Nissan Sunny B12 Rz-1 Digital Speed Sensor

Today I finally managed to measure the signals on the digital speed sensor. I don’t own any of the Rz-1 digital cluster parts, but luckily, a friend borrowed me his sensor and allowed me to reverse-engineer it.

The speed sensor has a connector with three pins: black (right), yellow (middle), red (left).

Based on what I measured, black is GND, red is +5V supply, and yellow is the speedometer signal. The based on my scope prints, it seems that per revolution of the speedo cable we can see 24 pulses:

When I rotate the pin of the speed sensor at about one revolution per two seconds, the cluster shows me – very roughly – 13 km/h.

When only connecting the +5V and GND, but leaving the signal pin open. the signal looks idential. When rotating the pin of the sensor, the 5V pulses on the signal line are still visible.

Therefore, it seems we can just use a 0-5V PWM, and bring it onto the cluster, and it should display the speed signal.

Nissan Rz1 Digital Cluster Conversion

A few years ago, I modified a LHD Nissan Sunny B12 Coupé Rz1 and fitted a RHD JDM digital clusters, and uploaded a short video of it on youtube.

I received a lot of questions on this modification, and decided to publish the knowledge I gained here.
Most importantly, here is the pinout.

Pinout Comparison of the RHD JDM loom and the LHD EUDM/USDM loom

Connector Pinout

The connectors are drawn on the left side. Basically, you see five connectors here. Connector “A”, “B”, and “C” under the header “Digitaltachostecker” describe the connector of the digital cluster. Connector “A” is the large one that powers the talltales and warning lights, connector “B” is the hard-to-find black one, that provides all the actual digital signals. The three-pin connector “C” can not be found on the cluster, but is the connector on the tachometer sensor in the engine bay (you need that part too).

The connectors labeled with “EU stecker” refer to the ones that you will find in your LHD Rz1s that came with analog clusters. You should most likely find them in your car if you remove the cluster.

In case you have a low-end spec B12 that came without a rpm gauge (some U.S. Sentras maybe?), your connector layout is probably different again.

The drawings show the connectors (sockets) on the cluster, as if you look on the backside of the cluster. They do not show the connectors on the harness!

The first problem you’ll face is that you need to get the small connector “B”, which, if it is not attached to your digital cluster, is pretty much unobtanium. You could try to find the original part number or a the part number from the supplier who made this connector, or in the worst case, replace the connector with a diffent type of similar size / pin cont and just solder everything together.
The white, larger connector “A” is physically identical to connector “A” of your LHD harness, but with a different pinout.

You got your hands on some plugs? Good, then you can already solder everything together, and your digital cluster should already party come to life. PRM, turn indicators, telltales (except exhaust temperature), temperatur gauge and fuel should come to life.

Vehicle Speed Sensor

The next difficult task it to get a speed sensor. The analog clusters uses a mechanical speedo cable that connects the gearbox to the speedo pointer – that is 100% mechanical oldschoolness!

For the digital cluster, NISSAN chose to go half they way – they still use a mechanical cable, about 50 cm long, that connects the gearbox to an electrical sensor. That sensor converts the motion into PWM signals, that are electrically supplied to the cluster. For the conversion, you will need both the cable and the sensor. If you don’t have these parts, then the installation will be a bit more difficult. They will plug&play fit to any gearbox.
The digital sensor is connected with two cables, C2 and C3, to the main plug of the cluster. So you will need to add two wires from your engine bay to your cluster.

If I remember correctly, the speedo singal is triggered twice per revolution. If you don’t have a sensor, you might want to use a function generator and try to get your cluster displaying something. If you are struggling here, feel free to leave a comment, then I will look up the technical details.

From the youtube comments on my channel, I understood that there seem to be different types of sensors, depending on which engine / gearbox your donor car had. It is likely that non-matching gearboxes will provide false readings on the speedo! If this is the case, then you would need to invest more engineering into the problem, e.g. use a small microcontroller to correct the signal.

I once tried to fit a digital sensor from the B13/N14 series into an E16i gearbox, but they wouldn’t fix plug&play. The main problem was that while the diameter was the same, the axis of the sensor was slightly offset. With some fiddling you might be able to mount them, though.
These sensors might fit for the GA16i gearbox, though. If you tried going this way, please leave a comment and share your experiences! it would definitely be cleaner looking than the OEM B12 parts.

You will have to figure out a solution to mount the speedo sensor in your engine bay, as the LHD / RHD firewalls are different. I suggest to use a little metal plate to mount the sensor to, and then adapt that to the firewall.

Incorrect mounting with too much tension on the cable might lead to the speedo not working at all, faster wear-out or not working at all.

Fuel Level Sensor

A problem which is not yet solved, it the fuel gauge. The fuel sensors used in the JDM digital cluster cars have a different characteristic.

The analog clusters use an 8V voltage regulator, which is connected to the fuel gauge and the fuel sensor in series. The resistor value of the LHD fuel sensor is as follows:

Resistor Value [Ohm] Displayed Fuel Level
2,4 110%
11,8 100% (full)
21 77%
35,748%
61,825%
80,65%
87-1%

The digital cluster characteristic is quite different. I used a JDM cluster and measured the fuel input. The fuel sensor is supplied by 5V, and depending on the resistor values, the following fuel level is displayed:

Resistor Value [Ohm] Number of bars
14,9 14 (full)
20,414 (full)
23,613
30,613
7810
1058
2166
3004
4003
6002
7171
8091
10000 (empty)

With this information, you should be able to build your own adapter for the fuel sensor.