EC2-B1 and Radio fuses blow out for no reason, Help! (1 Viewer)

[DaMan]

Hi people,

My 02 Lx 470 blows out the 20A ECU-B1 and Radio fuses in the fuse box under the hood for no apparent reason. Initially I thought it was related to heavy rain but I was wrong.
And if I try to plug in a new fuse it blows out immediately. I have to unhook the battery put the new fuses in and connect the battery after.

This solves the issue, until of course it happens again.
Not sure what to look for, any hints from people? Any circuit diagrams I can look at?

The fact that disconnecting the battery allows the system to "reset" is kinda surprising to me. If there's a short circuit it should always be there.

When it happened today I was on a smooth road going 10mph so probably not a naked wire, either.

Any ideas are very appreciated. I am out of 20A fuses and just out right annoyed at the issue, it causes the radio, the key remote etc to stop working as the ECU-B2 is blown.

Regards

 

[ramangain]

Will it blow with a 30A fuse?

 

[DaMan]

Will it blow with a 30A fuse?

The last time it happened I was out of 20 A fuses so I used a 25 on the radio which is currently blown.
I wouldn't want to put a 30A and start running it, wouldn't that put the system at danger of burning out? Instead of fuses I might burn up the ECU or head unit entirely.

 

[ramangain]

You can isolate the stereo by pulling the front passenger seat and unplugging everything from the amp. Divide and conquer!

 

[DaMan]

You can isolate the stereo by pulling the front passenger seat and unplugging everything from the amp. Divide and conquer!

I can definitely try that but the issue re-appears after variable amount of time from a few months to a couple of weeks.
So not sure if I am okay with no music for a couple of months on my daily driver.

 

[ramangain]

How good are you with a DMM and the EWD?

 

[DaMan]

How good are you with a DMM and the EWD?

Good enough,
If I have some ideas on how to narrow down the culprit I should be able to.
As we stand I don't have a circuit diagram so I'm choosing not to rip open the wiring bunch going into the fuse box and following the wires from there. If I get annoyed enough this very well might end up happening

 

[jerryb]

LC but would be the same.
either nav or no nav unplug the amp first.

 

[DaMan]

One thing I forgot to mention on the first update, the last time issue happened the sound system was off. Not sure if that eliminates enough possible culprits but should help cross out a few?

I have a possible lead on the problem will update as I debug this annoyance.

@jerryb thank you very much on the help

 

[DaMan]

New development, the unplug battery put new plugs in, connect the battery formula is not working anymore, the fuses go off as soon as I connect the battery

 

[DaMan]

@ramangain tried 25A fuses same results.
Wouldn't want to push it beyond that.

 

[ramangain]

Besides the head unit, amp, and possibly CD changer, what else does the EWD show is connected to the RADIO fuse? Also, where does the RADIO fuse draw its supply from on the EWD?

 

[medtro]

I thought I saw this before. Could this be related? Did you install new USB plug?

2002 lx470 Head unit completely dead. Help!?

Hi Everyone, My head unit completely went dark after my plugged my car charger in the cigarette lighter unit. (The car still ran with no lights on the dash) On parking the car I also realized the key fob remote was not working either. Got home checked the fuses and surely the fuses for Radio...

forum.ih8mud.com

 

[DaMan]

I thought I saw this before. Could this be related? Did you install new USB plug?

2002 lx470 Head unit completely dead. Help!?

Hi Everyone, My head unit completely went dark after my plugged my car charger in the cigarette lighter unit. (The car still ran with no lights on the dash) On parking the car I also realized the key fob remote was not working either. Got home checked the fuses and surely the fuses for Radio...

forum.ih8mud.com

I did and then I removed it as the ports didn't really help power any thing I wanted, plus the cheap USB plug was the first item I wanted to remove from the equation.
The two wires that are supposed to power the cigarette lighter are protected with heat wrap.
I am seeing an interesting issue I want to bring up.

 

[DaMan]

Besides the head unit, amp, and possibly CD changer, what else does the EWD show is connected to the RADIO fuse? Also, where does the RADIO fuse draw its supply from on the EWD?

That is everything connected to that fuse.
Plus as the source of the power the EWD has the phrase "from power source system

 

[DaMan]

the two little connectors highlighted are showing positive on a connectivity test, with the battery disconnected and the fuses (ECU B1 and Radio) blown. Both the connectors are for little bulbs. One for the ash trey and one for the lighter.
Both the bulbs are blown (negative on a connectivity test when testing separately.

Should these connections be passing the connectivity test? The connection to the power outlet and the wires of the cigarette lighter don't pass. Which I think should be the case all around.

 

[DaMan]

And guess what, since I pulled this little bunch out the fuses are no longer blowing up if I connect the battery.
Of course, why wouldn't this fix the issue

Any amount of tugging, pulling, twisting of these wires is not causing a fuse to blow.

Electric goblins make me cry
I thought I was past weird electric issues after switching from my W202 Merc to this beautiful beast of Toyota engineering. I guess it's just me not the car I drive.

At this point how do I diagnose the real cause of the issue? everything is working as expected there is no issue to diagnose. Until there will be again.

 

[medtro]

Is that 2 cut wires and not taped in the middle?

 

[DaMan]

Is that 2 cut wires and not taped in the middle?

@medtro I wish it was that,
Those are the cigarette lighter wires I just cut the shrink wrap off to do the continuity test.
New heat shrink is on them now

 

[DaMan]

I have a theory I want to bounce around in this thread and see if it makes sense.
The two connections I talked about (pictured above) that are always live kinda make sense, now that I think about it. Those are tiny lights that are just always on. And if you open the cigarette lighter and it's dark you see the light otherwise no one notices. Keeping it always on just makes it simpler and for such a small thing over engineering doesn't make any sense.
So my theory is that I should try adding resistors in place of the blown lights and that should get all the circuitry to normal load. The only issue being my bulbs are blown and there is no reading on them about their wattage or resistance.

Question one, does this make any sense or am I getting a little too in my head with this?

Question two, can someone help me find the right resistors as a replacement for the bulbs?