Margate330

I would like to make a new thread just for the Power Steering Converter.
This thread will be for diagnosis, troubleshooting, and continued research.

Power Steering Converter aka DC/DC converter: this unit takes the high voltage from the hybrid battery and steps it down to 42V for the Power Steering. A 12V enable signal from the Power Steering Ecu is required for this unit to turn on(see below).


(Posted in fair use for commentary and discussion).



Here's what I have so far on the Power Steering Converter.
>> If any errors, please let me know do I can fix.



There are two wires on the Power Steering Converter that are still unknown.
P46, pin 1(red/rellow): ?
P46, pin3(red/white): ?
>> If anyone knows what these do, please post.

asampson

Red and yellow wires and red and white wires are the power steering converter malfunction signal wires

asampson

I have literally got to a dead end have checked all of the wires resistance and voltage the only thing that I can’t work out is why the 12v on the yellow and black wire (DRDD p41-11) is not being pushed down to the converter to signal it to send the 42v back.

asampson

I have circled something called EC2 on the picture I don’t no if this is a fuse ??? And this could be the problem if it is

Margate330

This just made things easier.

Margate330

EC2 refers to a harness junction.
This would not be suspect for a rim curbing.

Refresh: ok, so you say you can inhibit the DC/DC converter to make 42V by applying +12V to the inhibit signal wire(P46, pin2, yellow/black) ?

asampson

No sorry this someone has made another thread for me with dc dc converter issue the curbing was not my vehicle.
however I have gained a reading of 42v by adding a 12v battery cable down the p41-11 lead which is the I’m guessing signal lead to the power steering converter which turns into the p42-2 pin.
thanks for your input as like I said at dead end

asampson

Just to recap bought a 2006 rx400 h 2 weeks ago.
plugged in power steering fault c1568 present and will not clear.
have followed other thread and also my own research into the wiring.
have checked all resistance and voltage no faults or breaks.
however when car is turned on 42v does not appear unless I manually do the 12v on the p41-11.
have changed ecu and converter but with same exact results.

Margate330

Friend, you are not at a dead end, I think you are very close to solving this.
Ok, P41-11 is the wire from the perspective of the Power Steering Ecu and it looks like you can enable the DC/DC converter to make 42V, GOOD!

Next: from your diagram posted above, only two wires in question left was the signal error wires from the DC/DC converter so I will ignore these for now until we know more about them.

Next: I think we need to know for sure and prove that the Power Steering Ecu is alive and not brain dead. If you have Techstream, can you verify you can connect to this module? It should show up because it's on the Can Bus. If not, can you think of a way to prove the Power Steering Ecu is doing something?

Next: clear all codes with a batter unhook and let us know what codes pop up please.

asampson

I think your your right I no I’m close but can’t work out why it would not be sending that 12v.
I don’t have tech stream I have a launch x431 pro and can access a data feed which confirms that the DRDD P41-11 is only feeding the converter 0.4v not 12v. Also when car is on I have checked voltage on the signal leads and it has a voltage reading so can high and can low must be working . However the live feed must be showing that the ECU Is reading and working.

also sorry what is a batt unhook will do that and send codes

asampson

Also I have looked at the wiring and this is where the 12v signal come from and I have checked the mpx-b1 fuse and all is ok.

from this Lexus troubleshoot it states if I get a reading of these pins which I do 12.1v to change ECU I have lol. Honestly round in circles

here is a link if anyone wants to do there own diagnoses
http://manualespurdy.cisdigital.com/Lexus/RX400h/rm03g0u/MANUAL.HTM/rm03g0u/ewd/index.html

Margate330

If your Launch scanner is seeing 0.4V on the DC/DC converter inhibit wire and that agrees with your measured voltage done manually, it looks like you proved the Power Steering Ecu has brain activity.

Yes, a battery unhook & reconnect to flush all codes current and pending and see what pops up please, what I like to call a "hard reset" like on my computer. lol

Margate330

That flow chart is confusing.
P41-6 & P41-5 are just the input power supply wires for the Power Steering Ecu.
It's just making sure you have +12V to power it. lol

asampson

I have this diagram . p41-5 looks like it is a black ground wire.

Margate330

Yes sir, you are correct, it goes to battery/frame ground

It seems like the junk yards are selling bad parts from wrecked cars.
To rule out the DC/DC converter, voltage injection can be done by leaving the DC/DC converter unplugged and injecting 48V directly into the Power Steering Ecu, if I understand correctly.

If your steering starts working, you got another bad Power Steering Converter aka DC/DC converter.
*note- requires a safe way to supply +48V

However, if after voltage injecting +48v with the DC/DC converter unplugged and you are still throwing the code and have no steering, you may have another bad Power Steering Ecu or something connected to it

>> Please see post #30(how to) & #31(warning) here: https://www.clublexus.com/forums/rx-...d-c1241-2.html