Rx400H Awd Rear Diff Problem - Help / Advise Please

[ramsascooby]

Hi,

I'm posting on here as there are far more rx400h's in the U.S.A and you may be able to oofer help and/or advise I can'r seem to get in the U.K.

I have a 2006 rx400h, with has covered 120,000 miles without a hitch until 2 weeks ago.

I got the check hybrid system light come on.

I had this checked by a recovery service ( the A.A) and the fault code was - Drive Motor "B" position sensor circuit - POA 45.

This was message cleared by therecovery service guy, the car was o.k for approximately 50miles then the same

Check Hybrid system indication came back on along with check vsc system and check awd system.

The car drove normally and was charging and using the battery as per normal.

I took it to my nearest lexus dealer and the checked the fault log and got the same fault code - Drive Motor "B" position sensor circuit - POA 45.

They have told me that they have checked the circuit connections and all is o.k, but if it comes on again I will need the rear Differential replacing!!

Their diagnosis seems rather dramatic and very expensive £2300 ( $3500).

My questions are

1

[ramsascooby]

1 - is their diagnosis reasonable?

doesn't seem very technically based to change out a full unit

2 - can an awd car be converted to be a fwd only vehicle?, lexus U.K don't sell the fwd variant.

the physical, I would Imagine would be disconnecting the power and monitoring to the rear diff, what would be required to convince the management system that the rear drive doesn't exist?

[lenore]

First has the recall been performed on the inverter? It is possible you have an inverter failure and there was a recall and repair on the inverter in the Unitied States on your particular year RX. You could go to MYLEXUS.com and enter your vin # and see if possibly it comes up with that recall info. As for your other questions I dont know...Was there any other codes other than the one POA45?

[ramsascooby]

Hi

The inverter recall has been done.

The hybrid system seems to operate perfectly well with regard to charging and utilising the battery, also the cars power feels the same..

Both times the fault has come on is after driving and then restarting after a short period turned off.

It hasn't come on whilst driving.

[maseace]

I found the diagnostic instructions for this fault code.

P0A45 Diagnostics.pdf

[lenore]

You know after looking at that pdf file, I would be tempted to reseat the rear plug on the rear motor/transmission assembly. It could very well have some corrosion. I don't know what safety procedures you would have to be aware of first, but I do know that 400 volts dc is a lot of juice. Be very careful.

[Rx8]

Hi Ramsascooby,

I today bought a Lexus Rx400h 2008 model and after driving back when I bought a after doing 250 miles it suddenly showed the code when I was driving on the highway the fault code check Hybrid system with Vsc and Check AWd. 

So I checked It is POA45 with OBD and cleared it too after that it has not come back as yet after doing 100 miles .

the car drives all fine , I'm worried now what could be the problem  , please help!!!

[Rx8]

Hi Ramsascooby,

I today bought a Lexus Rx400h 2008 model and after driving back when I bought last night , after doing 250 miles it suddenly showed the code when I was driving on the highway the fault code check Hybrid system with Vsc and Check AWd. 

So I checked It is POA45 with OBD and cleared it too after that it has not come back as yet after doing 100 miles .

When I Start the engine it gives constant humming noise tone for about 30 seconds and then stops , which I believe is coming from the back of the car 

the car drives all fine , I'm worried now what could be the problem  , please help!!!

 

 

[welland]

Hi Ramascooby,

Are you in the UK?  Me too?

I have just got the same problem with my 2006 RX400H.  Did you resolve yours?

[ramsascooby]

Hi

 

yes, in the uk.

used to reset it 1 or 2 times a month.

Lexus wanted to replace complete unit as only the japanese are clever eniugh to mend it!!

 

resolved it completely by trading in on a newer rx400h.

i know thats not much help

 

andrew