Gs450h Not starting error codes P0AC2, P0ADC and P0AE0

shinjuki · December 27, 2017

Hi All,

New to the Hybrid scene.

Short story is i bought a hybrid car that wasnt starting to begin with. Previous owner said the car was in storage for over 6 months so the HV Battery was reading less than 2v so the car wouldnt start.

Anyways. I took on the Challenge and pulled the HV Battery out and reconditioned them also replaced 3 modules as they weren't holding charge.

Problem when i hooked it all up. I got a p0ae6 error. So i pulled the Battery out and had a look at all the connectors and relays and reassembled it.

Now i am getting P0AC2, P0ADC and P0AE0. Looking at these codes from a Prius manual hoping its the same it says the car should still be able to get into ready mode? but obviously it doesn't =(

Attached is the logs/data i got from the Tech stream.

Any help or suggestions is welcome

Live DTC Printing(S821-02).pdf

SpeedyGee · December 28, 2017

22 hours ago, shinjuki said:

New to the Hybrid scene.

New to Hybrids but taken on a Hybrid issue, that's brave

I'm new to Hybrids myself, so I can't really advice you but as no one else had replied yet. I thought I'd ask if you slid the safety leave across as described by John below :-

shinjuki · December 28, 2017

Hi SpeedyGee,

Yes, it was brave of me. But i took a gamble as i picked up the car way under market price.

Plus it was a simple job removing a few modules and charging the rest upto spec.

Yes, locked the orange safety plug and the pushed it sideways to lock it in.

Britprius · December 28, 2017

The first code (PO517) relates to an open circuit temperature sensor on the Battery "probably a broken wire or poor connector"

POAC2 is open circuit Battery current sensor. This is a coil through which one of the Battery lead passes through that senses the current load on that lead. Again check for bad connections.

POADC/ POAEO are the main DC HV contactors and are supplied with 12 volts by the HV safety link contacts being made only when the link is in the full home position.

John.

shinjuki · December 28, 2017

57 minutes ago, Britprius said:

The first code (PO517) relates to an open circuit temperature sensor on the battery "probably a broken wire or poor connector"

POAC2 is open circuit battery current sensor. This is a coil through which one of the battery lead passes through that senses the current load on that lead. Again check for bad connections.

POADC/ POAEO are the main DC HV contactors and are supplied with 12 volts by the HV safety link contacts being made only when the link is in the full home position.

John.

Hi John,

P0157 is probably due to a new auxiliary Battery without a temp sensor so that should be fine.

P0AC2 is this the main HV Battery or the Auxiliary Battery? or could it be one of the Battery modules Battery connection that i may have not screwed on tight enough or too loose?

P0ADC/POAE0 i am thinking its either the relay is gone/fuse block in the HV Battery is dead hence why it is not giving the traction Battery any power. I tested the fuse inside the fuse block in the HV Battery it was good. But was unable to test the relays.

I have checked the HV safey link fuse and triple checked the safely link orange connector is in the home position fully slid across to the other side.

Britprius · December 28, 2017

1 hour ago, shinjuki said:

Hi John,

P0157 is probably due to a new auxiliary battery without a temp sensor so that should be fine.

P0AC2 is this the main HV battery or the Auxiliary battery? or could it be one of the battery modules battery connection that i may have not screwed on tight enough or too loose?

P0ADC/POAE0 i am thinking its either the relay is gone/fuse block in the HV battery is dead hence why it is not giving the traction battery any power. I tested the fuse inside the fuse block in the HV battery it was good. But was unable to test the relays.

I have checked the HV safey link fuse and triple checked the safely link orange connector is in the home position fully slid across to the other side.

POAC2 is the main HV Battery current sensor. This appears to be giving a reading of -200 amps, and since the HV contactors are not operating this reading cannot be true it should be zero.

The contactors can be checked by removing them and connecting a 12 volt supply across the the coil connections. There should be a loud click,and the other two connections should now be joined (zero ohms). If any critical code is still showing the contactors will not pull in to supply the high voltage to get to ready and start

Battery block (4) modules 7&8 locks low at only 14.2 volts where all the rest are around 15.6 volts. This will likely cause problems once you have the car running.

Have you cleared the codes? and do they all return?

The 12 volt Battery sensor can be gently prized out of the old Battery and simply glued or taped to the top of the new Battery.

