Hybrid energy flow arrows

[NickySB]

Hi everyone

Since my engine change in late 2021/early 2022 I’ve has an odd issue of the energy flow arrows for the hybrid not showing. Everything else on it replicates - charging Battery, spinning wheels but the arrows have gone awol.

it’s been a bit of a ride since the engine was replaced with the 3rd or 4th hybrid Battery rebuild then the local garage blowing up the inverter some 6 months or so later during welding for the MOT, however not a Toyota/Lexus hybrid specialist nor the dealership themselves are familiar with this scenario or have been able to find the cause.
 

I wanted to document my attempts to resolve so far in case it helps someone else out when I (hopefully) get a fix. 
 

1) no apparent hybrid Battery wiring harness damage- there doesn’t appear to be any broken/pinched/visibly degraded wires and all fuses are good.

2) a lot of Prius owners loose their screen when the 12v Battery thermistor fails. I’ve tried changing mine, no change.

3) using TechStream I had codes B1498 - Communication Malfunction A/C inverter local & P3108 Lost Communication with AC system control module. After reading up I found during engine changes the AC compressor connector can get coolant in it and corrode. Checked the socket and it was corroded.  I had also recently had the system regassed at Lexus (after the engine change I’d left it empty ) and it held pressure but wouldn’t blow cold. I tried to clean the socket on the compressor up but when the plug went back on it went back on out of line and bent the pins, so I fitted a replacement compressor, B1498 is now historical but p3108 remains. I’ve not had it regassed to try the AC function yet. 

4) there’s nothing on TechStream when I go into the hybrid summary which shows any relevant degradation. 
 

5) I’ve checked the voltage and resistance on pin receptors 5 & 6 on the black plug which at attaches to the compressor and it’s within spec of the Lexus manual 

 

6) CAN BUS check on TechStream shows all units are white which means Currentlu Communicating on the CAN BUS.

the saga continues 

[hazelnut]

Hi Nicky,

I have a 2009 GS450h (working) and also a 2006 GS450h (not working).  I have managed to successfully clone a GS450h Hybrid ECU for my 2009, so I know enough about the CAN system to be dangerous, but maybe not helpful. 

ISTR that the Hybrid ECU has a dedicated CAN connection to the instrument cluster and infotainment system. I have sometimes seen the energy monitor 'glitch' like this while driving, and my assumption is that the CAN messages for this are low priority. Perhaps only sent out every second. My other guess is that other higher priority CAN messages are being sent instead. To figure this out conclusively you would need to attach a CAN BUS sniffer and then do some detective work to figure out which messages do what.  It may be that the hybrid ECU is constantly trying to get a response from something on the BUS that isn't responding (such as the AC?) 

-Hazel

PS I think the same BUS is used to the instrument cluster to show the kW display, so if that is not working that Bus may be broken.

PPS techstream talks on one of about 6 busses on the Hybrid ECU, so being able to talk to the hybrid ECU does not mean all its BUS's are good.

[NickySB]

Thanks that’s useful background. Yes the dash display for the Battery charging is also absent of arrows but does show the wheel & battery 

[NickySB]

A few more hours fault finding today using the guidance in the manual via Lex Tech. I checked the connector to the compressor again just to make sure I got the same. I can’t have checked properly before as I got different readings. The resistance was within spec ( under 1 ohm) but voltage was not, it should be under 1 v in the specified condition (power on, pin 5 to pin 6) but it reads 11.74v same as the Battery, so it looks like the cause is either the connector or the wiring harness. 

[NickySB]

Gone through the wiring diagram and looking at the circuit start to finish there doesn’t appear to be anything that drops the voltage so I’m not entirely clear why it should be testing below 1v, more investigation to follow 

[NickySB]

I’ve gone through the fault finding from start to finish , regardless of the flow chart, and other than having excess voltage as mentioned above between pin 5&6 on the compressor connector, the only other finding was poor ( over loaded) resistance reading between DOUT ( pin 3) on the connector & body ground.  
 

The flow chart points at the connector/harness for the excess voltage and the ECU for the resistance issue.

Initial thoughts are I’m still struggling to see how the voltage gets dropped from the circuitry so I’m inclined to focus on the ECU 

[NickySB]

On 9/1/2023 at 11:04 AM, NickySB said:

Thanks that’s useful background. Yes the dash display for the battery charging is also absent of arrows but does show the wheel & battery 

I should have clarified though that the kw gauge still works 

[hazelnut]

Hi Nicky,

Is the A/C control module not built into the A/C compressor?  I see you have tried replacing the A/C compressor, but I wonder if the harness is also corroded? I would be tempted to make a test lead that would allow you to easily plug in another known good compressor, from a friends car maybe? 

[NickySB]

Hi, yes you offer a good perspective and I think you’re probably right. I believe it is part of it ( but I’ll happily be corrected by those more in the know). I will try to conduct a test with another harness/compressor. Thanks 

[NickySB]

I realise I'm well overdue an update on this thread. Not been able to borrow a compressor as I don't know any other GS owners.  I've gone through the Lexus testing relating to this specific code (P3108-535). The guidance says DTC P3108-535 may be stored due to an open circuit in the SMRB circuit or SMRG circuit Voltage& resistance checks, but I checked the various voltages/resistances on 2 separate occasions and observed the following (under various power on or off scenarios as dictated by guidance):

• CLK port on motor connector to ground is good for voltage
• CLK port on motor connector to CLK on ECU connector is good for resistance
• CLK on ECU connector to ground is good for resistance

 

• ITE on ECU connector to ground is good for voltage
• ITE on ECU connector to DIM on motor connector is good for resistance
• TE on ECU connector to ground is good for resistance

 

• ETI on ECU connector to ground is good for voltage
• ETI on ECU connector to DOUT on motor connector is good for resistance
• ETI on ECU connector to ground is good for resistance

 

• DOUT on motor connector to ground is NOT GOOD for resistance
• DOUT on motor connector to ground has good voltage

 

• DIM on motor connector to ground has good voltage

The obvious suspect in that is the DOUT (3rd port from left) on motor connector, which would imply its a problem somewhere in the harness) however the guidance continues to point at hybrid ECU or hybrid ecu wiring harness ( i think that is P/N 82121-30D20). When the DOUT is checked, the ECU connector is in place and the power is off. As the ECU is connected at that point I can't rule it out. When ETI is measured from the hybrid ECU connector to DOUT for resistance, it is within spec.

[NickySB]

Finally managed to get the terminal pins out today. I was expecting to find corrosion or a snapped pin within but sadly nothing found - all connections were good and clean.

[NickySB]

Installed a fly lead from the connector back to the ecu pin, checked again but code still remaining. That would rule out the harness.