05 Yaris alternator fuse problem

[Fateguard]

[Intro]

My car is 2005 yaris, with 1.4l D4D engine. A few months ago turbo was leaking oil, but that got fixed. I've also had some wiring problems(taillights). I also got conditioner refilled a week ago. But other than that it's a regular daily driven car.

[Issue]

Prior to the main problem I've noticed that when I turn the key to start the engine, startup sounded/seemed somewhat weaker and after it's started (cold engine, well as cold as it can be during summer) while idling it would randomly drop RPM for a few second then rise back up, repeats until the engine heats up (after roughly 5-10km). So the main issue then.. Yesterday I was on a road trip, went completely normal for around 100-120km, then I had to make a stop. Turned off the engine, it was turned off for about 20-25 minutes. When I came back to continue driving. I tried starting it as usual. I turn the key, dash, radio, air, etc turn on for a second or two, then I turn the key further to start the engine and everything except headlights and interior roof lights died, however the engine did start and sounded normal. Then I turned it off and checked all fuses, the only one that was blown was the "ALT 120AMP" fuse (I for some reason had 100amp fuse in that spot). Tried bridging the connection with ~200amp wire and that blew in 1-3seconds. (Tried the wire a few times) After 3rd one there was very small amount of smoke coming from under the "on top of the engine mounted radiator". I don't have any decent enough knowledge to assume anything, but I am thinking that it might be related to alternator.

[Help?]

Has anyone dealt with this kind of thing? If so, maybe you could help me figure this out?

[stantheman1]

I think the fire brigade have dealt with a few! But seriously you should NEVER bridge a fuse as they ALWAYS blow for a reason, you may have caused permanent damage to the wiring/electrical components.Electrical diagnosis from a professional is a must.

The original fault sounds to me to be like a failing Battery (the lower Battery voltage would cause a higher current draw from its equipment). You should avoid staring the vehicle when other electrical loads in the on position as well as doing so creates a larger volt drop on the Battery.

[Fateguard]

@stantheman1 I know that bridging a fuse isn't a good idea, but I had no alternative choice as I was ~100km from home.. In any case today I checked the Battery voltage and it's at 12.65, so I think it's safe to say it's not the Battery

[stantheman1]

Did you load test the Battery? A Battery may appear okay without any load.

[flash22]

if its the alternator fuse the alternator has gone bad, a bad rectifier pack will do all sorts of things also check the wiring to the starter

[Fateguard]

@stantheman1Today I tested as much as I could. Didn't find much. Except that when I unplug this wire everything works, but I have no clue what this wire goes to... Maybe you happen to know?

[flash22]

What wire are you referring too ?

[Fateguard]

@flash22 

[flash22]

Does the car start with it disconnected ? Does the Battery light stay on ? If so it's the alternator cable

[Fateguard]

@flash22 Why would that be the alternator? 1st I did full inspection of alternator and it's in perfect condition. 2nd When this is disconnected car works as if nothing AT ALL is wrong. I'm just wondering if I can run it with that disconnected or not and what's it from

[flash22]

What plugs into it ?

Edit. Forgot it's a diesel it's likely the glow plug power

[Fateguard]

Thank you, will check that as soon as I can

Edit-1: But how does it start with them unplugged?

Edit-2: As I've said with that wire unplugged it engine runs perfectly fine and all electronics are working.

[flash22]

The only info i have is for p1 petrols yours being LHD im not able to find that plug makes it specific to a diesel, The only high current devices will be the alternator, fuse boxes, starter and Glow plugs/relay

[Fateguard]

Today I've tested the Battery, alternator, all of alternators wires, charging current, all connections that are in engine bay... Tried to trace the wire that is causing a short, but it vanishes in the firewall. Learned a new thing, if I start the car with said wire unplugged and plug it after a minute or so, there is no short. Anyone got ideas?

[stantheman1]

It would make sense if it was the power feed to the glow plugs as you'll be able to start the engine due to it being relatively warm, (it would be a different story in winter) also the glow plugs would be 'out of circuit' when engine is slightly warm so by plugging the connector in after a minute or so would explain why there's no short circuit. You still need to sort it though.

[flash22]

It's either the relay or a failed heater, but a bad heater would make sense - its easy enough to check with a meter

[Fateguard]

@flash22 A bad heater? You mean the interior heater?

[stantheman1]

No, he means a bad heater on one or more of your glowplugs.

[flash22]

A Bad glow plug, they eventual just burn out and either go open or dead short