Mod Details

PremiumYes Difficulty Mod ID1769 Creditevilution/Askold For Linkhttps://www.evilution.co.uk/mod/451-ed-inverter-removal.htm Copy to Clipboard

Every 10 months or so, my 451 ED would suddenly lose power and show “Drive Sys Eng Off”.

Even though it would restart immediately after turning the ignition off and on again, you had to come to a complete stop in order to restart the car. Somewhat scary if you were driving on the motorway. 3 times I lost power and had to coast with no power to a place of safety to quickly put the car in neutral, turn it off, restart, select drive and pull away. There was rarely a good place to do this.

Turns out that it was a component slowly failing in the DC/AC inverter but it was so rare, the fault wasn’t worth chasing.

However

One night, late in 2022, I got in my 9 year old 451 ED and turned the key to start it in order to drive to work.

Despite the car being in park and the handbrake on, the car lurched backwards an inch and all the error lights came on the dash. I tried removing and reinstalling the HV disconnect plug with no joy. That’s when I could smell burning egg and the car wouldn’t do anything. I removed the disconnect plug again, pushed it away from the house and went to work in another car.

In the coming months, I removed the HV battery, checked the cells and replaced the mega fuse. However, none of this helped. The car was still dead and wouldn’t work. I was literally 12 hours from giving up. As nothing worked, I was going to come out the next day and strip the car for parts.

As luck would have it, I spoke to Askold from GoSmart who told me that he was sure it was a failed DC to AC inverter. Fast forward a few months and I can confirm that he was correct. It has suffered a catastrophic high voltage failure.

However, getting to the point where the car worked again was a long and potentially expensive story.

I always recommend checking for the cost of new parts directly from smart before looking for 2nd hand as many items sell new for less than piss-take merchants who sell 2nd hand parts. On this occasion I was wrong. Smart wanted £4815 for a new inverter. That’s 2/3rds the cost of the car so again, I considered scrapping the car.

I looked around for 2nd hand ones but there were none for sale at the time. Thankfully Askold came to the rescue for the 2nd time out of 3 occasions with this fault. He had one I could buy and it was a much better price, closer to 1/8th the cost which I was happy to pay. About 3 weeks later it arrived and I spent a day removing the old one and fitting the replacement.

Important

Disconnect the 12v battery. Remove the HV service plug. You will also be disconnecting the AC lines from the AC compressor so if your AC works, disconnecting the pipes will discharge the AC gas at very high speed. Ideally you should get the AC system emptied by a professional.

Removal

It’s not hard, just a bit tricky and you’ll need 1 tool that you probably don’t have (I didn’t which is unusual for me).

Open the engine cover. The module highlighted red below is the 400v DC to AC inverter.

On the top left of the inverter is a black electrical connector. Pull the slider back from under the plug to disconnect it.

Look down the inverter edge nearest you and you’ll see an E12 bolt to remove. This is an earth connection.

Next to that is a black cap, pull it off…

…to reveal a 13mm nut. Remove this. This cable goes to the 12v battery positive. This inverter connection turns the 400DC from the HV battery into a 14v DC output to charge the LV battery.

There are 2 water pipes going to the inverter, obviously for cooling the unit. Use a pair of pliers and squeeze the hose clamp to open it up. At the same time pull the pipe off. Oh, by the way, about 5 litres of coolant will now slowly drain from the car… unless you clamp the pipes. If you do clamp the pipes, you’ll not lose much coolant. Just the coolant that’s in the inverter.

Over to the left is the air conditioning compressor. Using a Torx45 bit, disconnect the pipe. If you didn’t have the AC drained properly, expect a surprise as the pipe pops off and the gas escapes very quickly.

Follow the pipe to the right and you’ll find a plastic clamp.

Unclip it to release the AC hard pipe. Move the hose out of the way.

Below that is the other AC hard line. Remove the 10mm nut and…

…disconnect the pipe.

Look further right to the top HV power connector.

Press in both side clips and pull the connector out.