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VSS wire for aftermarket navigation

7608 Views 8 Replies 4 Participants Last post by  Super Googan
2003 Ram 2500 Cummins 4wd. I need to locate the vehicle speed sensor (vss) wire to hook up an aftermarket radio with navigation. I have read that the vss wire is located on the PCM and is white/orange. I have found a white/orange wire going into the back of the instrument cluster. Is this the same wire and is it actually the vss wire?

I am not sure that the navigation will work any better with this wire connected, but the radio has speed adjusted volume that needs the vss to work properly.

CanBus does not have a harness for the 2003.
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not sure if these will help but from the looks of the one the white/orange IS speed control.

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Thanks for the reply. I studied the wiring diagrams from my service manual, but cannot determine if the white/orange wire at the back of the instrument cluster is the same as the one coming from the PCM. Can you tell? It would be a lot easier to make the connection behind the dash than running out to the firewall.
i would assume so, splice onto it and take it for a drive.
OK, I'll give it a try. This is an elusive question. I have been all over the internet and through my service manual trying to get a definite answer with no luck. I was following a lead to make the connection to a wire in the cruise control bundle and wound up blowing a fuse that took me a couple of hours to track down so I am a little cautious.
What sort of electrical signal is this wire supposed to generate? I'm curious for other reasons.
What sort of electrical signal is this wire supposed to generate? I'm curious for other reasons.
What I have read is that the Power Control Module converts the ac current from the vss sending unit(s) to a square dc pulse signal. I don't know much about electronics but apparently this is the signal that is interpreted by a microprocessor in the gauge cluster to give a reading of your traveling speed as shown on your speedometer. If someone has a more accurate explanation, please jump in.

I have found a purple wire in the harness coming from the steering wheel controls that emits a pulse, but it is not the right one for my nav unit.
The answer for my 2003 pickup with 5.9 liter Cummins diesel, 4wd vehicle speed sensor ( vss ) wire for connection to my aftermarket navigation stereo: Connect to the white/orange wire coming from the Powertrain Control Module (PCM) that is located in the engine compartment on the firewall on the passenger side. The PCM is the aluminum control box that has 3 small bundles of wires connected to the face. I actually made my connection on the driver's side where the bundle leaves the plastic loom that run high on the firewall. The wire bundle is exposed for a few inches before it enters a black rectangle connection box high on the firewall. Note: I attempted to make my connection behind the dash to save going through the firewall, but none of the wires that I tried including the white/orange wire behind the instrument cluster produced the correct vss pulse.
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