U C I   R A C E C A R   2 0 2 3
UNIT TESTING
Updated 2/6/2023
Purpose: Evaluate the condition of the instrument cluster & test the trouble lights OFF THE VEHICLE.
Goal: Provide a way to manually turn on/off selected trouble lights and gauges.
Nissan 240SX Instrument Cluster

Really hard to work on in the car!		 Nissan Instrument Cluster

Tools:

 

Bench Testing: Nissan Instrument Cluster


The test bench includes:

  • Power Supply (12VDC) to function as the car battery
  • Dash Cluster Unit
  • Custom circuit board exerciser
  
Rear View of the cluster. Here you can see the flexible circuit board.

The traces are formed on a flexible, plastic sheet. This way, it can conform to the shape of the cluster and allows for the trouble lights to fasten directly to the traces. This creates a clean installation. It also makes it easy to trace each circuit.

The large white & black connectors provide power, ground, and sensor signals to and from the car's electronic control units.

I attached the red wire at the bottom to my B+ power supply post. It provides 12VDC to the "ignition ON" circuit of the cluster.
Most of the instruments/lights only function with the key on.
This image shows the perfboard I used to hold the slide switches and connections to the cluster.

To activate most gauges & dash lights, a B- or ground connection is required.

My slide switches connect one side of the lights to B- via the power supply.
Here is a top view of the board.

The black binding post is connected to the B- post on the power supply.

When a switch is thrown, it connects one end of a specific dash light to ground. Each of the colored wires is connected to the cluster wire harness and provides a ground to a specific light/gauge.

The B+ is supplied directly to the cluster as shown above.

So, a light is connected to B+ directly on the flexible circuit board and my switches provide a ground in order to complete the circuit.
The rear view of my perfboard shows how I connected each harness wire to a specific switch. I used a wire-wrap tool to connect my small colored wires to the jumpers that were soldered to the board.

All of the switches have their center pins connected together and to the binding post which supplies the B- power connection.		  
A side view shows the wiring between my board and the cluster wiring loom.  
Finally!!  Here you can see that several of the lights and the brake warning light have been activated sucessfully.
Here is my wiring summary. This can serve as a TSB (Technical Service Bulletin) for future teams and be integrated into your design reviews.
QV Instrument Cluster: 94 Nissan 240SX
BLK CONN My
Description B+ B- Color Jumpers Switch#
Seat Belt warning light IGNITION POWER 13 Wht Conn Yellow-Blue GREEN 1
Door Ajar light IGNITION POWER 7 Blk Conn Red-White ORANGE 2
Alternator Warning light IGNITION POWER 12 Blk Conn White-Red BLUE 3
Low Fuel IGNITION POWER 24 Wht Conn Red-Blk YELLOW 4
Oil Indicator IGNITION POWER 11 Blk Conn Yellow PURPLE 5
Parking Brake Light IGNITION POWER 5 Blk Conn Yellow-Red WHITE 6
Check Engine Light IGNITION POWER 16 Wht Conn Red GRAY 7
IGNITION POWER 17 Wht Conn
GAUGE POWER* 18 Wht Conn
Fuel Gauge GAUGE POWER 15 Wht Conn Green
Temp Gauge GAUGE POWER 19 Wht Conn Blue-Blk
Tach Signal Line PWM 0-300Hz Sq Wave GAUGE POWER 9 Blk Conn White-Red
Tach Ground 8 Blk Conn Blk
*Gauges need ign power also
BLACK CONN WHITE CONN
Supply Power on specific lines for these features Use ignition power pin #17 for most of the LED's
Ground #8 for Tach
#9 = PWM Tach Signal