ATH10 hybrid electrical puzzle!

[Clivus]

Dear Friends

I am an ex-pat who owns and maintains a 2008 Hybrid E-Four in Perth Western Australia.

Recently, the engine started to falter whilst driving, making the car jerk. This quickly got worse and although the engine will start, the car can no longer be driven.

I have eliminated fuel starvation as an issue by replacing the fuel pump and filter. I also cleaned the throttle body. No improvement!

No fault codes have shown up on the OBD scan!

Some strange electrical faults have appeared with accessories so I have looked at both the main and aux. batteries. The main battery was replaced in 2024 and seems fine. The aux. was down to 11.6v and 13.6v with engine running. So I have replaced it. Now it's 12.6v, but still only 13.6v with the engine running, not 14.6v which I believe it should be.

So my question is can the alternator be the root cause of this puzzle?

Your opinions are welcome, because owners of imported Toyotas seem to be very unpopular in Perth and all I can do is read a multimeter.

Clivus

 

[Rojie]

9 hours ago, Clivus said:

Dear Friends

I am an ex-pat who owns and maintains a 2008 Hybrid E-Four in Perth Western Australia.

Recently, the engine started to falter whilst driving, making the car jerk. This quickly got worse and although the engine will start, the car can no longer be driven.

I have eliminated fuel starvation as an issue by replacing the fuel pump and filter. I also cleaned the throttle body. No improvement!

No fault codes have shown up on the OBD scan!

Some strange electrical faults have appeared with accessories so I have looked at both the main and aux. batteries. The main battery was replaced in 2024 and seems fine. The aux. was down to 11.6v and 13.6v with engine running. So I have replaced it. Now it's 12.6v, but still only 13.6v with the engine running, not 14.6v which I believe it should be.

So my question is can the alternator be the root cause of this puzzle?

Your opinions are welcome, because owners of imported Toyotas seem to be very unpopular in Perth and all I can do is read a multimeter.

Clivus

 

 

Hello Clive,

 

Welcome to the Forum.

[Jeza]

Hi

There is no alternator on the hybrid, the aux battery is charged from the inverter / converter, 13.6v seems reasonable if the aux battery is fully charged.

You have replaced the aux battery so the terminals should be good, check the earth straps, battery to body and body to engine. Anything wrong with the hybrid system would throw up codes. Could be the engine ECU, clutching at straws now without codes. 

[smurf]

There is no alternator on the hybrid. There is a DC-DC converter that (on my 2003 hybrid) outputs 13.9V when the ignition is on, with the supply coming from the hybrid battery. 13.6V should be absolutely fine to keep everything powered up, but it could be a indicator of gremlins at play. 

 

Is your OBD scanner compatible with JOBD? Even if it is, it might be worth getting techstream and a minivci cable as you could check live data and see what is going on. It also might pick up codes that a generic reader has missed. 

[Clivus]

Thanks to Jeza and Smurf for your replies. I agree my alternator terminology was wrong. And I don't think that is where the fault lies since the car starts normally and is charging.

But the motor idle speed is erratic and the car will not drive properly.

So maybe it's the main battery voltage regulator? Anyway, I'm still searching for an experience hybrid electrician who is willing to make house calls. 

Clivus

[smurf]

Have you checked the usual petrol engine problem causers? A dirty throttle body seems to be a bit of a feature of Toyota's and can give the problems you have, MAF sensors also get dirty and cause running issues, there could be ignition problems such as spark plugs or coil packs.

[Clivus]

Thanks Smurf. Throttle body & MAF eliminated. Looking at coils tomorrow.

[PaulE]

Hi, just a bit confused with Jeza and Smurf saying there is no alternator on the Hybrid (series 1?) as I am sure I have one and I have a diagram below saying "alternator" unless it is not a conventional piece of kit. Is this the DC to DC converter?

 

[smurf]

An alternator is another name for an AC generator. When applied to cars, what most people are talking about is the small generator ultimately responsible for providing the 12V required to charge the battery and power the 12V systems.

 

The Alphard hybrid does have an alternator, but it is not powering the 12V system. It is actually a starter/generator that is used to start the engine under certain conditions, and I believe it acts as a generator when needed to help charge the hybrid battery at tickover. 

Edited Wednesday at 07:56 PM by smurf