Mihanicos

Hi, I agree, inverters do generate a lot of heat instantly and the coolant should be able to absorb it. Upon further reflection, may be the coolant is not circulating fast enough to remove the heat from the inverters. At the same time, the engine and the inverters share the same cooling system, and if the engine has developed gas blow by from the combustion chambers due to piston wear, this would contribute to more heat added to the coolant. Gas blow by is more intense under hard and severe acceleration. You can check this by removing the engine oil filler cap momentarily and see if there are any gases coming out. Engine oil consumption is another indication. Beware of oil coming out usually from a nearby camshaft. However, this heat from gas blow by should not cause an immediate coolant temperature rise as that due to inverter heat generation. Whenever the cooling system is opened for any repairs, replacements, you must make sure the heater is fully on and bleed the air from the heater radiator by squeezing the flow hose into the heater radiator while the engine is running, with the engine thermostat open and the radiator cap off. As you squeeze the hose the coolant level in the radiator should fluctuate. keep doing so until the coolant level changes to the slightest squeeze on the heater hose. Any trapped air in the heater radiator will compromise the coolant flow and this will hinder efficient coolant flow. Another point to consider is the water pump impeller being worn out, a very remote possibility but I have seen some cases totally unbelievable. As long as the expansion tank has coolant in it, any air in the tube from the radiator to it should bleed out. The volume of the coolant when it expands is more than the internal volume of the tube from the radiator to the expansion tank. Check the water temperature sensor by immersing it in water and reading its resistance. At 20C, the resistance between its terminals should be 2.32 to 2.59 K Ohms. At 80C " " " " " 310 to 326 Ohms. Replace the sensor if the readings are not within specified range. Chris.

Coolant replacement is at 100,000 miles irrespective of time, please accept my apologies for my mistake. Make sure that you have no leaks at all because this would reduce the system operating pressure and this in turn would lower the boiling point of the coolant. Once the coolant boils within the system, more coolant will be released from the radiator cap leading to less mass of coolant which in turn raises its temperature causing further boiling. At standard atmospheric pressure pure water boils at 100C. Chris.

Hi, From the data of the engine active test, the coolant temperature range is between -40C and 140C. Normal range is between 80C and 105C after warm up. A note about the temperature sensor states that if the displayed temperature is 140C, then the sensor is short circuited. If it displays -40C, then it is open circuited. It may be worth checking the sensor although from your description it seems to be ok. Sometimes a short circuit occurs at higher temperatures than normal. Another point to consider which is critical, is the radiator cap, and if it opens at a lower than specified pressure, this leads to coolant boiling at a lower temperature. If this happens, then the rate of heat rejected through the radiator is reduced proportionally. Hence a rise in the coolant temperature. I would suggest that you check the inverter cap and make sure it is within specifications. [ Range : 15 Kpa to 44Kpa ] Minimum 12 Kpa. If it opens at a lower pressure, replace the radiator cap. Check that its vacuum valve is not stuck and free to move. Also make certain that everything is clean a free from any rust deposits. The coolant should changed initially at 100, 000 miles or 10 years of life whichever comes first. I hope the foregoing will be of help to you. Chris.

Hi, The freeze data gives you three sets of readings before the DTC, one set of readings when the DTC was set and one set of readings after the DTC was set. These data are given in 0.5 seconds intervals. Since the DTC refers to the fuel pressure high side, the readings you have refer to the fuel pressure high side. Using the Techstream, alter the fuel target pressure and observe that the fuel pressure fluctuates. you can lower the target pressure by 12.5% and increase it by 25%. If the pressure changes by the exact amount, then you may have a faulty ECM. If there is no change, then you must check the fuel relief valve and its relay. During these tests you have to put the engine on inspection mode. Put the gearbox on P. Press twice the accelerator fully. Move lever to N and press accelerator fully twice. Move the lever to P and press the brake pedal and the start button simultaneously. The engine should start and you can vary the engine rpm up to 2500. Always start with the easy tests and with the cheap replacements. Good luck. Chris.

