keeps blowing same fuse (protected electrical sytems)

Level 2 User Joined: 18 Apr 2005 Posts: 40

my 19 16v keeps blowing the 20amp fuse second row in from the left, anyone know what this fuse is for and why it might blow?

it dosnt blow straight away but does inevitably blow and the alternator wont charge the battery properley without it, i even tryed a 30 amp fuse in there but that blew aswell, when i unplug the fuse the idle speed increases by about 100 rpm.

aswell as that now and again it will hunt on idle around 600-900 rpm then go fine then do it again etc this is usually accompanied by a missfire below 3000 rpm dosnt seem to be related to temperature, speed etc. dont know if its related to the above or not though.

any help with this would be great else i may be swayed back to another 205 gti, shame really as the 19 is probably a better all rounder.

Spammer Joined: 27 Jul 2004 Posts: 5717

which exact fuse is that ?

Forum Moderator Joined: 02 Mar 2004 Posts: 19978

get a multimeter on the battery terminals and see what the voltage is, sounds like the alts rectifier pack is away.

also don;t stick in bigger fuses as the wires like to catch fire.

Level 2 User Joined: 18 Apr 2005 Posts: 40

i only fitted the alt last week to see if i could cure the problem, i know its not a new alt but how likly is it that both have the same fault?

what does that fuse do?

if i recall the most the voltage went upto was 14.7 V.

Level 2 User Joined: 18 Apr 2005 Posts: 40

right just checked its fuse number 11 for protected engine functions, and wouldnt you know it, it dosnt appear on any of the haynes wiring diagrams Sad

looks like im going to have to get stuck in with the multimeter.

Forum Moderator Joined: 02 Mar 2004 Posts: 19978

14.7 V is fine.

What to do is go to the engine bay and lift the loom off the subframe, see if somnething has been spilt on it thats stripped the wires etc down, its not uncommon.

Or if lifting the loom makes the fuse blow then you know where to look!

Level 2 User Joined: 18 Apr 2005 Posts: 40

i have tried wobbling various wires but dosnt seem to make any difference also when the fuse is blown it idles fine with no missfiring but when the fuse is ok it has running probs, really annoying me now might get an hour to look at it later so ill give the wiring another look.