal

GEM module pin1 will have this grey black wire as will instrument cluster pin 1 center connector
You can TAP either of these wires and then connect that jumper wire to PCM pin 58 grey/black wire

 

 

It depended on the YEAR of the Ranger, as to where the "speed" signal came from

1983 to 1997 there was a gear driven speed cable or VSS on the trans or transfer case, shared with speedo, computer and cruise
1998 to 2000 the rear axle ABS sensor was used and converted to a "speed" signal by the GEM Module, shared with speedo, computer and cruise
2001 and up used an OSS sensor on the transmission and it went directly to computer and was then converted, by the computer, for speedo and cruise use

From 1995 to 2000 pin 58 on the computer(EEC-V) was the SPEED IN port, it needed 8,000ppm(pulse per mile) signal like the speedo and cruise needs
1995-1997 the signal was from gear driven VSS, which was 8,000ppm as is
1998-2000 the signal was from rear axle sensor(30,000ppm) and converted by GEM to 8,000ppm then sent to pin 58 on computer, also sent to speedo and cruise

2001 and up, the computer got OSS signal, 20,000ppm on pin 84, then converted it to 8,000ppm and sent corrected signal out on pin 68, to speedo and cruise
Just as a heads up, on many diagrams pin 68 is labelled VSS in, that would be wrong, its speed signal OUT, just FYI

Yes, the computer needs the speed signal to control automatic transmission solenoids(shifting), computer/transmission will still shift without a speed signal but the shifts will be abrupt/harsh, this is called safe or limp mode, its safer for clutches and bands(brakes) to shift this way, so there is no slipping(extra wear)

Not sure why anyone would say you don't need the correct speed signal at the computer on a 1995 and up Ranger, thats silly, you absolutely do, and in a 1998 Ranger that signal is at the cluster, GEM or Cruise, the grey/black stripe wire, so tap that wire and hook it to pin 58 on the computer, which should also be a grey/black wire

 

Great information thanks. The ranger is a 98. I have to swap the tach wire on the IP I will correct the signal wire at the same time. Is there somewhere in the cab to tag the ECM wire or do I need to run a new wire to the ECM

 

I am not familiar enough with Explorer wiring harness to answer that question, but..........................

Explorers used the same Grey/black speed signal wire as Rangers, so look at the connectors on the explorer wiring harness for that grey/black wire, its signal came from the 4WABS unit but can be tied in with the speedo or cruise module wires
On my diagram for a 1998 Explorer V8(don't have other years) I show pin 58 tied to 4WABS connector at S168, thats Splice 168, but have no idea where that would be on an Explorer

But yes, very worst case is you would need to run a wire from a TAP on clusters grey/black wire to pin 58 and splice it to the grey/black wire thats there now, cutting the wire of course

 

Checked the wiring diagram for the 98 ranger with rwabs shows the grey and black wire comes off the gem module and goes to the speedometer and to pin 58 on the ecm that part of the harness is still the original ranger harness so it should work as is. The 4wabs trucks are wired like the explorer comes off the abs module to the speedometer and to the ecm pin 58. Thanks for the information it really helped to trace wiring in the schematic

 

Yes thats all correct, for some reason I don't think its connected when you use the V8 ECM wiring harness