NZPC: For those who haven’t come across you yet, can you tell us what Custom Wiring Solutions specialises in?
Drew Blewett: CWS is a small automotive-based wiring shop run by me and supported by my wife, Nicole. With a background in electrical engineering, I specialise in engine-conversion wiring and custom engine harnesses for both factory and standalone aftermarket ECUs (Haltech, Link, etc.). Over the years I’ve expanded from Holden and LS V8s through to all sorts of Japanese motors, barras, and a heap of rotaries. Everyday auto electrical problems aren’t really my thing.
How did you end up specialising in automotive wiring — was it something you pursued, or did it find you?
The automotive wiring is something that’s found me through my own interest in cars. I have a long trade background in industrial electrical and instrumentation. Around 15 years ago, I Holden V6-swapped an L300 ute, and a mate suggested I should start building swap harnesses — and it’s exploded from there into what I do today, with the support of my very understanding wife.
This has been my base for the recent years, working out of a small two-car garage. I’ve just recently moved out to a six-acre block and built a dedicated workshop, where I’m able to take on more detailed builds.
You’re doing this after hours around a day job. How does that work practically, and how busy does it get?
I work a four-day week as an electrical engineer at Huntly Power Station, so Fridays are usually free to build the cool CWS stuff, with the balance of the time in the evenings. Having the new dedicated workshop is great — I’m able to get cars to me for the larger builds.
A lot of my work is mail-order based, modifying factory harnesses or building to templates on the bench. I do pick and choose what I take on. Most people are really good to deal with and understand the time it can take, along with a few good regular customers to keep happy. It’s all about balancing workload around family life, the day job, and the six acres we’ve got to look after — we’re always busy with something!
Tell us about Rhys Knauf’ AE101 Levin — how did the project come about and what was the brief when it landed with you?
Rhys and I are both on the oldschool.co.nz forum. We have a couple of mutual friends, and he happened to be just around the corner from me. After previously seeing some of the CWS wiring work, he wanted to have a chat — cue a quick visit one evening where a plan for Rhys’ vision of the car was developed.
We discussed wishlist items, practical options and budget. It was a detailed, to-the-point brief — no nonsense, all function road-going track car, and it had to look good doing it. Rhys’ engineering in the car is super tidy and so well thought out; the wiring had to match.
This car has a 2ZZ-GE swap, a Link Storm ECU, ITBs, a custom dash, steering wheel-mounted controls — the works. What did that mean for the wiring scope? And the spec sheet shows CWS engine and body loom listed as a build component. Walk us through what that actually means in practice — what did you build from scratch versus what did you use as a starting point?
The plan for the car’s wiring was simple and functional.
For the engine harness, we explored a couple of options, ranging from a full-custom, all-new build to a stripped-back, reworked factory harness. This worked out as the best way to go for the engine, as Rhys had a very good condition factory loom. This meant better value for money, and the engine wiring still follows the factory Toyota diagram with a few modifications and additional sensors now pinned to the Link G4X Storm ECU.
On the chassis side, well, nothing remained of the original, bar the taillight harness, so that’s basically a custom build front to back. Rhys sorted the mounting of the fuse and relay box along with the switch and dash panels. From there, it was measure and template, make notes … a lot of notes. The core ‘chassis’ harness was then built on the workshop bench, all left long to be finalised in the car.
Over the course of a few visits, we finalised all the wiring in the car, powered it up, and tested everything, ensuring all functions worked as they should. From there, we loaded up a base map to the ECU, verified all the sensors, and fired the engine into life, much to Rhys’ relief. I recall most of the oil staying inside the engine.
The steering wheel has indicators, lights, and other controls wired to it for road legality. How do you approach something like that — is it straightforward, or is it one of those jobs that sounds simple and isn’t?
The wheel looks simple, but it isn’t really. With the removable steering wheel, it needed a curly cord to be pluggable, with robust connections for something that’s always moving.
All your usual stalk-switch functions are now buttons on the wheel, including a neat race-type function that runs the wiper for a single cycle at the push of a button.
OEM-style neat tuck or functional race loom — what approach did you take on this car and why?
