Electrical Dakota Digital Gauges and VSS in a mass air converted car

Waz900

Member
Apr 22, 2005
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Sewell, New Jersey
Hey guys. I installed my Dakota Digital dash cluster, but I want to make sure my thinking is correct on this. My car is an '88 5-speed GT that had factory cruise control (so it has VSS) but it was factory speed density (no VSS pigtail to transmission). When I got the car, it was converted to mass air, but I don't believe they ran the VSS pigtail to the transmission. I tapped into the VSS signal on the drivers side kickpanel and ran that to the speed send terminal on the gauge control box per the instructions. Since I have done this, do I need to even run the pigtail to the transmission? The gauges will pick up the signal from the VSS wire, but if there is no pigtail coming from the transmission, will the car not know what the signal is supposed to be? Am I overthinking this? Do I need to still run the pigtail to the speed sensor in the transmission? Thanks in advance for your help.
 
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Mustang5L5

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Mod Dude
Feb 18, 2001
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If you've tapped into the wiring in the kickpanel, it's no different than tapping into it at the transmission. You are all set assuming the connection is good.
 

Waz900

Member
Apr 22, 2005
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Sewell, New Jersey
Awesome, thank you for the feedback. So the speedometer cable goes bye bye, and the DD supplied plug goes into the speed sensor. If there is no signal from the speed sensor plugged into the transmission, where does the vehicle get the speed signal from? Otherwise, how does it know how fast it is moving without knowing what is going on with the transmission?
 

Mustang5L5

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Mod Dude
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Well, you need the speed sensor to supply the signal. You can remove the speedo cable and install a later SN95 vss which is designed for use without a speedo cable.

why does DD have you remove and plug the VSS if the guages still need a signal?
 

Waz900

Member
Apr 22, 2005
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Sewell, New Jersey
So then I do need to wire in the pigtail? Otherwise the car doesn't know how fast its moving if it doesn't have the cable, right?. From what i've read about a mass air conversion, wiring up the VSS to the trans is optional-ish, meaning that you should do it but don't really have to. I've read that it can cause some stalling issues, but not all the time. So while this was optional at the time for the mass air conversion, when I remove the speedo cable, it makes it mandatory, or the car won't know the speed. I'm planning on getting the GPS module for the gauges, but i've been waiting on an LMR code to present itself in April. I'll have to look at the wiring for that to see if that might solve my problem instead of adding the pigtail.
 

JKWilson61

Active Member
Jul 27, 2018
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Summerville, SC
If you have a VSS on the transmission the DD controller receives it's signal from there. Where you tap the wire (at the computer, in the kick panel or at the VSS) doesn't matter. Electrically it's all the same connection. The plug DD supplies is to seal the hole left in the VSS when you remove (and discard) the speedo cable. The VSS is still left installed in the tranny and the speedo gear drives the VSS. With the DD speedo calibration process you don't need to worry which speedo gear you have installed either.

In a nutshell, remove the speedo cable from the car, leave VSS installed, install DD supplied plug into the VSS in place of speedo cable, make appropriate wire connections, follow DD calibration process, enjoy!
 

Mustang5L5

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Mod Dude
Feb 18, 2001
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If you plan on keeping the cruise control functional, you still need the VSS in the transmission.

I disagree about wiring in the VSS during a mass air swap being optional. I realize a few vendors sell the MAF wiring conversions without the wiring and don't even mention it in their instructions (LMR) but I think this is an error on their part and it should be mandatory, not optional. But that's a whole different thread.

But, long story short, if you plan on using the VSS for now to send a speed signal to the gauges, you will need to leave the VSS, plug the hole the speedo cable was plugged into, and tap into the wiring anywhere were you can pick up. A signal is a signal.
 

Waz900

Member
Apr 22, 2005
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Sewell, New Jersey
@JKWilson61 I have a VSS on the trans, but I do not have an electrical connection to it. I only had the mechanical connection via the speedometer cable. I think I need to wire a + and - wire from a VSS pigtail and run it to pins #3 and #6 on the computer. That is what should have been done when the car was converted to mass air. What adds another minor level of complexity (at least for my brain) is that I have a microsquirt installed now and not the normal EEC. I don't think that makes a difference, but i'd like to be sure.

@Mustang5L5 Completely agree. I figured all of this out after I went under the car to plug in the VSS pigtail, only to find that it isn't there. I also agree that wiring the VSS should not be optional, but people got by without doing it, and here we are. Had I done this conversion, I would have wired it up. I think I need to wire the VSS like i mentioned above and i'll be good to go.
 

Mustang5L5

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Feb 18, 2001
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@JKWilson61 I have a VSS on the trans, but I do not have an electrical connection to it. I only had the mechanical connection via the speedometer cable. I think I need to wire a + and - wire from a VSS pigtail and run it to pins #3 and #6 on the computer. That is what should have been done when the car was converted to mass air. What adds another minor level of complexity (at least for my brain) is that I have a microsquirt installed now and not the normal EEC. I don't think that makes a difference, but i'd like to be sure.

@Mustang5L5 Completely agree. I figured all of this out after I went under the car to plug in the VSS pigtail, only to find that it isn't there. I also agree that wiring the VSS should not be optional, but people got by without doing it, and here we are. Had I done this conversion, I would have wired it up. I think I need to wire the VSS like i mentioned above and i'll be good to go.


