Re: 67-72 Electric speedo
 

10x or 10mph?

Re: 67-72 Electric speedo
 

It's wierd because of the rate that it climbs but it is around 10 times what it should be. 0 to 100 in a second:lol:

Re: 67-72 Electric speedo
 

I haven't messed with GenIV stuff much, but if I remember correctly, they don't have a dedicated speedo output from the ECM, it was a CAN BUS signal to the instrument cluster. They do however have an 128k ABS output that I was thinking could be programmed to work with a speedometer. I am assuming this is what you have it hooked to? Do you have a local tuner that can look at it for you? It turned out nice, would be a shame not to be able to use it.

Re: 67-72 Electric speedo
 

Hey Eric, I think the CAN BUS is what I have it hooked up to now, but I am working with a local tuner on the solution. I also tried tapping into the hi ref side of the vss with no luck. We will look into the abs output in hp tuners if it can be dialed down to the 4000ppm for the s-10 speedo. Fingers crossed on this one. Thanks for the reply:metal:

Re: 67-72 Electric speedo
 

I am having a similar issue, I have 00' 4.8L with 20" wheels/50 tires, 3.08 gears, and NV3500 manual trans. My speedo is about 2x what it should be (reads 90 at 45). Does this need to be adjusted with a tune due to the tall trans/gear/wheel size?

Re: 67-72 Electric speedo
 

I'm thinking its due to a difference in speed sensors. It should be fixable in the tune though, you would have to talk to your tuner to be sure.

Re: 67-72 Electric speedo
 

I am having it tuned Thursday so hopefully that resolves the issue. If I have the wires on the VSS backward (the pigtail I bought just had 2 black wires), would this cause the speedo to read high or would it not read at all? The pigtail on the original harness had the purple vss wire on the right so I put the right black wire to the VSS lead to my speedo so I assume it is correct but thought I would ask, thanks.

Re: 67-72 Electric speedo
 

If those two wires are switched it wont make any difference.

Re: 67-72 Electric speedo
 

Any updates for this?

Re: 67-72 Electric speedo
 

It's been quite some time since I've posted on this page, but I've still found a lot of useful info including the write up on this Speedo conversion, so thanks for that. I'm hoping I can get some help wiring this thing. I've tried to follow the picture but it's a bit difficult with all the wires bundled together. Thanks again for the write up and any help is much appreciated. The bottom picture is what I have so far.

Re: 67-72 Electric speedo
 

It looks as though you have most of it figured out. You just need to tie the dash lights together and add ignition power, ground and a signal wire for the gas gauge. Is there something specifically you need to know?

Re: 67-72 Electric speedo
 

Do I tie in the turn signal lights with the rest of the dash lights? It looks like you grounded something above the fuel gauge? I was thinking it might be easier if I wire my plug into the truck harness first and then follow it over the the gauges? The ignition power needs to run to each gauge?

Re: 67-72 Electric speedo
 

You don't tie the turn signals with the dash lights because if you did, they would light up whenever the dash lights are on. They need to be hooked up to the wires that power the turn signals, they are dark and light blue. The ground above the gas gauge is just where I decided to ground the whole cluster, you need to be sure it has a good ground.

You can wire the truck side first if that makes it easier for you, it doesn't matter which you do first.

Yes, all the gauges that are electric will need their own ignition power.

Re: 67-72 Electric speedo
 

Duh... that makes sense. Thanks for the help

Re: 67-72 Electric speedo
 

So I think I have this figured out, but I'm unsure of where the red and green wire go?

Re: 67-72 Electric speedo
 

I missed this one! AAAAhahahahahahaha!
On a more serious note... I have not done my swap yet and am out a few months due to moving etc. I am very thankful you fellas are figuring this out though. I may have missed it in here but when this is done and working right - I can still have my stock tach as well?
Oh and you are very right! It's tricky! So you are right on time...:mm:

Re: 67-72 Electric speedo
 

Yes, you can still have the factory tach, you just have to trim one side of the face of it slightly to clear the speedo. It doesn't show when installed so you will never notice it. I will look and see if I can find a pic.

Re: 67-72 Electric speedo
 

You mean pink and green? There are pins that stick up on the back of the circuit board, and by them they are labeled what they go to. The pink goes to Ignition power and the green goes to Speedometer out put. If I remember correctly they are labeled IGN and SPD.

