GS450h Engine crank fail - leading to check hybrid system er

zeczec · August 31, 2023

Good day folks! It me again, after a year's worth of fault-free driving, with an all-new problem with my GS450h 😏

I was about to leave for a wedding today and decided to take my car to the car wash first... but as I left my driveway, it moved off in electric mode, and then the engine fired up.... or at least it tried to! The 'crank' failed and it went straight back into pure electric mode, and the screen now read, check hybrid system error, check vsc, check ecb - the standard failed hybrid system stuff, along with check engine light on. I did an about turn and just about managed to bring it back into my driveway.

I disconnected the 12V Battery, and then pulled out the orange hybrid Battery fuse, and left these disconnected for about 5 minutes to clear the codes, and then try again. The same thing happened again. So I plugged in my laptop with techstream, and it yields the following 2 codes:

P0A4C-513 Generator Position Sensor Circuit Range/Performance
P0A4D-255 Generator Position Sensor Circuit Low

Any ideas what this could be? I took a lot of screenshots of techstream and can share them. I appreciate your help and time.

zeczec · September 1, 2023

Okay I had a scour around the internet and there seems to be a lot of advice to check the harness cable to make sure rats haven't eaten it or something. But we don't have a rodent problem where we live, but I decided to lift up my bonnet and see what I can find, and I was alarmed to find that part of the interior 'roofing' has been violated - not sure how! And it happens to be right above the big orange electrical cables. I have attached the pics.

So, the golden question is - could this be the culprit? Could a rupture in that black interior roofing lead to water ingress into the engine compartment - and if so, could that then cause a short circuit associated with the codes I'm getting? And if so yet, what would you advise? I've disconnected the 12V Battery and pulled out the orange hybrid Battery fuse.

I appreciate your help and time!

Linas.P · September 1, 2023

2 hours ago, zeczec said:

OMG!

Good chance that is your fault right there! Definitely the place where you start looking.

zeczec · September 2, 2023

Okay I've cleaned the area up and had a closer look, and I find that one of the tiny wires that forms part of the overall batch of wires (harness?) is cut. Pics attached! Very shocking. A long distant mechanic friend reckons it's definitely a rat/mouse job. Apparently that yellow padding stuff smells of cheese lol.

Do you reckon it's just a simple case of re-joining those 2 cut yellow wires with some crimping tool etc and duct tape? Or should I get this done by an authorised electrician seeing as we're dealing with the hybrid system of a powerful car?

Thoughts welcome.

zeczec · September 2, 2023

Apologies, I attached the wrong images to the previous post - now correct

Linas.P · September 2, 2023

I would get contact cleaner and a brush, clean all the wires and inspect them very carefully, even if they are not chewed trough completely, the insulation may be damaged to the point where they would short with each other.

So inspect them very carefully and insulate any cables that look damaged. As for broken wire I think it would be safe to assume just connecting it together and insulating it should be enough.

These wires in picture will be low voltage (less than 14.4V), so they don't require any special high voltage treatment.

I am not really expects on hybrids, but on normal car I would disconnect starter (the normal lead-acid 12V) Battery. Perhaps people who are more experienced on hybrids could advise if there is anything else to be disconnected when working on hybrid.

Herbie · September 2, 2023

Disconnect the 12V Battery (purely because I don't know what that yellow wire does), put some heat-shrink sleeving on one side and then either crimp or solder the wires together, finishing off by pulling the heat-shrink over the joint and shrinking it down.

All high voltage cables/harnesses are clad in orange so I doubt very much that you need to take any special precautions for this job.

EDIT: Forgot to mention that it's good practice to check the engine oil level every week; something which may have helped to sort this out sooner. Just sayin' like :thumbsup: