Hybrid Battery Negative Contactor

[Jenf52]

Hi

 

Anyone had this code before and any idea to the solution - 2007 RX400h

Toyota garage no help. Car will not start - so cannot take it anywhere

[PCM]

https://www.autocodes.com/p0aa4.html 

AA/Green flag ?

[Mihanicos]

To pinpoint the problem and decide which remedial action you should follow, you need a scan tool, preferably the Techstream.

There is a number of sub codes, each referring to a different circuit malfuncton with specific procedures to find the fault and subsequently repair it.

If you have P0AA4-242 the car will not run. First thing to check is the freeze frame data which will guide you to the problem.

If you intend to carry out any inspection or work on the car's high voltage systems/circuits, you must observe all safety rules and codes of practice relating thereto. Before any inspection or work is done, you must wait at least 10 minutes after you have removed the service plug to give time to the capacitors within the inverter with the converter assembly to discharge.

There are a few learned members of very high ranking who hopefully will help out.

Kindest regards,

Chris.

[steve2006]

Hi Jenny and welcome to the LOC

Apparently quite a common problem on Toyota/Lexus hybrids, due to suspect quality and high currents the contacts within the  contactor (a form of electrical relay) can stick resulting in the fault code you now have.

Sometimes a physical tap on the contactor can release the contacts but this may only result in a temporary solution as they are likely to stick again.

Unfortunately only the complete unit is available as a replacement and given the dangers of working with HV electrics a DIY approach to repair is not recommended unless you are competent to carry out such work and have the required PPE.

Further professional diagnosis is also recommended to confirm the fault is the contactor unit given the price!

You don’t provide your location, there are several specialists within the UK but maybe not in your country?

https://diag.net/msg/m5yo52ugtu9jod7l4pxa0dsdyp

 https://share.qclt.com/丰田普瑞斯原厂英文手册pdf格式/repair manual/04pruisr/05/21bpm/0aa4228.pdf

[Jenf52]

Is this  the black box unit  ( or part of )situated underneath the back seats with the batteries

[Spacewagon52]

Sorry Jenny not sure what you mean?

Do you mean the main hybrid Battery?

 

A Photo would be useful.

[Herbie]

What problems are you having and what LED you to this negative contactor?

What OBD2 codes have been generated?

[Jenf52]

1 hour ago, Herbie said:

What problems are you having and what led you to this negative contactor?

What OBD2 codes have been generated?

Code POAA4 Hybrid Battery Negative Contractor Circuit Stuck Closed

[Herbie]

2 hours ago, Jenf52 said:

Code POAA4 Hybrid Battery Negative Contractor Circuit Stuck Closed

 

4 hours ago, Jenf52 said:

Is this  the black box unit  ( or part of )situated underneath the back seats with the batteries

It could be. As David said, a photo would help us to see what you're seeing but yes, it looks likely.

The contactor is part of the HV Relay Assembly:

[Mihanicos]

If you can access the contactor it may be possible to replace it by another used from another unit.

You can also replace it by another of the same or higher rating available in the electrical market.

This involves removing the faulty contactor and completing the circuit to a replacement contactor placed in a suitable box close by.

You should be able to find everything you need in England.

Chris.

[Herbie]

6 hours ago, Jenf52 said:

Is this  the black box unit  ( or part of )situated underneath the back seats with the batteries

Rather than editing my previous post I decided to add this one in because, unless you've removed the back seats completely, and then removed the Battery cover by first removing 28 bolts and 6 nuts, whatever you're looking at is not the HV Relay Assembly. Here's the removal procedure:

[steve2006]

There were 2 posts on this problem as a new one was started, I have merged them so they make more sense.

Jenny it would help us to help you if you provided your location in the world 😀

[Herbie]

Any progress on this yet Jenny?

[Spacewagon52]

Is this procedure potentially dangerous? If you don’t know what you are doing?

[Herbie]

2 hours ago, Spacewagon52 said:

Is this procedure potentially dangerous? If you don’t know what you are doing?

If you don't know what you're doing, yes, it is - but I would hope that people know their own limits and if they don't have the correct protective gear, or if they aren't comfortable working with the sorts of voltages that can be found in there, then they would have the sense to take it to someone who does.