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TBI swap wiring question

NEK5

NEK5

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Did some research, but couldn`t find what I was looking for. I`m putting an 82 cab on my 90 Blazer frame. I`m using the 82 motor, and putting my TBI from the 90 motor onto it.

Now, I bought a stock EFI harness from an 89 burb from 3car here on CK5. What else do I need to make this work? Do I have to use my 90 harness still, or can I just buy a universal harness to use? I`d like to use my 90`s cluster as well, unless if there`s a way I can swap to aftermarket gauges. (I`m not familiar with electronic speedos, or VSS) Would it be possible to use after market gauges?

TIA
 
You are probably going to want to stick with the '90 stuff, it's just going to make your life easier. Anything wrong with that harness that prohibits you from reusing it?
 
Well, its pretty much all spaghetti. A real mess. Are the EFI/ECM parts of the harnesses the same? I just bought one from an 89 Burb. Is that no good to me?

EDIT:

What if I use an 89 241 T case, and a 87-89 Cluster?
 
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If you swap cases and the cluster, yes it should be pretty pain free.

I personally think the electronic speedometer setup is superior, but if the harness is in terrible shape, may not be worth fixing. Not real difficult to decipher these harnesses though, probably just a matter of removing a bunch of taps and splices, then soldering and shrink wrapping those spots.
 
dyeager535 said:
If you swap cases and the cluster, yes it should be pretty pain free.

I personally think the electronic speedometer setup is superior, but if the harness is in terrible shape, may not be worth fixing. Not real difficult to decipher these harnesses though, probably just a matter of removing a bunch of taps and splices, then soldering and shrink wrapping those spots.
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The harness is pretty bad. The truck was in an accident/fire before I got it. So, when they fixed it, they really butchered it. It was almost impossible to put in an automatic starter/alarm in the thing.

I already have a 208 I can use. Will the 82 cluster work, or will I need an 87-89 one, for the VSS?

It actually makes it better for me to use a different setup (tcase/harness/cluster), as it will allow me to set it up in the cab before I even start swapping it, saving me alot of time when I do swap it. It will also give me time to replace any seals on the 208, and put the new speedo gear in.
 
'82 cluster might work, just look on the back of the speedometer for a rectangular cutout with a very small threaded screw hole next to it. This is where the VSS "eye" bolts up. If it's not there, all you really need is a speedometer that is a bit newer, anything '83-up with cruise for sure has the right setup.

At some point all speedometers would be setup for it, '87-89 TBI trucks are guaranteed to be setup correctly as well since all TBI used VSS, and '87-89 were still cable drive.
 
Awesome. Thanks Dorean!:wink1: You seem to be the only one who answers to these type of threads:crazy: I`m glad it`s you and not howdy doody:eek1:
 
Got another on for ya Dorian.

So, other than the t case, cluster, and the 89 EFI harness. What else will I need? As far as the rest of the wiring harness is concerned? Can I just use a universal harness for the rest of it?

TIA
 
Well, if you have the complete '89 harness, which would include the fuse panel, that's what I'd use. If you don't have the whole TBI fuse panel, you are going to need to add an auxillary fuse panel so you can fuse each EFI specific circuit as it should be.

You CAN add the DRAC (electronic speedometer) stuff to any setup very easily, the transfer case is the major sticking point for most people, but since you already have that, the rest is cake. If you don't go with the DRAC setup, you'll need a speedometer cable, and if you want an accurate speedometer, you'll have to play around with the speedometer gears. No such issues with the electronic setup. :)
 
dyeager535 said:
Well, if you have the complete '89 harness, which would include the fuse panel, that's what I'd use. If you don't have the whole TBI fuse panel, you are going to need to add an auxillary fuse panel so you can fuse each EFI specific circuit as it should be.

You CAN add the DRAC (electronic speedometer) stuff to any setup very easily, the transfer case is the major sticking point for most people, but since you already have that, the rest is cake. If you don't go with the DRAC setup, you'll need a speedometer cable, and if you want an accurate speedometer, you'll have to play around with the speedometer gears. No such issues with the electronic setup. :)
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As for the speedo gears, how would I go about getting those? I`m assuming they are sold for certain gear/tire setups, correct? I`ll be running 33"ers and 4.10s. I can add the DRAC, even with an 89 harness? What would I use, my 90s t case, and an aftermarket elec. speedo?

Thanks Dorian.
 
There are two speedo gears, drive and driven. Both have tooth counts, you figure out (theoretically) what is correct with your drivetrain info. Some places (TCI's website I believe is one) have speedometer gear calculators.

