5 replies to this topic

[Gary G]

One of mine recently blew and I'm curious to as why it went and what its for etc? I've looked at the wiring diagrams on the TIS and I can't even find these 50amp fuses! Only the FL4, FL3 etc (big grey ones) but nothing concerning the 2 hidden under the scuttle near the wiper motor. I think they fuse the loom between the K18 (brown ECU relay in boot) and the main FL4 fuse in the front so I wonder what would cause it to blow? Perhaps a dodgy K18 relay?

[Gary G]

Right, had a play about with a few things....refitted my original throttle body and blanked off the EGR valve. Car started and idle'd fine...none of the symptoms i've previously seen occured so I thought i'd go for a test drive....

Travelled approx 300 metres before it cut out, now this time it was very much like what happened the first time and a knew straight away the fust had blown again!!

I had a closer look at the fuse holder and the wiring:


Fuse holder in situ ^

Fuse holder removed for a closer look^

2 blown 50amp fuses and the top one which has been fine^

Its the bottom one of the two that went and from what I can see the wires go to the +ve battery terminal and into the loom towards the back of the car....i'm fairly sure they go to the ECU relay in the boot. Now if this relay was faulty would it cause the fuse to blow??



Any help, comments or suggestions greatly appreciated! Cheers

Edited by Gary G, 17 September 2006 - 02:39 PM.

[Gary G]

Looks like everyones out having fun in the sun and driving their cars, except me So i'll keep talking to myself for now lol Right, it looks like the wiring goes from the battery to the 50amp maxi fuse then from there to the ECU relay in the boot. Now the relay is NO (nomally open) then when the power source runs through it (cable from battery) its contacts come together and it makes a circuit to the ECU. Now as far as I can figure, when the fuse blows the ECU relays contacts opens and hence loses contact with the ECU and the car dies! (and then wont start/turnover etc etc) If I replaced the 50amp fuse I think the car would start, idle and run fine for a limited period (previously a few hundred metres) before it blew again. Now what I need to know/find out is why this big 50amp maxi fuse near the battery is blowing!!!!??

[speedster]

Looks like everyones out having fun in the sun and driving their cars, except me So i'll keep talking to myself for now lol

Right, it looks like the wiring goes from the battery to the 50amp maxi fuse then from there to the ECU relay in the boot. Now the relay is NO (nomally open) then when the power source runs through it (cable from battery) its contacts come together and it makes a circuit to the ECU. Now as far as I can figure, when the fuse blows the ECU relays contacts opens and hence loses contact with the ECU and the car dies! (and then wont start/turnover etc etc)

If I replaced the 50amp fuse I think the car would start, idle and run fine for a limited period (previously a few hundred metres) before it blew again. Now what I need to know/find out is why this big 50amp maxi fuse near the battery is blowing!!!!??

On the NA the ECU relay is fed via a 40Amp fuse, that is the offical rating anyway. It'd be worth changing the relay first. Do you have any additional electrical equipment in the car, sound systems, George Foreman grill, etc.

[Gary G]

lol no mate. I've just found that FL4 etc are not the grey boxes lol I think its FL1 thats popped which is rated 50A on the schematics I have found and supplies the starter....perhaps there's a short to ground on that circuit

[two4oneuk]

A trick i found out when speaking to an AA man. If a fuse keeps blowing and you cannot find out why. Try a normal 12v light bulb, solder 2 wires +ve and -ve fit spade conector on other ends now stick spaded connectors into fuse holder. If you have a short the lamp will light up and if not the lamp will not light up. This hopefully will help find the fault as the bulb wont blow like the fuse. Martin