Fan failure indicator

[declanka]

Hi I have a 1990 esprit 2.2 Turbo. Though the cooling fan is kicking in when sitting in traffic, and the fan seems to be working , the fan fail warning indicator lights up as the fan switches in and out. I dont have an owners manual so dont have good wiring diagrams. I swiched around common relays to no effect. I am assuming its not the otto switch as the fan is switching in or out. As there is no ECU on this model (I think), does anyone know how it senses that the fan is operational.

[stevem]

Feast your eyes on this...........

The 3 fans each have a 12v supply from which a 'sniff' is taken from via summing diodes to a check relay. If either of the three 12v feeds has failed, or one of the diodes has failed, or a wire fallen off, or the check relay has failed.......... you get the idea.

[MrDangerUS]

Also, it is interesting how 3 fans are powered with one 2x15A relay. Note that fan #3 is fed from "both sides" trough fan#1 and #2.