Thinking about a S10 digital dash swap. What do I need for Speedo and tach?

[BuickMike]

So I have a '89 S10 digital cluster that I'm thinking about swapping into the GN. It has been done before in an LS powered Regal so it will fit. I'm sure that I can plug the speedo into the VSS signal wire and it will work, however the sensor gets its reading from the speedo itself on the analog dash. Do I need to somehow leave that part in place? For the tach, do you think the tach on the new dash will work on the signal wire off the old one, or do I need to get a converter like Caspers has for aftermarket tachs? Keep in mind these clusters come from the 2.8 and 4.3 Chevy V6 powered Blazers. Thoughts?

Here is a pic:

 

[BuickMike]

Nobody?

 

[earlbrown]

I didn't realize they went back that far. My '94 Blazer had the same dash.

You'll need the oil pressure sender out of the donor car for sure. You might need the temp sender too if they use a different range.

For the fuel gauge to work correctly, you'll need to verify they use the same ohm range across the board as the GN sending unit. Volts are volts.

For the speedo to work correctly, the pulses per mile with have to match the GN VSS's. I want to say the GN is 2000 pulses per minute at 60MPH but don't quote me on that.

 

[pacecarta]

years ago i got as far as converting a dash bezel backer , installing the S10 gauge pack to it and pinning out the harness connector but never made it into a car, its up on the shelf ..way up high

 

[BuickMike]

Thanks Earl. You know what I can do? I can easily tap into the sensors. wire them up to the cluster, and see if they are accurate or not.

It will be easy enough to tap into the existing VSS, fuel, and tach signals to see if they line up or not before attempting to mount this cluster. I have Autometer water temp and oil pressure senders already in it. I'll just plug into those and see if it is close or not. Honestly I don't want to depend on the Blazer oil pressure and water temp gauges because they are really slow to respond to changes. I'll probably leave the Autometers hooked up in the center console just to be safe.

The VSS issue I am talking about is how to keep the sensor on the old cluster where the speedo cable plugs in? The Blazer cluster does not have a cable that goes into its cluster. Maybe I can take out that part and leave it connected to the cable in the back of the dash? How does the TR digital cluster work?

Also concerned about the tach signal. The TBI 2.8 and 4.3 blazers all had distributors with one coil and not a coil pack. I was under the impression that the signal in our cars is different and needs some kind of adapter.

 

[V6sleeper]

Subscribed..

 

[pacecarta]

when we did the cyberdyne dashes thats what we did
gut the speedometer , you dont need the needle section just the back end , leave the opticconnected put a cup over it and leave it under the dash

 

[vader87]

^^^^^^^^ Same Here

 

[earlbrown]

My Blazer with that dash responded plenty fast enough for me. I'd stick with GM sensors just to eliminate one headache.

If you verify the Blazer speedo will play nice with the Buick VSS, I'd get a junkyard cluster and gut the VSS out of it. Then just leave it behind the dash somewhere.

The other trick is to see if the Blazer dash is OK with out tach lead behind the alternator. I know some aftermarket tachs don't like it, but a fellow GM unit might be OK.

 

[BuickMike]

Oh, the wire with the green connector is a tach lead, huh? That'll be easy enough to check. Heck I'll plugin to the Autometer senders too since I can just test it out under the hood. If they don't work it is no biggie and I can grab GM sensors. Doesn't hurt to try since they are already there. I can tap into the VSS wire at the ECM and see if that works or not. I can tap into the fuel sender at the back of the car. That way I can see if this is going to work or not without even having to take apart the dash.

 

[V6sleeper]

Too bad the tach on the display didn't go higher, your into the color zone at 4500.

 

[BuickMike]

Yeah it only goes to 5500. That being said, there is a 6500 RPM tach version that comes on the Vortec 4.3 powered ones. Those are hard to find though.

 

[BuickMike]

Update. Tach and fuel sender signals work perfect! Just for the fun of it, I tried plugging an alligator clip onto the oil and water temp sensors and got bad readings. That being said, the readings were different depending on whether I had the ignition on or not, so I think the gauges were interfering. Just for giggles I'll remove the sensor wire from the Autometers inside the car and connect them directly to the cluster and see what happens. If it is still wrong no sweat. I know GM senders work fine. I'm almost over the hump with compatibility. Now I just need a convenient way to connect to the VSS signal and see if the speedo is accurate. If it is, I'm home free barring fitment.

 

[BuickMike]

Did some Googling and verified that resistances are different between Autometer and GM sending units. Oh well.

 

[BuickMike]

Looks like my stock GN water temp sender is the same part #. The oil pressure sender is a different part though.

 

[earlbrown]

GN' don't have an oil pressure sender. Just a 4psi switch.

Probing the VSS should be easy enough. There has to be a wire at the ECM for it.

Vortec 4.3 dashes should be easy to find. When I bought my Blazer it had a bad dash so I found a guy on ebay that sells remanned dashes with an upgraded power supply for a little over $50.

 

[BuickMike]

I'll dig through my spare parts box to see if I have my old water temp sender as I think it is compatible. I'll hit the local parts store for an oil pressure sender.

So according to my readings, all TBI up to '92 and '85-'89 TPI VSS are 2000 pulses per mile square wave, which is the same as the GN! So tapping the brown VSS wire should work perfect. It is not clear whether or not the Vortec motors used this sensor or a 4000 pulse per mile sine wave unit. My guess is that they kept it simple and used the older style sensor. Either way I will stick with what I have. The remanufactured dashes now are quite a bit more ($175 and up) and have a core required, so I would not be able to swap a 5500 RPM unit for a 6500 RPM one. Mine was broke too when I got it, but as with most of them it was just a bad power supply board. I got a new one for $40 and soldered it in myself. Maybe I'll hit the yards one more time and search for a 6500 one, but honestly it is not a huge deal to me.

 

[earlbrown]

Vortec 4.3's are not by any means rare. 90%+ S10s with 4.3s were Vortecs starting in the early 90s I believe.

Then again, if you can read a tach while above 4500, you're GN is too slow

 

[BuickMike]

The Vortec 4.3's were only produced in the 1st gen S10's for 2 years. They were not all that rare, but to find one with a digital dash is tough. I knew a bunch of people with Vortec S10 Blazers and not one of them had the digital dash. I really don't care about the tech that much. I put it in drive and let it shift itself. Really only a large full sweep analog tach would be readable at those high RPM's so it is not a big deal. The good thing is that once I get this one mounted, if the 5500 tach bothers me enough I'll go junkyarding here and there to see if I can find another one.

 

[BuickMike]

Well crap. Stuck a wire in pin A10 on the ECM and hooked it up to the VSS wire on the digital dash. Took it for a spin and the speed is exactly 1/2 of what it should be. Now what is interesting is that the GN is DC current 2000 pulse where the 4000 pulse VSS is supposed to be AC. Hmmmm, not sure what to do. I would have to run dual VSS to make this work.