Fuse blowing intermittently

[YellowstoneYeti]

I have a 98 Legacy Brighton wagon, 2.2L, 5 speed that I've had for
about 4 years. After having the car for about a year, it blew the
15amp E/G IGN SRS Airbag fuse, causing the car to stall and not re-
start until it was replaced. Another year went by and it happened
again. It has slowly been happening a little more often. Lately it has
been blowing every 2 weeks to a month. At first, I'd just replace the
fuse and be on my way. The last 2 or 3 times it happened, it will
instantly blow 4 or 5 fuses before the car will start and run. There
doesn't seem to be any common thread as to why it blows. It has me and
the local mechanics stumped. The nearest knowledgeable Subaru mechanic
is 100 miles away. Has anyone ever had this problem? Anyone have any
ideas on what to look for? Any suggestions would be appreciated. Thanks

 

[Stewart DIBBS]

...The last 2 or 3 times it happened, it will instantly blow 4 or 5 fuses

OK, there's clearly an occasional short circuit somewhere. I don't have a
Subaru, but offer the following suggestions.

The fuse is listed as E/G IGN SRS. This suggests to me that the fuse
protects three items: E/G, IGN and SRS (Airbag system). IGN is clear
enough, as is SRS. I don't know what E/G stands for: do you? (Engine,
Environment, Entertainment, G???)

Anyway, IGN will be passing power to the ECU most likely through a relay or
two, and also to the SRS controller. Since this fuse blowing is getting
worse, the short is intermittant. Electrolytic caps in controller boxes are
a source of unexplained sudden shorts.

Most likely scenario:
Find and remove the ECU box and open the can. Have a sniff for something
that smells sort of fishy. Leaking electro caps often have the top or base
popped out, or you can see leaking whitish electrolyte. A bad cap on the ECU
would explain why the engine won't run and why you need multiple fuses. The
good news is that replacing caps is not hard, you just have to be careful in
desoldering them. You might also consider locating a spare ECU from a
wrecker. There are also people on the net who repair / exchange ECU's.

Less likely:
You could locate the SRS controller box and disconnect it. DO NOT DISCONNECT
THE AIR BAG DIRECTLY (these have yellow connectors I think) unless you want
to risk setting it off via static discharge: Just disconnect the power to
the controller box. I doubt it's the SRS system.

If you can identify what E/G means eg by pulling the fuse and seeing what
else won't work, isolate and check these items if possible, for bad grounds
or potential shorts.

Lastly, its not impossible the you have a short inside a wiring harness.
These can be really hard to find until the short generates enough heat to
melt something ...

SD