The DTC occurs when the fuel pressure on the high pressure side is too low. Fuel pressure is achieved by a mechanical pump driven by a camshaft and is regulated by the spill control valve. A fuel pressure sensor monitors the pressure and is regulated between 4 and 13 MPa. If the pressure is lower, the ECU closes the spill control valve. If the pressure continues to drop, the ECU blocks the power to the spill control valve so it remains open and regulates the engine to a max of 2000 rpm. Check for fuel leaks on all pipes of the fuel system after the high pressure pump. [ Fuel pipes to direct and indirect injection injectors. Fuel injectors leaking.] ] Fuel pressure relief valve. Fuel relief valve relay. Fuel pressure sensor. Fuel pump for high pressure. To carry out some tests you will need the techstream. Kindest regards, Chris.

Intermittent noises and vibrations are very difficult to locate and eliminate. Try raising the car on a lift jack or on stands and put the engine on inspection mode whereby the engine runs continuously and you can vary the rpm with the accelerator. If the symptoms occur under no load, you should be able to pinpoint what you are looking for. For a GS 450H , the inspection mode is achieved as follows: 1. Turn the power switch ON (IG) . 2. Move the shift lever to P and then depress the accelerator pedal fully twice. [ If the shift lever is already at P position, just press the accelerator pedal twice ] 3.Move the shift lever to N position and press the accelerator pedal twice. 4. Move the shift lever to P position and press the accelerator pedal fully twice. 5. Check that " maintenance mode " is displayed. 6. Turn the power switch ON ( READY) and the engine should start. 7. To deactivate the inspection mode, turn the power switch OFF. Wishing you the best of luck, Chris.

My car has also a " sealed for life " gearbox, as stated in the owner's manual. However in the maintenance schedule of the repair manual of Lexus published by Toyota-Lexus [ Lexus-tech.eu ], for my car, it is stated that every six years or 72 000 miles ( I am not quite sure of the mileage but it is somewhere around there ) the transmission oil should be changed. Log into Lexus-tech.eu and you will find there all the information you need.

When new, my car used to do 43 miles to the gallon. As the years went by, this figure kept going down and by coincidence when a maintenance item was carried out according to the maintenance service schedule. eventually it dropped to 40.4 miles to the gallon and two months ago, I used to get " check VGRS system " and the car would not start on the first time. I used the techstream and no trouble codes were present and the VGRS system was ok. However there was a message that the 12v battery was low with only 10 volts. I charged the battery to the full and the car started without any codes. It run for a few minutes and the engine stopped, normal behaviour. After a few minutes , the engine started again and it should not have done since the car was stationary in the garage. This only meant that the 12v battery needed to be charged. A check on the battery revealed 10 volts. I had the battery checked and it was not up to specification. I put a new 80Ah ordinary battery and not the original Panasonic and the car now does 42.5 miles to the gallon. I was convinced that the hybrid battery was in need of maintenance and I was planning to do so in a couple of months when the weather improves. I never thought that a bad 12v battery would make so much difference in the fuel economy. Chris.

You will find all the information you need in Lexus-tech.doc. It costs about 6 Euro per hour of looking up repair, maintenance and scheduled service information. You can also print anything you want. I have already changed the ecvt transmission oil in my car according to the maintenance schedule.

You must check the power battery voltage, it should be about 300 volts dc. If not, you probably have an open circuit somewhere along the series connections on one or more individual cells of the battery. Check that all your connections are correct and good. If you have access to a Techstream or a similar scanner it would be a great help. Chris.

Make sure that the 12v battery is fully charged. Regards, Chris

Make sure that the tyres are inflated to the correct pressure. I inflate my tyres to 2.8 bar, ( about 41 psi ) according to the owner's manual. If your tyres were under inflated, In my opinion, the damage would have been caused by full power acceleration or when getting up on a curb. This can also be caused when getting back on the road from a lower than the road curb. Sometimes it could be a bad quality tyre.