You can certainly add the DRAC, ignition 12V, ground, and the two wires from the VSS are all that are needed, then whatever output you may need. (speedometer, ECM, and cruise are the typical) DRAC replaces the earlier VSS buffer, so the wires will already be there, just need to splice them into a DRAC connector. DRACs were used on just about all "trucks", Astro's are the easiest and most commonly found. To the drivers side, upper part of the center of the dash.

You'll need to pin the instrument cluster connector a bit differently, swapping the wiring around to feed the speedometer correctly. Compared to swapping the harness itself, that is childs play.

You could probably use an aftermarket speedometer, but a stock '90-91 cluster would be easier and probably cheaper, local 'yard wants $30 for a complete cluster for instance.

Wiring typically seems daunting at first, but once you start digging into it, it makes a lot of sense and is very easy to deal with. Short of the troubleshooting aspect, electrical is a whole lot easier to deal with than the mechanical side, you only need to use your brain. :) You really do need to dig into it though before it all actually starts to make sense, at first it just looks like a ball of spaghetti. Believe me, I sat in my yard with my TPI harness and GM manual for a couple of days trying to figure some of it out before it started to coalesce in my head.
 
Sounds good. So with that calculator, I can tell what speedo gears I will need?

Thanks Dorian!
 
Yes you should be able to, but take into mind that advertised tire diameter and actual aren't always the same. Will probably be close enough, I think my tires are within .3" to advertised, and the calculations I used for 33" tires put me within about .5MPH of actual at 60MPH. If you go with a mechanical speedometer, you can always put what you've got together, see if you get extremely lucky and it's dead on first (check with a GPS).

I went with cable drive first, then switched to the DRAC setup, it's just easier to deal with. Wish I had just gone that route in the first place, but again, I wasn't really comfortable with the electrical stuff at that point, and that prevented me from just doing it right off the bat like I should have.
 
Well, I plugged my numbers into a calculator, and it`s almost a dead on match. With 30"ers and 3.73s and a 700r4 (stock setup), its only about .5 MPH with 33"ers and 4.10s and a 700r4. So I may get lucky and be alright. I`m still wondering about the VSS. I checked my 82 cluster, but still not sure what I`m looking for. Will an aftermarket mechanical speedo have the input for VSS, or is that something that needs to be added with a module?

I did some more searching, and found a post of yours about VSS from october. So, I`m reading the article you linked to on jagsthatrun.com right now:wink1:
 
So I`ll need a two pulse vss, in order to use my 89 harness, 208 t case, and mech. speedo? What if I don`t use a stock cluster?
 
Jagsthatrun is actually the place that sells a bunch of different VSS signal generators, however they are a bit incorrect on some of the truck info. That's ok, because CK5 knows the story on the truck setups. :)

If you've got the '82 speedometer close by, just flip the cluster/speedometer over, and look at the back of it. You see the small round piece that the end of the speedometer cable goes in, that rotates to show speed? If you hold the speedometer as it would be installed in the vehicle, on the PASSENGER side, rear of the speedometer, very near the piece the speedometer cable drives, there should be a small rectangular cutout, with a screw hole centered and just off to the side. That's where the VSS "eye" bolts in. If it's not got the cutout, you'd need a different speedometer.

As cheap as these clusters are, you could get another stock speedometer for very little $$, which would save you having to buy a VSS signal generator, which is going to be no better than the stock pieces.

Edit: per your above post, yes the ECM and cruise needs the 2 pulse VSS. See above info about aftermarket VSS generator. Too much money IMO.
 
Alright, from what i see there is a cutout, that, if I spin that piece the cable mounts too, I can see a blade spinning. Next to the cutout, there is 3 holes. 1 level with the top of the opening, one level with the bottom, and one in the middle that is offcentered. Let me get a pic. so it makes more sense:o

EDIT: I also ditched the cruise when I did the TBI spacer. So that`s not a problem, as far as needing the VSS for the cruise.
 
Here`s the best pic I could get:

190327602821_0_0.jpg
 
Yep, setup for VSS, if the bigger hole is threaded. Just need the buffer, should be cheap from someone on here if you can't get it locally. All bolt up the same for cars 1981-90 (carbed) and all trucks equipped with cable drive VSS, but the connector on the other end is a variable. Not much in the way of differences, I *believe* the portion you care about (ECM feed) uses the same connector regardless of application.
 
dyeager535 said:
Yep, setup for VSS, if the bigger hole is threaded. Just need the buffer, should be cheap from someone on here if you can't get it locally. All bolt up the same for cars 1981-90 (carbed) and all trucks equipped with cable drive VSS, but the connector on the other end is a variable. Not much in the way of differences, I *believe* the portion you care about (ECM feed) uses the same connector regardless of application.
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From what I can see, the hole is not threaded?:confused:
 
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