Wiring a nearly 40-year-old race car with modern Haltech electronics

Installing a full suite of Haltech electronics–ECU, dash, power distribution module and even a fresh wiring harness–sounds like a clean, efficient, modern solution for a race car. Something a professional team with matching shirts and a Snap-on account would do.

So, naturally, I did it with one of my friends in his workshop, with oil-stained hands, questionable crimping technique, and …

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Sure, it took hours of planning, labeling, and rechecking circuits. Sure, Kevin’s fingers are still cramping from crimping 100 pins. 

It would have taken all that time and effort to do it the old way.  In a modern, dedicated race car once you get past the price it seems like the way to go.

Could we get an update from you about a year from now to see how it all worked out?

I feel like I'll be here in a couple of years. 25 year old electronics are terrible. Slow polling rates and really limited features. It just seems like a daunting prospect to strip everything out, but removing fistfulls of unused wiring would feel great.

Questions about wiring (this is very timely)!  Here goes from things I'm curious about in this article;

1. What are you using for harness labeling?  I think I see clear heatshrink over the yellow labels.  How are you creating the yellow labels, what materials and tools?

2. Are you labeling individual wires?  I went looking for a heat shrink label printer last night for a project and I don't know how to make heat shrink labels for 20ga and smaller diameter wires.  I know there are labels that can be zip tied to wires but uuugh that's not sexy.

3. Are you reusing wire colors from how Mazda built the car originally or is there some other way of deciding what wire colors you used?  Perhaps Haltech has guidance and you're following that? 

4.  What do your wiring diagrams look like, how were they created, etc?

theruleslawyer said:

25 year old electronics are terrible. Slow polling rates and really limited features. It just seems like a daunting prospect to strip everything out, but removing fistfulls of unused wiring would feel great.

Yet 40-50 year old electronics are wonderful. The ignition module has been on the Datsun since 1985.

25 years ago folks reactions to my carbureted motor were usually swap to EFI because cabureted cars need constant tuning. Meanwhile they were constantly fiddling with their laptop.

Of course modern EFI is better in every way and it sounds like this new system is truly awesome.

In reply to Noddaz :

I did it the old way and can confirm it took alot less time then doing it the proper way. 

I'll let you know how it all goes in a year!

In reply to theruleslawyer :

It does FEEL really good removing old wiring. Its like the fun demo part of a home project, the rest of the stuff is a wee bit less fun. 

In reply to Tom1200 :

The thing about EFI is the ability to refine way beyond what carbs and points are capable of doing.  That's why people are always on their laptop.  

Add to that, you can see which part is causing hesitations or surges vs trying to figure out which fuel circuit in the carb is supposed to be covering something.

In reply to pres589 (djronnebaum) :
 

1. Yes, you’re absolutely right—you’re seeing clear heat shrink tubing over yellow printed labels. This method keeps things clean, durable, and professional-looking.

• We used vinyl, printed using a label printer Brady BMP21.

• Protection: The label is applied directly to the wire or bundle, and then clear heat shrink is placed over it and shrunk down. This protects the label from abrasion, chemicals, and heat—critical for anything going into a hot engine bay or under the dash.

2. Yes, individual wires are labeled—especially when you're dealing with a custom harness, it's basically essential.

• For 20 gauge and smaller wires, we use heat shrink tubing with pre-printed text. You can:

  • Use a printer that supports heat shrink material, like the Brady BMP21

  • Load the printer with heat shrink tubing cartridges, not just regular label tape.

  • These printers let you size your font and shrink tubing to match wire gauges. For 20-22 AWG, you’ll want 1/8" diameter shrink tubing or smaller.

• If you're not printing directly to heat shrink, you can:

  • Print tiny labels with vinyl tape, wrap them around the wire like a flag, then cover with clear heat shrink to hold it all down.

Agreed—zip-tie labels get the job done, but they’re a last resort. Heat shrink looks pro and won’t rattle loose.

3. In this build, we didn’t follow any of Mazda’s original wire colors because a few years ago I pulled all the OEM wiring out. The colors were determined by the flying lead harness provided with the Haltech PDM16. 

4. For harness layout and pinouts, we used Excel was used to make detailed tables for:

• Wire color

• Source and destination

• Pin numbers

• Notes (sensor type, shielding, etc.)

In reply to alfadriver :

In my case anything other than main jet changes for seasonal weather shifts is whizzing up a rope. The Keihin Flat Slides on my Datsun work flawlessly. 

Additionally the folks I saw on  laptops (admittedly a small sampling) seemed to be chasing problems. Said problems could have been of their own making.

In fairness I've watched people trying to get that last 1/2 horsepower out of carbs screw them up monumentally.

To me good carbs (emphasis on good) were a better solution than aftermarket EFI from that time. 

Using a label, wrapped like a flag under clear heatshrink, is an awesome solution.  Sounds like you really aren't creating diagrams but for the most part they're probably not that needed if the Haltech setup comes with pretty comprehensive wiring.  Creating a whole-car setup from scratch probably comes with different requirements.

Great feedback, thanks.

In reply to pres589 (djronnebaum) :

Oh yeah, it a super simple solution that looks great!

There was no real need for a traditional drawn out wiring diagram. We know where the harness is being ran, the physical harness is labeled, and we know the pin out of the plugs coming from each piece of hardware. We have the spreadsheet to tell us wire color, pinouts, and what is ran together. 

In reply to James Wood :

This is really cool; even for a vintage racer such as myself.

Tom1200 said:

Additionally the folks I saw on  laptops (admittedly a small sampling) seemed to be chasing problems. Said problems could have been of their own making.

I spend a lot of time on my laptop at a race weekend but it's mainly about data analysis, I'm not tuning the car.

In reply to codrus (Forum Supporter) :

The people I'm talking about were sorting the car constantly. Like I said some of it may have been them trying to get to some magical goal instead of being content with good enough.

If one is going to switch out a fuel delivery system I'd want it to work as well as the Haltech unit the OP talked about.

What was the total material cost?

Ola, LS+1 Miata (mostly track car)

In reply to olawet :

The entire package is around $12,000 (PDM, Rebel, shock travel sensors, brake pressure sensors, coolant temp, oil temp, oil pressure, Wideband,wheel speed sensors, Dash, Can Keypad, WB1, TCA 8, Wiring Harness, & connectors). The Rebel and harness can be had for $1,400. The Rebel is a cost effective solution for any LS powered car. 

Oh wow, I didn't realize you had shock travel sensors too! Faaaaaaaaancy!

In reply to Tom Suddard :

Only top teir stuff for old girl! 

James Wood said:

In reply to Tom Suddard :

Only top teir stuff for old girl! 

The system cost more than me entire race car.

Of course I have no doubt it's worth every penny given the circumstances.

Given the features, though, this seems to compete pretty favorably against a $30,000 MoTec setup, right?

In reply to Tom Suddard :

Yes, Motec = MoMoney.

In reply to Tom Suddard :

Totally, Kevin and I were discussing a Motec setup vs this one. Since he is a Motec dealer. This setup is has similar features to a $28,000 setup from Motec. 

Again people dont have to go as crazy as I went with my setup. You can buy a Rebel ECU and harness for $1400, that'll run an entire LS swap and give you want you need. Building a 40 year old GT4 pro car sounded really fun.