Vehicle Speed Signal Input for Head Unit
06-27-2018, 12:09 AM
#1
Instructor
Thread Starter
Vehicle Speed Signal Input for Head Unit
Hey Everyone,
I am trying to connect my new Pioneer head unit and could not find the vehicle speed signal (VSS) wire. Has anyone installed a head unit with GPS and found this wire behind the PCM? This would help a lot, thanks!
I am trying to connect my new Pioneer head unit and could not find the vehicle speed signal (VSS) wire. Has anyone installed a head unit with GPS and found this wire behind the PCM? This would help a lot, thanks!
06-27-2018, 01:03 AM
#2
Burning Brakes
If you have the BOSE amplifier, then you will need NAV-TV's MOST-HUR box to get the VSS wire. Other cheaper MOST boxes do not give you VSS.
That said.. I think that the VSS is not mandatory. It only helps with accuracy. The GPS receiver that came with your head unit is more important.
If your car already had the PCM's GPS, then maybe there's an adapter that enables connection to the head unit directly.
Knowledgable users please correct me if I'm wrong.
I did a head unit replacement for my 997.1 with BOSE recently and used a cheap MOST box.
What's more important is the parking brake and reverse wires in case your new head unit has AndroidAuto/CarPlay support, reverse camera etc.
You can either connect those wires faithfully or bypass the parking brake - which is whatI'm planning to do since AndroidAuto is very buggy and annoying.
That said.. I think that the VSS is not mandatory. It only helps with accuracy. The GPS receiver that came with your head unit is more important.
If your car already had the PCM's GPS, then maybe there's an adapter that enables connection to the head unit directly.
Knowledgable users please correct me if I'm wrong.
I did a head unit replacement for my 997.1 with BOSE recently and used a cheap MOST box.
What's more important is the parking brake and reverse wires in case your new head unit has AndroidAuto/CarPlay support, reverse camera etc.
You can either connect those wires faithfully or bypass the parking brake - which is whatI'm planning to do since AndroidAuto is very buggy and annoying.
06-27-2018, 01:44 AM
#3
Instructor
Thread Starter
Sorry, forgot that piece of information. I have a 997.1 non bose, PCM 2.1. Thanks for the input! I saw that it does not do that much of a difference but figured it is worth a shot to try! Also, is there a pin for the illumination? I am following this link: https://cai-store.com/pages/997-boxs...o-installation. The guide says to tap into a wire in another harness. However, I noticed that the PCM lights up when I turn on the headlights. This must be triggered by an illumination pin into the PCM, correct? Although after looking at the wiring diagram I am not sure how...
I noticed that the PCM also has SDV, which I assume is speed dependent volume. How would it have that without a speed sensor input in the back?
I noticed that the PCM also has SDV, which I assume is speed dependent volume. How would it have that without a speed sensor input in the back?
06-27-2018, 02:32 AM
#4
Burning Brakes
Actually.. the VSS signal comes from the Can-Hi and Can-Lo wires (data protocol). So there isn't a direct wire corresponding to this.
I suddenly recall now that the NavTv box also takes in these 2 wires - so it makes sense that VSS comes out of it.
I also vaguely remember that the brake signal and the reverse signal come from the CAN wires.
For illumination I just tapped into a switched power wire (Acc that goes into the head unit). I don't know if dimming the lights is that important to you.
I have a multifunction wheel in my car and almost all the modules that claim to work with the 997 say that they support VSS (and a couple of other signals as well).
But so far, the only module that I can confirm works with the 997 is the one from Connects2. Everybody else misleads you into thinking it all works - when they don't!
I'm waiting on my modules from Connects2 to arrive from the UK - will report my progress then
I suddenly recall now that the NavTv box also takes in these 2 wires - so it makes sense that VSS comes out of it.
I also vaguely remember that the brake signal and the reverse signal come from the CAN wires.
For illumination I just tapped into a switched power wire (Acc that goes into the head unit). I don't know if dimming the lights is that important to you.
I have a multifunction wheel in my car and almost all the modules that claim to work with the 997 say that they support VSS (and a couple of other signals as well).
But so far, the only module that I can confirm works with the 997 is the one from Connects2. Everybody else misleads you into thinking it all works - when they don't!
I'm waiting on my modules from Connects2 to arrive from the UK - will report my progress then
06-27-2018, 12:53 PM
#5
Instructor
Thread Starter
Woah that makes a lot of sense! So now it looks like I have 2 options:
1. Splice into the wires behnind the head unit for ignition, illumination, and run reverse trigger to the tail light.
2. Buy a generic can bus adapter that supposedly gives me those wires. The connects2 does not ship to the US on ebay
Maybe this one? https://rover.ebay.com/rover/0/0/0?m...2F290641217076
1. Splice into the wires behnind the head unit for ignition, illumination, and run reverse trigger to the tail light.
2. Buy a generic can bus adapter that supposedly gives me those wires. The connects2 does not ship to the US on ebay
Maybe this one? https://rover.ebay.com/rover/0/0/0?m...2F290641217076
06-27-2018, 01:53 PM
#6
Burning Brakes
The wires in the PCM's incoming harness do not supply switched power directly.. they only had constant power.
So I had to use a fuse-tap to add an additional circuit from the fuse box itself - I think it was fuse B9 (telephone) that had switched power based on ignition.
Yes.. again.. if you have no use for the reverse signal.. then I would skip it.
Running a wire to the rear lights is itself a significant effort.
For these accessory CanBus signals, you could try the Paser module - I've confirmed from their Tech Support that it does work for the 997.
Their Unican Plus box supports some steering controls on 997 as well (just volume and seek.. nothing else) - that's why I chose Connects2.
Unican has a bunch of specialized versions - there is a Pioneer specific one that's slightly cheaper than the generic box.
Unico Dual should also work fine - just browse their site and put in the car model - it should list the relevant modules.
It should ship directly from them or you can find on eBay as well.
https://automotive.paser.it/en-gb/Co...58c62c341.html
I ordered my Connects2 via eBay only. But I had to order the full kit as opposed to just a Can-Bus box.
You could use this video for reference on the harness:
So I had to use a fuse-tap to add an additional circuit from the fuse box itself - I think it was fuse B9 (telephone) that had switched power based on ignition.
Yes.. again.. if you have no use for the reverse signal.. then I would skip it.
Running a wire to the rear lights is itself a significant effort.
For these accessory CanBus signals, you could try the Paser module - I've confirmed from their Tech Support that it does work for the 997.
Their Unican Plus box supports some steering controls on 997 as well (just volume and seek.. nothing else) - that's why I chose Connects2.
Unican has a bunch of specialized versions - there is a Pioneer specific one that's slightly cheaper than the generic box.
Unico Dual should also work fine - just browse their site and put in the car model - it should list the relevant modules.
It should ship directly from them or you can find on eBay as well.
https://automotive.paser.it/en-gb/Co...58c62c341.html
I ordered my Connects2 via eBay only. But I had to order the full kit as opposed to just a Can-Bus box.
You could use this video for reference on the harness:
06-27-2018, 02:14 PM
#7
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Years ago I installed a Pioneer navigation unit in the 997.1 non-Bose I had at the time. I did not connect the VSS or parking brake wires, and instead just grounded them. Doing so saved me some installation headaches as well as enabled destination input while the vehicle was in motion. The unit was still very accurate with respect to GPS location. The system used the VSS signal to check itself, not for location data.
