Why let the Nexus run the wipers?
A classic wiper circuit uses a multi-position switch, a slow winding, a fast winding and a park contact to stop the blades at the bottom of the glass. When you rewire an old car around a Nexus VCU or a PD16, you can drop most of that. The Haltech drives the motor from a half bridge output (HBO/HCO) using PWM, so it can set any speed it likes through one winding. You wire only the high speed winding and leave the low speed winding disconnected. Slow sweeps are simply a lower duty on the fast winding.
The result is fewer wires, any switch you like on the dash, and wiper behavior you can change in software instead of with a soldering iron.
Datsun 1200 motor connections
The Datsun motor has five terminals, A to E. Here's what each one does and where it goes:
| Motor terminal | Inside the motor | Connect to |
|---|---|---|
| A | Fast (high speed) winding | A spare half bridge output (HBO/HCO) on the Nexus or PD16 |
| B | Slow (low speed) winding | Leave unconnected |
| C | Motor ground | Battery ground |
| D | Park switch | A spare AVI |
| E | Supply | Ignition-switched 12V |
Set a multimeter to resistance and measure each winding terminal against ground. The fast winding reads the lower resistance of the two. This matters on any motor where the pins aren't labeled or the plug has been replaced.
The same method works for most two-speed permanent magnet wiper motors, not just the Datsun. Identify the fast winding, ground and park contact, and the rest of the setup is identical. For the broader feature overview, see our windshield wipers article.
Setting it up in NSP
Turn on the Windscreen Wipers function in the Electrical section. That unlocks a wiring page where you choose which switch inputs you want and then assign the pins.
Choose your driver controls
| Setting | What it adds | Our advice |
|---|---|---|
| Front Low Speed Enable | A switch input for slow continuous wiping | Enable it if your switch has a separate low position |
| Front Off Input Enable | An input that tells the wipers to go home and stay parked | Useful with multi-position switches that have a dedicated off contact |
| Front Hold To Swipe Input Enable | Full speed only while a momentary button is held, off once released | Great for race cars that just need a quick clear |
| Front Intermittent Mode | How the delay mode behaves | See the options below |
| Rear Mode | Whether a rear wiper exists and how it's triggered | Leave disabled on a sedan or coupe with no rear wiper |
Intermittent options
- Off: no intermittent mode, and the intermittent input disappears from the wiring page.
- Single Speed: a fixed pause between sweeps.
- Slow when Stopped: the pause stretches out while the car is standing still, which is how many modern cars behave at traffic lights.
- Voltage Input: a variable voltage input, like a potentiometer on the dash, sets the delay. This unlocks the intermittent voltage settings.
Rear wiper options
- Disabled: hides the rear park input, rear wiper output and rear full speed input.
- Rear Wiper Input: the rear wiper runs from its own switch.
- Follow Front When Reversing: if the front wipers are going and you select reverse, the rear wiper joins in.
Assign the pins
Each item below appears once its feature is enabled. Use Assign to pick a pin and Clear to remove it. Switch inputs also offer Conditional, which lets you drive that request from a generic condition instead of a physical switch.
- Front Wiper Output: must be a half bridge output. This is terminal A on the Datsun motor.
- Front Park Input: the park contact that tells the Haltech the blades are at rest. This is terminal D.
- Front Full Speed, Low Speed, Intermittent, Off and Hold To Swipe inputs: your dash switch positions.
- Rear Wiper Output (half bridge), Rear Park Input and Rear Full Speed Input: only if you run a rear wiper.
A worked example
Say you're building a Datsun 1200 with a Nexus and a three-position toggle: off, intermittent, fast. Wire terminal A to a spare half bridge, D to a spare AVI, C to ground and E to ignition 12V. Enable Front Off Input and set Front Intermittent Mode to Slow when Stopped. Assign the toggle's three contacts to Front Off, Front Intermittent and Front Full Speed. Now you have a delay mode that relaxes at lights, a fast mode for heavy rain, and blades that always park at the bottom.
Troubleshooting
| Symptom | Usually |
|---|---|
| Wipers run slowly even on full speed | The low speed winding (B) was wired instead of the fast one (A) |
| Blades stop mid-glass | Park input not assigned, or the park contact is wired to the wrong pin |
| Can't select the output | The chosen pin isn't a half bridge output |
| Intermittent input missing from the list | Front Intermittent Mode is set to Off |
FAQ
Can a Nexus ECU run wipers without a PD16?
Yes, as long as it has a spare half bridge output. The PD16 is handy when the VCU's outputs are already spoken for.
Do I still need the factory wiper relay?
No. The half bridge output drives the motor directly and handles speed through PWM.
Planning a full classic rewire? Book a free consultation and we'll help you lay out the inputs and outputs.
