MG4 - Post crash repairs query - Pyro-fuse

[RoadTest]

First off, a thank-you to the many posters here on the forum - and most particularly to the gentleman who shares the workshop guides on his website. These have all been invaluable.

Background: Own an MG4 as daily driver - works well no complaints. I recently crashed the car at high speed. Airbags deployed, HV battery cut-off engaged. I am now in a position where I must repair the vehicle, performing most works myself.

Spoiler: Car crash image

Note: There are many codes to investigate and clear. I'm still waiting on a more fully-featured scanning tool update to make mine compatible with the MG 4.

Question 1 & 2: Does the MG4 have a pyro fuse & where is it located? There has been conflicting information here on the forum and I do not have a strong sense either way.

Observation 1: The "General Workshop Procedures" manual does at no point mention a pyro-fuse. It does however mention, on page 973, mention a "High-Voltage Power Distribution Unit Fuse" within the Power Distribution Unit (PDU) held in by 6 screws.
I believe the HV-PDU fuse to be this cluster of 3 fuses, rated at DC 500V, 60A (Please see below image). I initially had some confusion as the manual referred to a single fuse. These fuses still have continuity.

Spoiler: Suspected HV PDU fuse

Observation 2: The only other fuse of significant note mentioned is in the Energy Storage System (ESS), which appears to be a way of referring to the Battery Management System (BMS) and the physical battery itself. According to the EH32 Service Circuit Diagrams, there appears to be a 500A, J-Case style fuse (see screenshot below). Being a J-Case style fuse, this is unlikely also to be the pyro-fuse, correct?

Spoiler: ESS circuit diagram screenshot

I am keen for other posters to share their thoughts and observations. I'm happy to document the process as I go about repairing the vehicle.
So far, I must: Reflash the SRS-Airbag computer, replace safety devices (airbags, seatbelts and crash sensors), address / clear codes and potentially rectify the pyro-fuse situation.
And after that, physical works including steering and suspension repairs.
Finally, pay increasingly larger sums of money to the panel-works professionals.

 

[siteguru]

Is the pyro fuse not normally located underneath the car? In the MG4 it may even be part of the battery pack assembly, so accessible underneath the car behind a panel.

A read of this thread may be helpful:

Post in thread 'MG 4/Mulan after crash. Drive with deployed airbags. Crash reset. Cable and Software.'

Apr 2, 2024

Progress till now.
All 4 seatbelts are fixed as standard no pyro safe belts. Front airbags are unmounted. All 6 blown pyro are replaced with resistance 2.2ohm to test srs module when is fixed.
Front radar is fixed temporary.
Front gaps are fixed. Bumper and hood need some more filler and correct paint.

• chiMol

• 

Furthermore, ChatGPT gave me this response ...

Where is the pyro fuse located? Reply in English please

ChatGPT said:​

The pyro fuse in the MG4 EV is part of the High Voltage (HV) Power Distribution Unit (PDU). To access and remove the PDU fuse—which includes the pyro fuse—you need to:

1. Turn off the start switch and wait more than 5 minutes.
2. Remove the manual service disconnect.
3. Remove the rear seat cushion.
4. Detach 12 bolts to remove the rear floor subassembly.
5. Remove 8 bolts to open the upper cover of the HV PDU.
6. Remove 6 screws fixing the PDU fuse to the unit.

This indicates that the pyro fuse is physically located within the HV Power Distribution Unit, which is situated above the HV battery pack and under the rear floor section of the vehicle.

 

[salty]

To the forum. Glad your ok, after the accident. And good luck with the repairs.

 

[kozd]

Mg4 havent got a pyro fuse that deploys after aciddent. The fuses you mention wont gonna deploy in a crash. You need to clear crash data at airbag module with diagnostic tools and hourly paid diagnostic software by saic. There was a trick to drive the car i cant remember it was something like disconnecting and connecting airbag module and after connecting you fasty get car to drive and it can drive like that after locking it you need to do it again.

 

[T1 Terry]

Under the centre console there is crash module, unplug that and it all comes good. There are people who can reflash these modules rather than pay out the big $$ for a genuine replacement.
This bloke has used a different model front wheel drive MG EV to repower his 928 Porche, but I believe the module placement under the centre consul is similar in the MG4 https://www.youtube.com/results?search_query=928+v8+ev+eposode+1 ..... you might need to play them at 2x speed to get to the bits you need, but over all .... if you have trouble sleeping, this might help

T1 Terry