The wire for the VSS should be there. I converted my '88 to mass air. It did not have factory cruise control so there wasn't a VSS at all. I added the VSS and found the factory VSS pigtail connected to the crossmember by a clip. I plugged it in, and tapped into the wiring in the kick panel to connect to the ECU.

Given that your '88 has factory cruise control, it should be there. The VSS was still used for the cruise control in 86-88 speed density cars. Only the 86-88 non-cruise control cars did not get a VSS at all as it wasn't needed, but like I said my non-cruise '88 did have the original wiring clipped to the side.
 

Mustang5L5

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On the driver's side of the X-member there is a hole. This hole is where the VSS harness is clipped on cars that do not use the VSS (pre-mass air non-cruise cars).

Of course, it's been almost 40 years so who knows if its still clipped there.

1617900685665.png
 

Waz900

Member
Apr 22, 2005
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Sewell, New Jersey
I can telll you with 100% certainty that it is still not in that location. I had the entire engine bay replaced on my car and I’ve been putting everything back together. Even before me, the car was majorly modified (poorly in a lot of places.) I’m hoping the wires were just tucked away and I didn’t see them.

Here are a few pics just because.
 

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Waz900

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Apr 22, 2005
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I figured it out. They were there (sort of). I found this picture of the harness on eBay. I knew for certain that I didn’t have 3 connectors coming out of the grommet. When you get in real close, you can see the little nubs that someone cut the vss wires down to. They are green and orange. I bought a new pigtail and I am going to try to pull them through a little bit to splice them on.

Gotta love these cars.
 

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JKWilson61

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Sorry for going silent for so long. I've been sick most of the week and haven't done anything, including getting online. I read your posts and saw you're on a good track for getting your cluster wired. When I started reading and first saw your idea you did have the trans harness I was going to point you but saw you got it all figured out.

One note, it should go without mentioning that there are only 2 wires to the VSS. One wire goes to ground and the other to the harness for VSS signal output. Make sure you're tapping into the output leg and not the ground leg. I'd be happy to provide the wiring colors from the factory harness but I only have the '91 and '92 Ford manuals and wouldn't want to lead you astray. Mike (Mustang5L5) may be able to supply you with that.

I noticed you were concerned because you weren't running the EEC but instead had a microsquirt. Have no fear as it' doesn't matter. When the trans harness comes into the car it gets connected behind the left kickpanel. The VSS signal output is divided out at this interior connector. One run goes to the Cruise Control Amplifier and the other goes over to the EEC plug. Neither component is required to be hooked up. You're just using the VSS output signal. There is no power running from either component to the VSS is simply provides a reference input signal to those components. You can almost think of the VSS as a signal generator. The signal is not a power input or output but a reference to ground. It wouldn't be though of as voltage but frequency. Without over complicating it any further than I just did, as long as the VSS is installed in the trans and the factory plug is connected to it, you can simply tap your DD controller wire into the factory harness for the needed signal. It's a digital system so you can't necessarily apply "voltage thinking" to it.

Based on earlier comments I imagine you already have much of your wiring done so this may be a little too late. I was an aircraft electrician for over 15 years and am TOTALLY OCD when it comes to wiring and wiring mods. "Pretty" wiring jobs not only look nice, they are more dependable and easier to work on. With that said I really, really wanted to use the same colored wires for wiring to my controller as the factory wires they were being tapped off of. Most folks are happy just going down to the auto parts store and picking up the biggest assortment of colors they can find and they're (I think a large number also don't care and at all and will just wire everything with the same colored wire). Labels are an option but as I said, I'm OCD! After some searching online I found a company that sells automotive grade wiring in different gauges and multiple colors WITH multiple color tracers on them. They sell in single spools of different lengths or "kits with multiple color option in multiple length choices and color choices (e.g. 10ft lengths with 4 color choices). I was able to match up all of the applicable wire/tracer colors that are used in the factory harness and ordered their 10 color kit in 10ft lengths. They specify in the listing what color combinations come in the kits. As soon as you place your order though all you do is immediately shoot them an email with YOUR color choices and that's what they put in the kit instead. it cost me $27.95 (free shipping) and they were really fast and I got exactly what I asked for. The company is : 4rcustomswire. The single thing is that their tracers are marked spiraling down the length of the wires instead of straight (like factory wire). They state they prefer this way in order to more easily locate the tracer on the wire...and that is a valid point.

I know the DD cluster isn't cheap but man! I was blown away by the quality and craftsmanship...in addition to being 100% USA made. If you REALLY want to see how much you really got for your money, go to their factory tour on video Youtube. I bought mine from LMR and couldn't wait to tear that box open when it arrived. Keep us up to date on your progress with the install. Seems not too many people here have pulled the trigger on one. I'm happy I did!!
 

LX Dave

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Another Dakota Digital user here. Absolutely love mine. The factory cluster was so dark at night, I had to try to count the dashes on the speedometer to find out how fast I was going. I even pulled the red filters out and installed red LEDs. Went with the silver face, red lighting one. It did take a while to install (I hid everything really good) and it even pulls info from the Sniper fuel injection system for some of the gauges. This past Saturday was the first drive of the year, so calibrated the speedometer right away. Dead on from a crawl to over 100 accordingly to gps. For the VSS, I just pulled one out of something newer that didn't have a speedometer cable. Truck I think. Doesn't matter, they work the same.
 
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