My Lexus nx300 h after an accident damaging only side door ( front and back completely untouched ) is not starting it just starts the engine and than shuts off
it searched it’s due to pyro fuse .
can some plz help me to locate this fuse ? And how to replace it as its a mechanical switch .
google does notgive me any thing on this hence posting here with knowledgeable and experienced sources.
regards and many thanks for reading and reply
Mt Dan Garry

 

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Dear
the pics you showed are for disconnecting 12v battery and HV battery ? correct ..and what about the location of pyro fuse , if you can help to share your contact number i can text you or call you if you dnt mind.

cheers

 

I have combed through dozen of pages of wiring diagrams from powertrain management, power distribution, hybrid system circuit, passive & supplemental restraints, and there is no mention of a PYRO fuse anywhere.

I also checked N. America/Canada, Europe, Latin America and Australia lexus emergency response guides, and none indicate that a PYRO fuse even exists.

Have you scaned your vehicle OBD system?

Check and clean the battery cables; make sure it's super tight.

Make sure your battery voltage is ≥ 12.4 volts.

Let me study the diagrams and hopefully I can point you toward the right direction.

 

There are only 3 emergency shut-off devices are in the attached.

 

Thanks bro for detailed response and yes it was scanned and points toward fuel pump but fuel pump never had an issue it’s just after accident it wouldn’t start(due to cut of switch /pyro fuse ) it’s starts but turns off after couple of seconds .
12v battery is good even I have jump start attached as well just in case .

please see below image at end form Lexus manual




QUOTE=tammap;11836157]I have combed through dozen of pages of wiring diagrams from powertrain management, power distribution, hybrid system circuit, passive & supplemental restraints, and there is no mention of a PYRO fuse anywhere.

I also checked N. America/Canada, Europe, Latin America and Australia lexus emergency response guides, and none indicate that a PYRO fuse even exists.

Have you scaned your vehicle OBD system?

Check and clean the battery cables; make sure it's super tight.

Make sure your battery voltage is ≥ 12.4 volts.

Let me study the diagrams and hopefully I can point you toward the right direction.[/QUOTE]

 

The owner's manual doesn't explain the fuel pump and high voltage current shut-off in detail. At certain level of impact, it causes airbags to deploy and then the vehicle computer will shut-off high voltage current and fuel pump based on impact airbag sensors on the front, sides and rear of the vehicle.

There is no PYRO fuse nor mechanical kill switch that the consumers can turn on/off.

Did any of your airbags deploy?

Was there any damage to the LF fender and/or LF pumper?

What was the fault codes that point toward the fuel pump?

 

HI Bro

below are images of the demage for youre reference .
No the airbags were not opened.

 

Add at least 1/4 of a tank of fuel to the vehicle. Try to start the vehicle again.

You will need Techstream or an advanced OBDII scanner to read the subcode for P0A0F.

Can the vehicle enter the READY-on state? If not, the HV battery needs to be charged before any diagnosis can be proceeded.

You'll need one of these to charge the HV battery.

https://www.midtronics.com/ev-solutions/grx-5100/

That will allow you to diagnose for fault code P1390. Best of luck!

 

The pyrotechnic disconnect ("pyro fuse") device is located within the NX high voltage battery assembly, which is under the rear seat. There is probably a way to replace it without complete removal and disassembly of the battery assembly, but Toyota/Lexus does not appear to disclose it. Their legal staff may be concerned about liability claims in the event a customer is injured or electrocuted while attempting a repair. The attached drawing was copied from a RAV4/NX hybrid drive technician training manual published by Toyota.

Interestingly, Tesla seems not to have a similar concern. Their pyro fuse devices are in an accessible location and replacements are even sold by Amazon here in the USA:

 

Toyota/Lexus calls it a High Voltage fuse. This is the first time I've heard it referred to as a Pyro fuse. I learned something today.

 

This type of emergency disconnect is common in hybrid and electric vehicles. In case of a crash event, the "fuse" must be fast enough to disconnect the high voltage battery before some metal shard pierces the insulation of a high voltage conductor, which could render the entire chassis "live", potentially endangering first responders. Conventional fuses are relatively slow thermal devices that rely on an over-current condition to melt the fusing element. In the hypothetical scenario I described, no over-current would occur. Pyro fuse devices have a detonator that is similar to what is used to inflate the air bags. The pyro fuse detonator, when triggered by the air bag control module, creates a controlled explosion that obliterates a metal link in a few thousandths of a second, which is 10 to 1000 times faster than a thermal fuse. While a conventional fuse is a 2-terminal device, a pyro fuse has 3 or 4 terminals, with the additional terminals used only to trigger the explosion.

 

For North America/Canada Toyota and Lexus vehicles, the High Voltage fuse is built-in the service disconnect.