Assuming that the scanner could read all the codes, this eliminates any malfunction of the car. The only variable that can fail to start a petrol engine is the fuel. I strongly suspect that somebody put diesel fuel in the car and not petrol. The mechanic mentioned that the fuel had a peculiar smell and taste. Take a sample of the fuel for analysis or simply drain it and try again with petrol. It will struggle to start until the fuel lines are cleared from the existing fuel.

Merry Christmas to all. Not all trouble codes are displayed on the instrument panel. To eliminate all guess work, I would use the Techstream scanner, the Mongoose or the one used by Lexus. Intermitent faults usually indicate bad contacts at the connectors. By removing and reconnecting the connectors a good contact is restored. Never believe that anything in this real world lasts for life! My car's owner's manual states that the gearbox is sealed for life and no maintenance is required. However if you refer to Techdoc ( Lexus repair manual ) it specifies that the gearbox oil should be changed every 72 months or some 60 000 miles, I am not quite sure of the mileage but is around there. Refer to Techdoc for your car and follow the directives. I would most certainly change the oil with the recommended oil by the manufacturer and not by any other claimed to be superior, better etc. I would also disonnect and reconnect all connectors to the gearbox. Also check any damage to the multicore cables pertaning to the gearbox and repair as necessary. Moisture and water is the cause of all electrical and electronic equippment. Kindest regards, Chris.

From personal experience, every time I go abroad for three continuous months my car starts every time first time. If the 12v battery is flat, all it needs is charging and then the car starts. In your case, it is possible that the HV battery is not charged properly or, there is a current leak from the HV battery to the ground. This would indicate damaged HV cables from the battery to the inverter converter and from the gearbox. Testing the battery power output will eliminate the remote possibility of being damaged. A techstream scan would be a great help. Normally a visual inspection of the orange cables underneath the car running from the HV battery and the gearbox to the engine compartment will show any damage to the cables. To carry out the foregoing you must be competent with electricity. You also need the right equipment to do it. If you need more information and precise details how to locate the fault, I will be more than happy to help you. Kindest regards, Chris.

I agree with the recommendations of all other members. Tire unbalance usually occurs between 50 and 60 mph. But if there is a steering damper fitted on the car, probably this will not be noticed. Check that the steel belting of the tires is sound and not ruptured. Jack each wheel up and rotate them. Make sure that there are no bulges anywhere on the tire and that its circumference is fairly true. With time and increased mileage there will be a noticeable wear of the rubber at the bulge points. This will not be visible at the beginning. Taking advantage of this opportunity, check that there is no play at all on the bearings of each wheel. Regards, Chris

You are absolutely right! I stand corrected. I apologise for the wrong information. Chris.

This ecvt gearbox has a filter in it and it is made of a fine steel mesh. Given that the owner's manual states that the transmission fluid needs no change and the Techdoc maintenance schedule calls for transmission fluid change only and not the filter as well, then this should suffice. I have another Toyota with automatic transmission and I changed the filter as well as the fluid. I bought the filter before I removed the transmission pan and both were made of a fine steel mesh, exactly like the one for Lexus. The car had done 150 000 Km and the filter was clean and there was no difference between the new one and the old one. I put the new one in and there is no difference in the transmission performance. With this in mind, I opted out not to change the filter on the Lexus for now. The ecvt transmission is not like a conventional automatic transmission with clutches. Regards, Chris.

In the owner's manual it is stated that the gearbox is sealed and the fluid is intended to last the car's expected lifetime. However, if you look up the maintenance and service schedule in the Lexus Techdoc, depending on the region the car is being driven, you will find all the relevant details. In my case, it needs a transmission fluid change every 72 months or 70 000 Km ( I am not quite sure about the Km but it is not far off there ). I had 42 000 miles on the clock and the oil that came out began to change colour, pale red. I also found out that it had less oil than the right amount, somebody attempted to check the fluid level without first circulating the fluid through all the gears and probably at a higher temperature than 40C. The 5mm allen key plug which is removed to check the fluid level was very tight whereas the 14mm drain plug was at specified torque. This a clear indication of what had happened. Now with the correct amount of new transmission fluid it operates like before and when braking down hills, all the gears hold the car very well with constant braking, the position of needle of the Kw meter remains constant in the blue range corresponding to each gear being used. Bear in mind that in an ecvt hybrid gearbox the electric motors MG1 and MG2 generate a lot of heat when in traction or generating mode. The transmission fluid is intended to cool them and lubricate the bearings. Channels and pipes within the gearbox make sure that the windings of the motors get a constant supply of oil to cool them. Kindest regards, Chris.