John

shinjuki · December 29, 2017

14 hours ago, Britprius said:

POAC2 is the main HV battery current sensor. This appears to be giving a reading of -200 amps, and since the HV contactors are not operating this reading cannot be true it should be zero.

The contactors can be checked by removing them and connecting a 12 volt supply across the the coil connections. There should be a loud click,and the other two connections should now be joined (zero ohms). If any critical code is still showing the contactors will not pull in to supply the high voltage to get to ready and start

Battery block (4) modules 7&8 locks low at only 14.2 volts where all the rest are around 15.6 volts. This will likely cause problems once you have the car running.

Have you cleared the codes? and do they all return?

The 12 volt battery sensor can be gently prized out of the old battery and simply glued or taped to the top of the new battery.

John

Hi John,

P0AC2 does look odd. I cant see why it would read -200amps? Unless something shorted? Looking at the codes P0AC2 it isn't a critical code? Judging by a prius manual as i have no access to a Lexus one. I am assuming its similar?

I'll give the relays a play tomorrow. See how i go.

Yes, i did notice that. Must be one of the new modules that i didnt balance as it was reading decent volts. Might pull Battery out and charge this up.

I have reset the codes multiple times but they always come back.

I organised a tow in 3 days so if i don't figure it out, its off to my local mechanic that has the same car so he might be able to swap parts off his car to test.

shinjuki · January 2, 2018

On 12/29/2017 at 6:25 AM, Britprius said:

POAC2 is the main HV battery current sensor. This appears to be giving a reading of -200 amps, and since the HV contactors are not operating this reading cannot be true it should be zero.

The contactors can be checked by removing them and connecting a 12 volt supply across the the coil connections. There should be a loud click,and the other two connections should now be joined (zero ohms). If any critical code is still showing the contactors will not pull in to supply the high voltage to get to ready and start

Battery block (4) modules 7&8 locks low at only 14.2 volts where all the rest are around 15.6 volts. This will likely cause problems once you have the car running.

Have you cleared the codes? and do they all return?

The 12 volt battery sensor can be gently prized out of the old battery and simply glued or taped to the top of the new battery.

John

Had a quick look now that i've charged the weak batteries my volts are all good on the modules.

Also noticed i forgot to plug 1 set of wires in the fusebox relay inside the HV Battery. Hence those errors.

But i currently have a P0AE6 - 773 looks like its either the wiring or the dc invert-er inside the engine bay has died? Or is there an internal fuse inside it that i can check? looks like its screwed and glued on.

attached is the new log

Store DTC Printing(S821-05) (1).pdf

Britprius · January 2, 2018

3 hours ago, shinjuki said:

Had a quick look now that i've charged the weak batteries my volts are all good on the modules.

Also noticed i forgot to plug 1 set of wires in the fusebox relay inside the HV battery. Hence those errors.

But i currently have a P0AE6 - 773 looks like its either the wiring or the dc invert-er inside the engine bay has died? Or is there an internal fuse inside it that i can check? looks like its screwed and glued on.

attached is the new log

Store DTC Printing(S821-05) (1).pdf

There are three contactors (relays) inside the HV Battery.

One connects the negative supply the second connects the positive supply. The third relay is the precharge contactor.

The order of operation for the contactors is the negative and precharge contactors come in first supplying current to the inverter. The precharge contactor connects the supply through a resistor to stop high inrush currents from the Battery. After a second or so the positive contactor comes in missing out the resistor to allow full Battery current.

The fault code POAE2 suggests that the precharge contactor contacts are stuck closed "they sometimes weld themselves together".

You can check the contactor with your ohm meter to see that the contacts are open until 12 volts is applied across the coil. If the contacts show closed circuit at all times they are stuck. If this is the case you may be able to open the contactor and prize them apart to get you going, but it will need replacing.

John

shinjuki · January 4, 2018

On 1/3/2018 at 1:15 AM, Britprius said:

There are three contactors (relays) inside the HV battery.

One connects the negative supply the second connects the positive supply. The third relay is the precharge contactor.

The order of operation for the contactors is the negative and precharge contactors come in first supplying current to the inverter. The precharge contactor connects the supply through a resistor to stop high inrush currents from the battery. After a second or so the positive contactor comes in missing out the resistor to allow full battery current.

The fault code POAE2 suggests that the precharge contactor contacts are stuck closed "they sometimes weld themselves together".

You can check the contactor with your ohm meter to see that the contacts are open until 12 volts is applied across the coil. If the contacts show closed circuit at all times they are stuck. If this is the case you may be able to open the contactor and prize them apart to get you going, but it will need replacing.

