GS450H WONT START

[SIMMO91]

HELP!!!  My gs450h has lost all power to the instrument dashboard / radio won't turn on nothing working except the lights, horn,  hazard lights... doors unlock and lock ok using the keyfob but press start button nothing happens, also the streeing wheel is locked in position so can't release the streeing.  I have checked the 12v Battery in the boot but its OK reading 12.7v states good on the meter. I have disconnected the earth lead for 10mins and reconnected but still no dash lights. I have also checked every fuse in all locations and not one is bad and 12v is going from Battery to the engine fuse box... anyone know whats happening?

[Spock66]

15 minutes ago, SIMMO91 said:

I have checked the 12v battery in the boot but its OK reading 12.7v states good on the meter.

A simple voltage reading is not sufficient confirmation that the Battery is ok, do you have a charger or booster pack you can try.

[SIMMO91]

Hi yes have have put a fully charged booster pack on made no difference at all.

[SIMMO91]

34 minutes ago, Spock66 said:

A simple voltage reading is not sufficient confirmation that the battery is ok, do you have a charger or booster pack you can try.

Hi yes have have put a fully charged booster pack on made no difference at all.

[Herbie]

1 hour ago, SIMMO91 said:

HELP!!!  My gs450h has lost all power to the instrument dashboard / radio won't turn on nothing working except the lights, horn,  hazard lights... doors unlock and lock ok using the keyfob but press start button nothing happens, also the streeing wheel is locked in position so can't release the streeing.  I have checked the 12v battery in the boot but its OK reading 12.7v states good on the meter. I have disconnected the earth lead for 10mins and reconnected but still no dash lights. I have also checked every fuse in all locations and not one is bad and 12v is going from battery to the engine fuse box... anyone know whats happening?

Presumably it doesn't go into READY mode so it should be showing warning messages and/or flagging OBD codes up. You need to read the codes and tell us what they are, otherwise we're just randomly guessing.

[SIMMO91]

1 hour ago, Herbie said:

Presumably it doesn't go into READY mode so it should be showing warning messages and/or flagging OBD codes up. You need to read the codes and tell us what they are, otherwise we're just randomly guessing.

There is no dash lights showing its dead completely on the instrument panel so can't get codes as there is no power at the obd port. The start button goes green but does nothing when pushed to start. The only light on is the car showing the door open that's it for the instrument panel. 

[Herbie]

14 minutes ago, SIMMO91 said:

There is no dash lights showing its dead completely on the instrument panel so can't get codes as there is no power at the obd port. The start button goes green but does nothing when pushed to start. The only light on is the car showing the door open that's it for the instrument panel. 

Then surely it's got to be the 12V Battery or the connections/wiring from it. Have the 12V Battery load tested - it may show 12.7 off load but when loaded that may drop like a stone. If you're sure the Battery is good then carry on as below.

When the brake pedal is pressed and the power/start button pushed, there are two 12V relays that act as an interlock. If there isn't enough power in the 12V Battery to energise those relays then the hybrid system can't be started and nothing will work.

Make sure the Battery clamps are clean and tight (take them off and use sandpaper/emery paper/steel wool to shine up the Battery posts and the mating surfaces inside  the clamps. Follow the cables from the Battery to wherever they go and do the same at that end. Check body and engine earth straps and also check for continuity of cables as well as voltage.

3 hours ago, SIMMO91 said:

have also checked every fuse in all locations and not one is bad and 12v is going from battery to the engine fuse box

Is it getting TO the fuse box and also THROUGH the fuse box? It could possibly be the main fuse that's blown.

Not from a Lexus GS450h but this is the type of fuse I mean:

[SIMMO91]

25 minutes ago, Herbie said:

Then surely it's got to be the 12V battery or the connections/wiring from it. Have the 12V battery load tested - it may show 12.7 off load but when loaded that may drop like a stone. If you're sure the battery is good then carry on as below.

When the brake pedal is pressed and the power/start button pushed, there are two 12V relays that act as an interlock. If there isn't enough power in the 12V battery to energise those relays then the hybrid system can't be started and nothing will work.

Make sure the battery clamps are clean and tight (take them off and use sandpaper/emery paper/steel wool to shine up the battery posts and the mating surfaces inside  the clamps. Follow the cables from the battery to wherever they go and do the same at that end. Check body and engine earth straps and also check for continuity of cables as well as voltage.

Is it getting TO the fuse box and also THROUGH the fuse box? It could possibly be the main fuse that's blown.

Not from a Lexus GS450h but this is the type of fuse I mean:

Thanks will check tomorrow for connection's 

[SIMMO91]

On 5/2/2022 at 7:42 PM, SIMMO91 said:

Thanks will check tomorrow for connection's 

Latest the car has now got dash lights steering has unlocked and centre screen is working sat/nav radio etc. It just suddenly started working next morning? BUT car won't start it's had diagnostic and has codes B2785 COMMUNICATION MALFUNCTION BETWEEN ECUs CONNECTED BY LIN....  PLUS CODE POAFA HYBRID Battery SYSTEM INTER-LOCK CIRCUIT HIGH.  any ideas please 

[steve2006]

What colour light is on the start button, Amber then green with your foot on the brake?