VSS wiring path

[RonD]

Yes, that's what I found as well, neutral switch/clutch switch, but OP says no

 

[Lance58]

Thanks, the more I look at it the more I am convinced this is the wrong harness. The LB/Y ohms out at pin 64 on the PCM. Just strange that the only thing not working on this truck is The P0500 no VSS Signal, so speedo and engine fuel mgmt are not working correctly. The LB/Y wire is spliced off to another LB/Y just above the connector shown in my photo.

 

[55trucker]

Something not right there, 2nd time you've made reference to *pin 64*, the input signal is supposed to be PCM pin 58, the ground side is pin 33. One has to be able to trust the wiring schematics.

 

[Lance58]

If I wanted to run a jumper from the VSS to the PCM/GEM/Speedo any suggestions on where to splice in?

Thanks

 

[55trucker]

Do you want to do this as a temp/test approach?

My suggestion to you on that would be to search for the S110/S111 splice point, if you see the blu/y conductor there as well instead of the gry/blk keep following that conductor to see where it (if it does at all) returns to gry/blk. The schematics we sent to you, mine IS the Ford schematic, what Ron sent to you is the same but the Ford schematic states the splice points, (perhaps Ron does have the actual ford manual which states where the splice points are, I've not got that for pre 98), go straight to the PCM as the schematic details to go to pin # 58. I take it that at the GEM pin #9 is the proper pin that the gry/bk connects to? The GEM is under the instrument panel behind the radio.

This will take some time, be patient....

 

[Lance58]

There are gry/blk wires at pin 58 on the PCM and pin 9 on the GEM and pin 1? on the cluster.
The blu/y ohms out on pin 64 of the PCM. I saw this 96 harness on ebay and I can see the wiring on the grey connector that mates to the VSS section and there is a visible gry/blk wire there that mine does not have.

 

[55trucker]

Interesting situation there...
Pin #58 is the correct pin for the VSS, you have something there at pin #58, you just don't know where it goes to (seeing as it isn't visible to see where it is going to), if you backprobe & jumper right from the PCM #58 to the VSS harness connect point will your issue disappear?.......

 

[Lance58]

Update, as I suspected the wiring harness was not the correct one for this truck, somewhere in it's history it has been swapped out for one from a different year or options, either way it was wrong. I bought the one off ebay an installed it today, everything now works as it should Thanks to all for your input, much appreciated.

The offending part

 

[RonD]

Good work

Thanks for posting update and THE FIX

 

[55trucker]

Curious...makes one wonder why the harness was replaced, and somewhat incorrectly.....happy motoring now