John

Hi John,

When i removed the junction box there were only 2 relays? Both clicked and seemed fine. Do you know where the 3rd one is?

Britprius · January 4, 2018

3 hours ago, shinjuki said:

Hi John,

When i removed the junction box there were only 2 relays? Both clicked and seemed fine. Do you know where the 3rd one is?

Unfortunately I cannot help with the exact location. It may be built in to one of the other relays. On other Toyota/Lexus systems I have dealt with it is a separate relay, but the only information I have that shows this relay shows it as a solid state "transistor" relay. Although this type of relay has no moving contacts the switching transistor can go short circuit. See the block diagram of the circuit below. The relay you are interested in on the diagram is below the words "Hybrid vehicle converter" This is the SMRP relay

You will see that when the transistor conducts it passes Battery current through a resistor to the boost converter. When relay SMRG contacts close all the current goes through those contacts as they short circuit relay SMRP

I hope this is of help.

John

SpeedyGee · January 4, 2018

5 hours ago, Britprius said:

It may be built in to one of the other relays. On other Toyota/Lexus systems I have dealt with it is a separate relay, but the only information I have that shows this relay shows it as a solid state "transistor" relay.

That's a bit different from the Prius then isn't it ? On that, I gather that the pre-charge contactor, and pre-charge resistor as well as the negative and positive contactor all sit on the hybrid Battery junction block. Is that correct John ?

Britprius · January 4, 2018

1 minute ago, SpeedyGee said:

That's a bit different from the Prius then isn't it ? On that, I gather that the pre-charge contactor, and pre-charge resistor as well as the negative and positive contactor all sit on the hybrid battery junction block. Is that correct John ?

That is correct. I also have a Block from an RX450H that also has three normal HV DC contactors. The block diagram shows three contactors, and the only other information for position is below.

John.

Britprius · January 4, 2018

The relay does exist, but as I said previously it is a solid state relay. It does not make sense for it to be any distance away from the other two relays, and may even be integrated. This would show as possibly up to three extra contacts on one of the other two relays.

John

SpeedyGee · January 4, 2018

Indeed, no reason for it not to be part of the junction box. As you say John, could well be built in to it.

shinjuki · January 8, 2018

both the relays only had 4 pins so cant be those relays in the junction box.

I did open up the junction box and reassemble it. It consist of thick metal connectors/joiners maybe a pin fell out? or something got loose? mmmm

shinjuki · February 1, 2018

Update: So it was the Dc-Dc converter that was the problem.

The car turns over now but shakes violently and then stalls. Seems like doing this a few times has drained the HV Battery. Also seems like i have a few more dead cells to replace.

Anyone know why it will turn over and stall? The first time it was on for a good 10 sec shaking. We checked the fuel pump and 1 of the spark and could see spark to the engine and fuel.

shinjuki · February 2, 2018

Update: got a new hybrid Battery from a 2010 gs450h

Part number slightly different but everything looks identical. Plugged it all in now im getting fail to start engine code as it seems like the mg1 is trying to start the engine but it cant.

before playing anymore we decided to stop as we didnt want to drain a good hv Battery.

SpeedyGee · February 2, 2018

Any errors codes from Engine PCM ?

There must be a documented procedure to follow for diagnosing a non starting engine on these Hybrids. Would be good to see what that is.

ColinBarber · February 2, 2018

might be worth paying for an hour or two for access to the workshop manual:

https://www.lexus-tech.eu

shinjuki · February 3, 2018

from memory it was p3191

SpeedyGee · February 3, 2018

Have you checked the health of your 12v Battery ?

That needs to be in good condition for the car to start too.

Maybe worth giving that a good trickle charge and trying again.

shinjuki · February 4, 2018

Yeah, was a fully charged one... =(

SpeedyGee · February 4, 2018

You say "was".... so it still fully charged currently?

Probably worth monitoring voltage level as you try to start the car.

Other thoughts are, that you confirmed fuel is present, a spark is being generated, next up would be to confirm timing.

SpeedyGee · February 4, 2018

Some more thoughts, just googling about for info on P3191, the code itself seems to be thrown when the engine fails to start and it can fail to start for any reason a normal engine fails to start but most are suggesting you should check/clean the throttle body and MAF sensor.

The theory being, that a dirty throttle body/MAF leads to not being able to control the air flow at idle.