Jock666

Hi. ECU's were common failure on MK 1's due to capasiter leakage - does not really seem to have carried over into mk 2's though - except for the Levinson amps! All the C codes are body related - what confuses me most is why these cannot be cleared!

Simples....after drivetrain was changed my son sold the lockset and ecu whilst I was working abroad. Regardless, at no point in any conversation or on forums have I ever come across anything (I am in the Trade) even remotely blaming problems on this particular Toyota/Lexus fault with the ecu and still believe that to be so. Seems this is one of those enigmas that Toyota have had for 25 years in their vehicles and never bothered to sort....but someone out there must have!

Hi again folks. Well after 8 years I’ve gone and bought a decent scanner/code reader – Autel DS708 and plugged into our 2003 GS300. For 95% of the time we have owned this the VSC/ABS lights have been on – thought we sorted it out 3 times 1) brake fluid reservoir was 5mm low 2) the bank 2 sensor 2 oxy heater/sensor was changed 3) reset the Yaw rate sensor (even made an OBD plug up specially to make this easier as the generic code readers have been known to trigger these lights on Toyotas for some reason – they all worked for a little bit then back again. The lights normally illuminate after 1-2 mts of car movement. Now we also have the TIS Dealer software (disappointingly very basic old thing though) and both systems show NO OBD or fault codes anywhere. The abs sensors all read fine during driving. Having gone deeper into the new scanners system I go to the ABS section where the Yaw sensor can be reset and the utility allowed another fault scan and the pictures below show an alarming amount of faults!!! Physically impossible for them to be real – it also allows you to clear faults at this menu but….it does not clear them – they remain in the system! Is it possible that’s where the real culprit is living???? Now before you ask – every mechanical an electrical component on this car HAS been changed from the complete drivetrain (engine/box/diff/exhaust) to everything under the hood – all except the ECU – and despite the mind boggling cost – the exact same problem exists – by simple conclusion (bearing in mind the donor car drove with ZERO faults) is that the fault remains in the ECU - ???? Now after years of probably reading every post on the subject surely someone must have got the bottom of this cr*p system that even turns off the VSC when the cat heater senor goes faulty??? WHY??? – it’s not part of the traction/braking circuit? Is there maybe a bypass for this?? Help….because if these do not sort the problem I am going to have to scrap this amazing motor – sometimes you have to know when to let go…..

Hi. I know its been a while buy having the same problems with wifes ML amp/sat nav unit - no volume on radio. Followed up on 1 tech post that showed a blown resistor repair - but ours was fine. Did you ever post/share the details of the fault report you got for yours? Jock

2003 Lexus GS300 - what is the best (factory standard) diagnostic tool or software for the older model cars? The old Mastertech machines are thin on the ground and no updates avail since 2007 so not an option. Is it then onlt TIS thats avail??? We have numerous other high cost machines (£3000+) here that are generic OBD but need something Toyota specific for the older model.

Seriously - NO issue! You, presumeably, have never had cause to deal with it then so it cannot exist? It is and has been a major problem with the motors since year one. It is also a major safety issue as the motors completly loose power (excepting the last 25% wire control) unexplicably and without warning with no lights and no codes - and is in no way an isolated issue - hence the reason for the post "final answer". If you can name it we have changed/fixed/kicked it - and we have all the scanners you could wish for and the abillity to read them too..... Would not be on here trying to find the elusive "final solution" if we had not. Just pity as with most forums that no one ever bothers to share/give the final answer - if they ever get it - to their problem. Specifically this one. So thanks to all who have taken the time to respond constructivly but still the problem remains and hopefully 1 day we may even stumble upon the fault/cure.

Allright folks. Now some of these forums on the web are nearly 20 years old and the problem goes back to the very 1st lexus models - so why o why is there not a big screaming definitive answer as to why they suddenly loose power??????? It's been going on since begining to at least the 2005 models and forums are full of folks asking same question - so what is it? Based on research it's not: ECU, Injectors TB, TPS, MAF, Mechanical, Injector loom, Fuel pump, Relays, any sensors that we know of, and a specific fault code never shows up - so WTF is it???? Finally got so sick of it the car has not moved in 6 months. Come on all you so-called Lexus/Toyota Guru's & Dealership Mechs - tell us!

The data logger facility on our new Autel DS708 only sends the file automatically back to the US factory for later updates on their software - so no we do not have access to a data log file here. The machine was again updated today and no fault code other than usual misfire recorded. So will have to assume nothing untoward is showing to the techies.

Ref plugs - went through 4 sets diff heat before found perfect ones - car had done 80k on gas before we bought it and was fine at time of purch - prob was never on petrol though and this definetly isnt plug related. Misfire caused by lack of fuel or mixture.

Should mention only reason motor was changed was some *&(&^% in a very well known "specialist tuning shop" has it on the dyno & diag equip and stated "problem is without doubt cyls 2/3 have burned valves caused by lpg" - absolute boll*&^s! It was cheaper to pop in low mile motor than strip and redo head - but curiousity afer swap was finished......head was 100% perfect - even cc'd it and chambers were with 5% across all 6 cylinders @ 147k miles - and no leak through on valves sweet. Block was just like new. So - loads of dosh - time and aggrivation for nothing. Better still had the UK No1 trouble shooter for Denso here - what a dissapointment!!! big titles little sense.

All of the LPG parts have been tested/serviced inc emu and replaced over last 4 years - been to 2 other garages for check over with no faults found. Runs perfect on gas after we got right plugs fitted. When warm on petrol never misses a beat. The NO power problem started off during normal driving cycles - even on motorway a few times and no manifested into cold start problem. The complete engine and injection system have all been changed to a 50k unit along with new injectors, 3 maf's, oxy sensors etc etc etc - lost count of the time and money spent, And that doesnt include the £3k spent on scanner equip.... Car starts perfect (except when battery flat again afer few days....4 in 4 years) idle jumps to 1100 ish if memory serves. Can drive out the driveway for about 50/100 yds then NO power or throttle pedel - if left on petrol as stated takes a fair bit pumping (more of a placebo for my frustration & benefit than for the car!) until - feels like blocked fuel line - comes clear and takes rev. BTW last week fitted complete fuel pump assy into the tank which was pristine inside as I was convinced the intank filter had clogged! - Nothing - no change at all.

Old problem just got dangerously worse...... 03 GS300, had this prob ongoing for years now a dangerous joke. Lucky car has LPG - so get to start it & let idle until warm & gas cuts in otherwise undriveable when cold. On petrol when cold it does NOT stall or shudder at start - it starts perfect on choke, moves back/forward with power no problem. Get onto to road and ...NO throttle NO power just dies to idle appears to be in limp mode but even the little bit of wire left on throttle does nothing, then starts to hunt/drop revs etc. keep throttle pumping and after 3/5 mins it clears, gets full revs then is fine. By which point its switching to gas anyway. The EML will eventually come on only to say misfire. Not a single code from 5 different readers - including Lexus - has ever pulled a code for us. What we did learn was that the TCT light is constantly activated by the YAW sensor - which even though got changed - still comes on so gets reset every week or so - the joys of Lexus ownership. So - to the NO power problem - suggestions other than the usual rude ones I tell myself......

Hi to all again.