Since arriving back in Ireland, we’ve mostly been getting by without a car, while awaiting the arrival of our car from Japan. However, for the past couple of weeks we’ve benefited from the generosity of my stepmother, who has been kind enough to lend us her car while on holiday in Canada.
The car had one minor problem which she asked me to look at if I had the chance: the mileometer/odometer display was faulty.
It’s an LCD 7-segment display of the kind used in calculators, and I’ve seen calculators with the same fault. The calculation works fine, but the display is faulty.
I figured that if I could get at the connectors at the edge of the display, I could inspect them and clean them and see if there was any obvious problem, such as a short circuit due to dirt or condensation, or dry (cracked) solder joints.
First I had to remove the instrument panel from the car. This turned out to be quite easy and straightforward.
The instrument panel plastic surround is held in place by three screws (Phillips #2) along the underside of the upper shade.
This plastic surround is connected to the plastic upper cover of the steering column, which is held in place by a clip on each side and is easily removed using a flat-bladed screwdriver.
The plastic surround contains the electric boot release switch, so this had to be disconnected before it could be pulled free.
Now that’s out of the way, the instrument panel itself is held in place by another four Phillips screws – 2 at the bottom and 1 each at the right and left.
Once these screws are removed, the whole panel can be pulled out and forward, allowing access to the wiring connection at the back. It’s probably a good idea to turn off the ignition before disconnecting the instruments.
The plug is secured in place by an ingenious clamping arrangement, released by sliding the black plastic clamp to the left.
Now the whole instrument panel can be lifted out. Good idea to put it face down on a newspaper or cloth to protect the lens from getting scratched.
The back cover was held in place by 2 screws (Torx 10) and 4 clips around the outside. Removing the back cover exposed the printed circuit board (PCB). You can see a lot of brownish corrosion around some of the connectors, especially in the area directly behind the LCD display (top right of this picture).
The front cover (including the lens) is only held in place by plastic clips and is easily removed, exposing the gauges.
At this point, before removing the needles from the gauges, I took the precaution of taking a photo of the position of each one, so that I could return it to the same position. Another idea would be to mark the position with tape.
After removing the 4 needles (temp, tach, speed and fuel), and 5 more Torx screws holding the front panel in place, I was able to lift off the front panel, with the intention of accessing the faulty LCD.
With the front panel removed, it looked like this:
Unfortunately, at this point I was not able to make any further progress in dismantling the LCD unit itself. My intention had been to inspect and clean the connectors.
However, I was able to clean the back of the PCB by spraying it with WD40 and rubbing with cotton buds. This was effective in removing a lot of the visible corrosion around the connectors.
I also used a hairdryer on the PCB for a few minutes – partly to dry it off and also with the idea that it might help to repair any dry solder joints. Although a hairdryer probably isn’t hot enough to reflow solder, I thought even softening the solder might help somewhat.
Finally, I reassembled the whole thing and mounted it back in the car. And to my very pleasant surprise, it works!