Xantia fusebox failure

[xantia_v6]

Last week in France, after sitting outside for 3 weeks in very hot weather, on the day we were due to drive back to the UK, the Xantia V6 failed to proceed.

When turning on the ignition, only the charging warning light came on, no fuel gauge and no starter, but I could hear the fuel pump running.
A quick perusal of the handbook showed that the gauges are fed by F12, so that was checked and found to be OK. On a hunch, I pulled out the starter inhibit relay (lucky I remembered which one it is) and bypassed it, and then found that the engine would start.
After mucking about for some time getting nowhere, I tried bodging a feed into the live side of F12, and the gauges and A/C sprang into life (it was about 35 degrees outside the car and 45 degrees inside by this time).

So I drove it 500 miles home in that condition, never missing a beat. On checking the wiring diagrams it looked as if a fault that lost power to F12, but still let the engine run must be internal to the fusebox.

I found the correct fusebox in a scrapyard yesterday and fitted it, and everything is returned to normal.

I opened up the old unit, but could not see any fault until viewing with strong magnification: (sorry about the uncropped picture, scroll to the bottom right)



Amazing that it worked happily for 15 years before a sudden catastrophic failure.

[Hell Razor5543]

Dig out the soldering iron. That is repairable, and well worth doing.

About 15 years ago a company I worked for had several Goldstar (now LG) monitors. One of them failed (thin horizontal line in the middle of the screen). As we had a few spares I swapped it out, and thought nothing of it until a few months later another monitor failed the same way. I decided to investigate, and found that, on the base of the connector that drove the scan coils, there were several joints that had failed like the one in your picture. I did not find any other failed joints, so I re-soldered them, and both monitors came back to life. I investigated all the other Goldstar monitors and found signs the joints were failing. I re-did them all, and then (a few years later) when 1 monitor did the same, I re-did them all again.

[xantia_v6]

I have seen similar fatigue failures on PCB mounted inductors, but there isn't a lot of weight or vibration here, just thermal stress.

One other notable point, you can see in the photo that the copper on the PCB has been milled away, not etched. I suppose due to it being extra thick copper, but it looks like an expensive way to make it.

[CitroJim]

Excellent stuff Mike, that's a lovely classic dry joint there...

[MJM]

We make machinery with circuit boards fitted. My mate who does all the electronic design work curses the lead free solder used nowadays (RHOS compliant?) daily. This solder does not flow as well as the old stuff. In my opinion it is anything but environmentally friendly. The extra time and effort needed to fault find and correct is a total waste of time and material. It must lead to more resources being wasted due to early component failure and the modern way of binning the failed bit and replacing with new.