Daimler gauge repair

May 9, 2026

My Daimler Double-Six, along with all Series 1 XJ’s and derivatives has four gauges in the centre of the dashboard above the rocker switches. These are:

Voltage
Oil Pressure
Water Temperature
Fuel

They had all stopped working and I wanted to get them to work again, especially the water temperature one. I quickly ruled out a blown fuse, as many other things in the car that share a fuse with these gauges were working.

My next suspicion was that the voltage stabilizer had stopped working. Most of these smiths gauges run off 10 volts instead of 12, and voltage stabilizer converts from 12 to 10. I’m not exactly sure the reason for this, but If I had to guess its because they require the voltage to be consistent and normally voltage levels in a car range from 12-14 volts. I ordered one.

I also purchased the Jaguar XJ wiring diagram book and on examining the diagrams, it quickly became apparent that it probably wasn’t the voltage stabilizer. The voltage gauge needs the raw voltage in order to work, and it was also dead.

Illumination was working when the headlights were switched on, so it also seemed unlikely a problem with a bad ground. This made me suspect a problem with the power feed into this gauge pod.

Looking at what is going on is quite easy on a series 1. The panel with the gauges is hinged and folds down to reveal the fuse boxes. This was a design used on the Mark 2, The E-Types, S-Type, Series 1 XJ and probably the Mark X.

Instead of using wires for each gauge like in a series 1 E-Type, there is a flexible printed circuit board behind all four gauges and the clock. This was quite an advanced design in 1968. I doubt the people who designed it were thinking about it being in service 50 years later. The gauges are not especially complex and simple wires would be easier!

My next theory was that there was an issue with this circuit board. That proved to be the case. Inspecting it carefully, the track that takes the main power feed had burned up and so therefore power was not getting to the gauge set. The photo below shows the burned track in the mirror.

The fuse that controls the gauges plus many other things is a 35A fuse, so the tracks on this board are more sensitive than the fuse is. I suspect I caused the problem as I had been using a multimeter to see where the aftermarket radio was wired into the fuse box the day before. At the time, I probably touched something and cause a small short, and since the fuse is so large, burned on the tracks in the circuit board.

I thought quite a bit about options. I don’t have the skill level to repair the circuit board. However, I realized I could inject 12v to the line that came from the circuit board to the voltage stabilizer. This would be completely reversable if I ever got another board, and quite simple. They way the plug to the board worked, I could push a spade connector into the back of the plug where the main power feed was, and piggyback it to the line to the stabilizer. This would both power the 12v circuit before the stabilizer and bypass the burned track.

This fix seems to have worked quite well, and my gauges are back to how they were before. That is, Temperature and Oil Pressure seemingly working well. Voltage working but reading a bit low, and petrol reading very low.