rockmike

I was trying to get my speedo to work this weekend.I just bought this truck last week and the speedo dont work,the previous owner said they took it to a repair shop and they told her it had a failed part and the part was $100.00 so the owner said no thanks.

I crawl under the rig and the gear box thing is just zip tied to the frame.So I removed the one out of my wrecked truck(its speedo worked)swapped the gear box thing and the elc. sensor onto this truck and nothing!

I know the pcm is fried in this truck...I did the external volt. reg. per sticky instructions and now my alt is charging.Does the pcm control the speedo function also? is this why my known working parts arnt working in my new truck?

thanks,Mike.

rockmike

Nobody got nothing eh?

Is there a test i can do on the speed sensor,Like a voltage test while operating? some way of doing some diagnostics.

appreciate any help.Thanks

Onemoparnut

The computer definately controls the speedo that is why it is not working.

rockmike

Righton, I figured as much just, looking for some confermation.Im a black cloud newb trying to learn....thanks,apprecaite it.

Onemoparnut

Any time

wannadiesel

Actually the VSS is just grounded through the PCM, that's the only reason you need the PCM to have a working speedo. Ground the VSS directly and the speedo will work.

rockmike

Oh!! VSS? what is that and where is it located...thanks a bunch Wanna!! is that the doohicky im calling the speed sensor on the end of the gear driven box along side the trans? if so wich wire will I ground? thanks guys!!

rockmike

I gotta get more savy with my abreveations on these cummins trucks im lost lol

wannadiesel

VSS is the electrical thingy that hangs off the gearbox. Ground the black/blue wire for happiness.

rockmike

Thanks Wanna,This place kicks ****!! so much info and help when ya need it.

THANKS AGAIN!!!!!!!!!!!

RRRoger

I replaced my 1991 Getrag with a 1995 NV4500
Is there a way to wire the 3 wire sender to the 2 wire harness to get my Speedometer to work?
I also have an AfterMarket SunPro Speedo that will work with 2 or 3 wires but the colors do not match the SC105 VSS