Speed Sensor Wire.. can anyone help

At least on the '03-'06 LSes, the PCM is on the firewall behind the glove box. The PCM is in the passenger compartment, but its harness is in the engine bay, so the wires you seek would be in the engine compartment.
 
SoonerLS said:
At least on the '03-'06 LSes, the PCM is on the firewall behind the glove box. The PCM is in the passenger compartment, but its harness is in the engine bay, so the wires you seek would be in the engine compartment.
Click to expand...

And what about '02 and under? Probably the same location? I'll have to take a look in the morning, anybody know for sure what it'll look like and how i'll know if i have the right wires?
 
I think it's in roughly the same place, but I've only seen an '00-'02 LS in person from the outside, so I don't know for sure.
 
from http://avic411.com Ive read the following

00-02 have a grey/black wire(make sure its not the speaker wire) behind the radio

03+ Speed Sense white/black driver kick, 20 pin plug, pin 9
 
02V8Sport said:
from http://avic411.com Ive read the following

00-02 have a grey/black wire(make sure its not the speaker wire) behind the radio

03+ Speed Sense white/black driver kick, 20 pin plug, pin 9
Click to expand...


I think that's the one that I tried hooking into, but it didn't work. I just gave up on it and rely on satilites only - but it's never gone down. Only annoying thing is the intermittent "Check Speed Pulse" on the screen.
 
So has anyone actually hooked up a navi system's VSS wire, to the white with red stripe wire, located at pin 13 on the PCM..on a 00-02 LS? If so, did the VSS function then work properly for you?
 
Hate to revive a 10+ year old thread. But I'm needing to figure out which wire is the speed sense wire for an install of a Kenwood DMX906S in my 2002 Lincoln LS. A poster above stated that it's the grey/black wire at the back of the head unit on my year of LS. Has anyone verified that? Thanks!
 
2001LS8Sport said:
Sure it does! How else does the car know how fast it's going? There are many items on the car that need VSS information.

On my 2003 Aviator, the radio had speed sensitive volume. The VSS signal is sent directly to the head unit and is in one of the connectors in the back of the radio. It is a gray wire with a black stripe. If I recall, the connector only had 2 or 3 wires in it...the rest were blank. It was a 6 disk radio. There has to be a VSS signal in the car...if you can't find a wire, it may be on the CAN Bus. If so, there are adapters out there. But I'm betting you have the wire to your radio on your year.

The VSS signal is also present to the windshield wipers if you have speed sensitive delay.
Click to expand...

No, it does not! The speed data is communicated on the data bus (along with a lot of other stuff) to all those modules that need it. There is no discrete pulsed wire doing it, unlike the older non-multiplexed/bused cars.
 
skizot722 said:
Hate to revive a 10+ year old thread. But I'm needing to figure out which wire is the speed sense wire for an install of a Kenwood DMX906S in my 2002 Lincoln LS. A poster above stated that it's the grey/black wire at the back of the head unit on my year of LS. Has anyone verified that? Thanks!
Click to expand...

Sorry, it doesn't work that way. The speed is communicated to the radio via the data bus connection, along with such data as if the driver's door is open or closed (radio uses this too) and a lot of data that the radio does not use.

On the Gen 2 cars, the ABS module does produce a pulsed VSS signal that goes to the nav module in the trunk. The 1st gen didn't have a nav option. I don't know if the 1st gen ABS module puts a signal out on that same pin. It may or may not. In any case, there won't be anything usable under the dash. You may have to settle for tapping one of the wheel speed sensors, or the transmission output shaft sensor. Better hope that your GPS does not load the signal too much, since those signals weren't meant to be used this way.
 
I guess that brings me to my next question. Is no one connecting the VSS input, somehow or another, to their 00-02 LS with aftermarket head unit? It's required by Wireless Apple CarPlay.
 
Just realized my factory Alpine head unit has a "Speed Volume" setting, which goes from 0 - 7. The manual states:

"
Speed sensitive volume: Radio volume changes automatically ands slightlywith vehicle speed to compensate for road and wind noise.
Recommended level is 1–3. Level 0 turns the feature off and level 7 is
the maximum setting.
Press MENU until SPEED VOL X appears in the display. Then press
SEL to increase ( ) or decrease ( ) the volume setting. The level
will appear in the display."