Dear Hangie, Thank you very much for reply. I changed the transmission fluid myself according to the guidelines in the relevant Techdoc publication. It was not difficult but if you need to add fluid, you have to disconnect the rubber hose connecting the oil pipe to the oil cooler, adjacent to the gearbox. Had it been a filler plug available like in other models, you simply add fluid at a temperature between 30 C and 40 C it trickles from the drain plug. In the Techdoc publication it is over stressed in every step of the guidelines in red letters to make sure that you have no line pressure in the fluid filling process. I had had no line pressure DTC so everything was ok. To do this job you need the Techstream. Kindest regards, Chris.

Hi everybody, my car is due for a transmission fluid change and I cannot find the filler plug. I looked everywhere except on the top of the transmission which is impossible from underneath the car. The Lexus Techdoc suggests to disconnect a small rubber hose about one foot from the gearbox on the fluid line to the oil cooler and fill the transmission from there. There has to be a fluid filler plug because without that, the fluid level cannot be adjusted if its temperature is not within the 30 C to 40 C range. A special tools is connected to the filler plug to to add fluid or apply vacuum so no fluid drains from the pan when the drain plug is removed in order to connect to it another special tool which compensates for the fluid level at higher temperatures.

You can use either. You can also use the old gasket by applying a gasket sealant on top of it if it is still stuck to the pan or on both sides if it is free. Make sure that the gasket sealant you apply is compatible with the gasket material.

Normally, faults that bear no relation to each other, for a specific code, point to bad ground connections. Trouble codes that are cleared and return immediately are permanent indicating short or open circuits relevant to the code in question. At this instance, I would make certain that all ground connectons have an almost zero resistance to the 12v battery negative terminal. A ground connection wire is connected to all the car's Ecu and you must find it and check itq. A 5v reference voltage is established at the car's circuit which is used for signal purposes and data collection from the various sensors. Each Ecu sends and receives 5v pulses for various purposes. Make sure this reference voltage is available and stabilised. Refer to the circuit diagrams of the car to identify the ground, 5v reference voltage and all relevant sensors qwiring connections pertaining to the codes in question. Sometimes by pulling out the multipin connectors to the various Ecu and reconnecting them will improve contact resistance. Good luck!

Remove the connectors to both rear wheel sensors and with a multimeter check their continuity and insulation to ground. You should get very nearly the same readings. If not the replaced sensor is faulty. With the ignition ON and the engine OFF, check the voltage readings of each wire on the connectors to the sensors. You should get identical readings, these wires come from the ABS ECU of the car. Check also that you have no fuses blown relating to the ABS ECU . Check that these readings are also available on the pins of each connector to eliminate the possibility of an open circuit at the connector. It is very likely that you have an open circuit at the connector which occurred when the ABS sensor was damaged. The linear valve offset can be recalibrated with the Techstream or another good scanner like the Autoenginuity. It takes a few minutes and the scan tool will do it without any intervention from you. Regards, Chris

Thank you very much indeed for sharing your knowledge and experience with me. Your threads were very enlightening and the videos explained very clearly in detail how everything works. I knew that the braking was regenerative through the motors but I did not have a full drawing of the car's gearbox to understand how everything works. I bought viewing time from Lexus website to look up relevant information but all I could access was how to change gearbox oil. I will check the car's behaviour in the next few days and I will know if it is back to normal. I take this opportunity to thank you for your help and the Lexus owners club of uk for hosting me. Chris.