Re: 67-72 Electric speedo
 

Yes pink and green. I have them on the circuit board but I don't know what to hook them up to in the truck. I did want to ask, there was a wire labeled ammeter to ignition. Can I use that as my ignition power? Would i get speedometer output from the ecm? Or is that what vss is? Sorry for all the questions but i think i got in over my head on this one.

Re: 67-72 Electric speedo
 

I'm not sure what that wire labeled ammeter is, but I probably wouldn't use that for ignition power. The gauges will have power already going to them, so you would just need to use that wire. The speedometer wire would come from the PCM.

Re: 67-72 Electric speedo
 

I rewired the whole truck with a painless harness and the ammeter to ignition was one of the wires in the stock cluster plug. I cut that off and spliced in my connector for the updated gauges. So the green wire from the speedo I need to wire to whatever it is out of the pcm?

Re: 67-72 Electric speedo
 

The speedo out put from the PCM will be pin 50, a dark green with white stripe in the C2 connector, which is either the red or green one depending on what year your engine is.

Re: 67-72 Electric speedo
 

Thanks

Re: 67-72 Electric speedo
 

So I guess I don't have this down yet. I got the speedo hooked up to the ecm but I'm not sure of the ignition source. I have a wire from the truck labeled gauges B+, which leads me to believe that's hot all the time? I don't want power to the gauges all the time do I? The other wire I have is the one labeled ammeter to ign sw, which I'm guessing is ignition switch. Do I need 2 ignition sources? One for the speedo one for the other gauges?

Re: 67-72 Electric speedo
 

I just took a test light to those wires. Gauges b+ is hot key on, ammeter to ignition switch is constant hot and I have a wire labeled ammeter to fuse block which is constant hot. I'm lost...

Re: 67-72 Electric speedo
 

I studied your picture, I think I have this figured out. I see you have all the ignition wires coming off the fuel gauge and I'm thinking the wire i need is the gauges b+ since it's only hot keyed on.

Re: 67-72 Electric speedo
 

Yes, you only need one key on hot wire to go to all the gauges. Are you trying to hook up the factory ammeter?

Re: 67-72 Electric speedo
 

No I did the square body voltage gauge swap. Those are just the wires I have in the truck harness. I'm not sure why those ammeter wires are constant hot and the gauges b+ is not. I'm gonna use the gauges b+ wire and just leave the others alone. Thanks for all your help I think, i hope i have this figured out. Thanks again

Re: 67-72 Electric speedo
 

I plugged in my gauges the other day and as soon as I turned the key the the fuse blew. My dash lights and turn signals are working so I assume my grounds are good. I hooked up each gauge one by one and when I got to the volt gauge I swapped from the square body the fuse blew again. Do I have a bad gauge or is it something else? Thanks in advance for any help.

Re: 67-72 Electric speedo
 

Can you post a pic of how you have it wired? My guess is it isnt wired quite right.

Re: 67-72 Electric speedo
 

I will try to get a picture later today.

Re: 67-72 Electric speedo
 

Here it is

Re: 67-72 Electric speedo
 

Well, I cant really tell from the pic, but I would make sure the voltmeter isnt grounding out on the tin.

Re: 67-72 Electric speedo
 

I ran all my grounds to the screw just above where the factory plug plugs in. Then I grounded my plug just to the right of that. My lights are working so those should be fine right? Are you saying check that the gauge itself isn't grounding out in its mounting?

Re: 67-72 Electric speedo
 

Yes, make sure the mounting bolts are not touching the tin. There are little plastic parts that insulate them, make sure they are there.

Re: 67-72 Electric speedo
 

Great I'll check that out. Thanks so much

Re: 67-72 Electric speedo
 

So that was the issue, fixed that but none of the gauges work. Lights are still good, except ses light. I'm ready to throw in the towel....

Re: 67-72 Electric speedo
 

Did you fix the fuse that blew? If you have power to the gauges I would think that at least one would work, highly unlikely that they are all bad.

Re: 67-72 Electric speedo
 

Yes I did, it was grounding itself out. The only needle that moves is the gas gauge but it goes to empty when I turn the key on and the tank is not empty. The volt gauge doesn't register anything. I cant keep it running long enough to see if the temp gauge works. And I have no idea when I'll be able to test the speedo. My check engine light doesn't come on when the key is on too.

Re: 67-72 Electric speedo
 

ls1nova71 pm sent!