Good old Citroen electrics

[mnde]

Yesterday when I started my BX after work, the coolant level, hydraulic level/pressure, STOP and oil low level warning lights remained lit and eventually extinguished after 10 mins of driving. I have established that the coolant level is correct, the oil level is at the MAX notch of the dipstick, and there's plenty of LHM. After that one time, it hasn't happened again... I'm suspecting it's got something to do with the huge downpour we had yesterday morning and a spot of damp was causing a short somewhere. Time to get out the WD-40 and start spraying. Are the "low coolant" and "low oil" lights connected in series with the STOP light, as the hydraulic light is? I don't want my warning lights starting to play silly buggers warning me of non-existent faults....

Cheers,

Mark.

[AlanS]

I had a similar one on my BX Estate a while back.
It would light up everything and being in Oz I also had the addition of a nice noisy warning buzzer which in one instance lasted for 45 minutes on a drive home one night. Where mine was such a thrill was that it usually came on as I came to an corner as the auto changed back to first gear and would stay on usually until I turned the engine off, waited anything from 5 to 30 minutes and then be right again. We tested relays, earths you name it and even began wondering if there was some kind of electronics involved with the auto we didn't know about.
Eventually, we discovered by accident, that we had a short in the oil pressure warning sender.
Replaced that and problem all gone. Just another to add to the list to check.


Alan S

[AndersDK]

Common problem over here our ways - with salty winter roads.
Problem is caused by the sensor wires from the coolant level sensor to the Valeo relay going open circuited because of corrosion.

The relay is not a relay - but a small electronic circuit which constantly monitors a medium ohmic resistance between the coolant level sensor pins. This is the resistance through the coolant.
If the sensor pins gets dry (low level) or the sensor wiring gets disrupted - a high ohmic resistance now exists on the 2 wire input to the circuit - thus the coolant low level fault lamp is set.

This means : NEVER ignore the fault lamp despite no obvious problems found. There really is a reason why you get the fault lamp on.

The engine oil and the coolant level warning lamps - are wired together by diode circuits (in the instrument cluster) which then sets all 4 warning lamps (oil, coolant, hydraulic and master caution STOP) if either engine oil or coolant level fault is present. This is to be sure your attention is drawn at the problem - because both fault types are potential fatal to your engine - and thus your wallet

[Doz]

altogether now ...

"They all do that sir"

Mine did it a few months ago after changing my carb. I'd got water on the wiring loom from the auto choke water pipes. It is most disconcerting though.
always best to pull over and check.