Keep Blowing Fan Fuse Any Ideas?

[pugpete1108 62 1 Cars]

had my pug out of the garage on its own steam today and have got it idling sweet but for some reason the fan fuse (20a) keeps blowing and when i switch the manual fan switch it primes the fuel pump??

 

now i have had no trouble with this before now and have changed no wiring at all....but i ran the car up to temperature fully today and the fan kicked in for the first time through the ecu, could this be the cause i wonder?

 

running megasquirt managment btw

 

[Cameron 16]

Might be a silly question, but have you wired the relays as they appear in the diagrams or by pin number? What I mean is, the pin layout of a standard relay isn't what you have in the diagrams. The coil terminals are opposite each other, and switched terminals opposite each other, rather than next to each other like in your diagram.

Edited September 28, 2009 by Cameron

[pugpete1108 62 1 Cars]

i'm pretty sure i wired it by the pin numbers, will have to double check.

 

wierd thing is when i turn the switch to perm earth (fan on constant) the fuel pump re-primes which would indicate that the ecu is resetting and re-priming the pump,this is even with the fuse removed??? if i remove the fan relay it doesnt do it. maybe a knackered relay? its nigh on brand new though.

 

gonna have to dig out the multimeter again and run over the wiring

[pugpete1108 62 1 Cars]

right been over the wiring and it all seems in order (earths all good and 12v going to the right places at the right times)

 

but still when i switch the fan over to manual it reprimes the fuel pump (possibly resetting the ecu)

 

i have the fan manual switch earthing through the main ecu earth so this will be my next guess. i'm gonna give it it's own dedicated earth and see if that helps?