I'm assuming that the only way for that to work is that there is already a speed sense wire going into the back of this head unit. Would my assumption be correct?
 
skizot722 said:
...I'm assuming that the only way for that to work is that there is already a speed sense wire going into the back of this head unit. Would my assumption be correct?
Click to expand...

Well, it's been explained a few times in this thread, but I guess the explanations are missing the mark.
The LS uses a data bus, just like a network for computers. This "network" has many different bits of data on it, and one of those is the car's speed. If you plug in a good OBD2 reader, you can see the speed, engine RPM, temperature, and a whole lot of other stuff. All those things come from the data bus, a pair of wires with digital data on them. So, two wires take the place of the dozens of wires you would need if each wire only communicated one thing, like speed.
There's no speed sense wire going to the radio, instead there is the data bus. The factory radio knows how to pull the information it needs from this bus, but the aftermarkets don't.
 
Joe, I can sense your irritation. I don't have the pinout in front of me to know whether it's coming from the data bus, or a dedicated wire. I'm a software engineer for a living, so I'm well versed in "digital data".

It's surprising to me that the aftermarkets don't have a way of reading this data. the OBD-II signal protocols are not proprietary (Ford's is SAE J1850 PWM, and this is an 02 so it's not going to be CAN). That's exactly how you can hook a reader in and pull these data streams. I know there is the iDatalink Maestro product, but I think it uses CAN for most of its data retrieval.

Anyways, thanks for the response
 
Sorry, it's just that that question was answered about three times in this thread already.
There is a thread on here somewhere by a guy that put THX navigation from a 2nd gen into a 1st gen. It should indicate where and how he got the VSS signal for it.
 
Thanks, Joe. I searched, but can't find the thread you are referring to. Do you recall which one?
 
Thinking that the OSS (Output Speed Sensor) from the transmission will be the best place to tap into for the speed sense. Problem is, I have no idea how I would be able to get at those wires at the sensor without lowering the transmission. Does anyone happen to know where that bundle of wires comes up from the transmission, and which two wires (believe it's a two-wire speed sensor) are coming from the OSS?
 
I can look up the wire colors tonight. Ultimately, those wires run to the PCM. The PCM is under the dash behind the glove box, but all the wiring to it is on the engine side of the firewall.
 
The wire you would need to tap into for the transmission output shaft speed sensor is white with red stripe, pin 26 of PCM connector C1758. It looks like at the PCM and at the sensor itself are the only two places it is at. It does say that the output shaft sensor is on the left side of the transmission.

Note that there is also a white wire with red stripe at pin 23 of the PCM. This one is the transmission temperature sensor.
 
joegr said:
The wire you would need to tap into for the transmission output shaft speed sensor is white with red stripe, pin 26 of PCM connector C1758. It looks like at the PCM and at the sensor itself are the only two places it is at. It does say that the output shaft sensor is on the left side of the transmission.

Note that there is also a white wire with red stripe at pin 23 of the PCM. This one is the transmission temperature sensor.
Click to expand...

Thanks! That'll save me some time. Can you confirm whether this wire is AC or DC? I'm sure a dumb question, but I swear I read a post somewhere that stated it was AC.
 
skizot722 said:
Thanks! That'll save me some time. Can you confirm whether this wire is AC or DC? I'm sure a dumb question, but I swear I read a post somewhere that stated it was AC.
Click to expand...

Well, it's really a matter of perspective, but strictly speaking it's AC. (if the diagram is accurate) Your headunit may be okay with that.
 
Half-tempted to get this:



AutoChimp GPS to VSS Converter VSS Wire Simulator Aftermarket Stereo

It's $99, but debating whether it's worth it vs. potentially damaging the PCM or head unit somehow. The cost of replacing either latter component is much higher.

EDIT: Whelp, doesn't look like they ship to the US anyways. It's an Australian company that makes the adapter.
 
Last edited:
So, to me the main advantage of having the vehicle supplied speed info is that the navigation can continue to work reasonably well for a short while after there is no GPS signal. This happens in tunnels (some tunnels do have turns), thick forests, and very stormy weather (thick clouds).
 
You must log in or register to reply here.

Members online

No members online now.
Total: 137 (members: 0, guests: 137)
Back
Top