This build is a bit of a mix of both. Working with Rhys’ clear vision of what he wanted made it easy for me to map out all the technical details and functions needed to make it work. The result is a clean, tidy install that serves its purpose well.
With a street-legal track build like this, you’re essentially serving two masters — it has to pass a WOF but also perform on the circuit. How does that tension affect the way you wire a car?
For me, it’s just wires — they go from point A to B, sometimes via XYZ along the way, which can add a bit of confusion. The key thing is good planning and quality parts. I run spreadsheet pinouts that detail to/from, function, pin number and wire colour.
Were there any specific challenges on this build you didn’t expect going in? And how long did the wiring work on the Levin take from start to finish?
The challenge Rhys set was the one-button wiper function. I managed to integrate that alongside the aftermarket wiper switch now located on the rollcage switch console. Otherwise, it was a fairly straightforward build scope.
Working around my available time, I think we were a couple of months of on-and-off evenings and the odd full day on the car. This was before I had the space to take cars in-house, so it added a bit of time to the build. However, it worked in well as Rhys had plenty to progress while I sorted the wiring out.
Nowadays, I can get a build in the workshop, and something like this would be around a month from drop-off to pickup, but it all depends on the build scope; every job is different.
What’s the most common wiring mistake you see on performance cars that come to you for fixes?
Scotchlocks … they can get in the bin. Oh, and Tek screws for ground. So often I see cars with intermittent problems from bad joins and poor terminals.
Undersized wiring to heavy loads like fans and fuel pumps is a big issue. Yeah, you might have fitted a big fuel pump, but you’ve left that small factory wiring — big load = big power draw.
If someone’s planning a similar build — engine swap, standalone ECU, custom dash — what’s the one thing they should sort out in the wiring planning stage before anything else?
Map out everything you need from the car, functions and location. It’s really time-consuming to pull something apart just to rework another circuit later. It really needs to be one of the final-stage jobs once you have all the mechanicals and fabrication in place.
Plus, talk to your tuner and wiring guy together to see what hardware they recommend, from both a function and wiring capability point of view. We’re pretty spoilt for choice with quality gear these days.
When it comes to standalone ECU wiring, what are the key things that separate a clean, reliable install from one that causes headaches down the track?
Quality parts and materials, and attention to detail. A good install is put together by someone that understands the stress these cars see, not only mechanical movement, but vibration, heat and automotive fluids.
One bad join or poor connection can be an ongoing headache to diagnose. Nothing worse than an intermittent fault that cuts your weekend short or leaves you stranded.
What should someone look for when they’re trying to find a good custom wiring person — how do you know if someone actually knows what they’re doing?
Find someone who’s keen to understand your needs and wants to work with you. Check out their previous work, ask some tuning or custom shops in your area, or even social media groups.
Good guys have a good reputation and stand by what they do. This sort of custom build isn’t your everyday auto sparky type of thing.
Is there anything about automotive wiring that most enthusiasts get wrong or misunderstand — something you wish people knew before they started modifying things themselves?
One of the recurring issues I see is people going off and buying a whole lot of parts before getting a plan or understanding what they actually need. Yeah, that shiny new ECU looks cool, but will it actually run your engine?
It’s far easier when the customer reaches out upfront for advice; they get a better outcome and quite often for less expense, especially if you’re not buying things twice.
What kind of builds are you taking on at the moment, and is there a dream project you’d love to get through the door?
I have a very cool RX3 build in the workshop at the moment but can’t say much on that — other than watch this space. Lots of conversion harnesses for LS, Holden and Ford engines always coming in and out, along with custom builds spread amongst them.
Having worked on some very cool cars in recent years, it’s hard to pick a dream project. Probably my own car, a turbo inline-six VK Commodore, which has had a lot of work as a showpiece for what I can do now, running a Link Xtreme and concentric twisted motorsport-spec harness.
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If you’re planning an engine swap, standalone ECU setup, or full custom wiring job, getting it right the first time makes all the difference. For professional automotive wiring, custom looms, and engine conversion solutions, check out Custom Wiring Solutions at customwiringsolutions.co.nz
