Ultra Gauge Installation

The instrument cluster used in the TDCi Defender is the same as that used in the Discovery 3 and Freelander 2. Both of these vehicles have trip computers, however is was omitted on the Defender, possibly to avoid scaring some of the more traditional Defender drivers with "that electronic voodoo magic", but more likely to keep cost and complexity down.

The Discovery 3 cluster is shown here:

In order to add a trip computer feature to the Defender, I considered both the Scan Gauge and the  UltraGauge as possible plug & play solutions.

My aim with the Defender is to keep the look of it as OEM (Original Equipment Manufacturer) as possible. Having assessed the screen sizes of both devices, the Ultra Gauge easily looked like the better fit for the instrument cluster.

The UltraGauge is an OBDII Scan Tool and an Information center that, on the 2.4 Puma Defender, displays 49 of a possible 78 selectable engine gauges.  The gauges include parameters like RPM, Engine Temperature, Intake Air temperature, Speed, Distance, Intake Pressure, Mass Air Flow etc.  UltraGauge can display an assortment of mileage gauges including Instantaneous MPG, Average MPG, Trip gauges.  UltraGauge can scan and read vehicle trouble codes and can even display potential trouble codes. 

The first job was to remove the screen and electronics from the enclosure to assess the dimensions and wiring. I de-soldered the screen from the PCB assembly, but this isn't completely necessary:

Using the screen as a template, the dial fascia was marked out to be trimmed back:

There are more detailed pictures of the dash in various states of disassembly on my blog post about the Check Temp III Install On removal of the excess fascia, a matrix of light guides for LEDs can be seen with three LEDs on the bottom row:

2 of the LEDs have symbols on the facia for what appears to be the DPF. The 2.4 TDCi does not have one, so it is OK to leave these hidden behind the screen. Unfortunately this means that this modification would require a bit more engineering to complete on a more modern 2.2 TDCi with DPF.

 The main cluster PCB was removed from the main dash support and a manual milling machine was used to cut the hole to fit the UltraGauge screen. A Dremel type tool could be used here, but wouldn't be as tidy. If using a Dremel, the dial fascia should be removed to avoid damage - it can then be replaced to cover any mistakes.

The new aperture can be seen here:

The aperture was gradually enlarged until it was a neat fit for the screen.

The rear of the aperture is shown here with the dial surround fitted.

In order to get the OBD cable into the dash, it had to be disconnected from the PCB assembly. This picture was take for reference to not the order of the wire colours. The silkscreen (white writing) on the PCB shows which colour of wire should be placed on which solder pad.

The cable shown disconnected from the PCB assembly:

 The screen and PCB were reassembled and located into the cut out. At this stage a bit of fine trimming was required to fit the assembly:

 Hot melt glue was used to secure the UltraGauge internals.

2 holes were drilled in the bottom of the cluster assembly to allow the OBD cable and a button relocation cable to be attached. Both cables were soldered on to the PCB and secured with some hot melt glue.
The cable for the buttons is a butchered USB (Printer) cable. Having checked each push button, they all share a common ground, so only four cores are required.  

 The cluster was reassembled and tested before the final fit:

Some push button switched were wired, soldered and heat shrinked to extend the switched on the back of the Ultragauge that are now inaccessible.

The steering column shroud was removed to locate the 3 switches, similar to the CheckTemp installation.

The switches are mounted in a 12mm hole and attached using a plastic nut.

                                      

By keeping the wires for each switch separate, each fully terminated switch loom can be passed through the correct hole and clicked into the 6 way connector block shown below:

The reassembled instrument cluster can be seen here - the 4 wire USB cable was replaced with 6 discrete wires twisted together.

This shows a close up of the wiring entering the bottom of the cluster.

The connector for the switches mean that the cluster or the steering column shroud can be removed in future without cutting or de-soldering any wiring.

The switches are shown here mounted on the steering column shroud. From left to right the functions are 'UP', 'MENU', 'DOWN'.

The final result is shown here. The Ultra Gauge screen is an excellent fit for the Defender cluster.

A piece of transparent apple green sticky back plastic was placed over the screen to bring the colour of the display closer to that of the other gauges.

Update 23/10/2014:

By blending different filters, a more accurate match for the standard colour was achieved. There are a total of 5 layers of filter plastic to get the look below: