RX 300 with a raft of problems!

[gemmia]

Hi All, I'm brand new here and not sure if this post is int he right area so please forgive me if not. I used to own an RX300 (2003) that I gifted to my father when I moved on to a newer vehicle. The problem is when the RX has an issue it becomes my car again and that's the case as of this weekend! It appears to have a list of issues as long as my arm all point to an electrical issue but the problem is where to start, I'll list the symptoms and codes below:

Symptoms:

Radio comes on and tunes but has no audio - Sat Nav has audio

The instrument panel lights (not ignition) do not come on until the car is taken out of neutral

When drive or is selected both the drive and neutral lights light up for anything from 20 seconds to circa 60 seconds then drive only

It will stall out when shifting to reverse from drive or drive from neutral, will restart in park and be fine as long as it stays in drive or reverse.

Fault codes 1-8 I'm not sure if the sequence is relevant:

1)P0335  2)P0340  3)P0345  4)P0705  5)P0335  6)P0340  7)P0345  8)P0705

So basically 4 fault codes which if my modest reader is correct are:

Crankshaft Position sensor, Camshaft Position Sensor & Transmission Range Sensor.

I've been through all the fuses in the passenger bay and engine bay, they are all good 

I should add that the car has an LPG conversion, originally in 2006 and then refreshed in 2014.

When in drive and running it pulls as it should and gives no issues, i.e. missing or stalling. Check engine and VSC lights are permanently on and fire back up moments after clearing the faults.

I'd appreciate any insight anyone might have as to whether one of these components could cause all these issues!

Thank in advance Dan  

 

 

 

[m4rkw]

Welcome to the forum!

This is indeed quite a list. First important question - does reverse work ok and does the transmission shift all the way to 4th without issues? How many miles are on it and when (if ever) was the transmission serviced? The reason I am asking these is because if the transmission is healthy then it's probably worth trying to address the other issues. However if the transmission is failing (slipping, delayed engagement, not shifting into high gear or shifting at odd points etc) then you'll probably want to first determine where you stand with the transmission before deciding to do anything else. Some transmission problems can be caused by solenoids external to the transmission itself which aren't the end of the world to fix, but an internal problem would be very expensive. Given your description however it sounds like the issues are probably electrical.

The LPG conversion may be screwing with things, is it possible to turn it off and see if that changes anything?

The crankshaft and camshaft position sensors are probably relatively cheap and easy to replace so I'd probably start there. I would first want to make sure that those codes can't have other possible causes than duff sensors though. I just had a quick check and it seems these codes can have many possible causes. I think your best bet would be to take the car to a Lexus specialist (independent to keep costs down, since it's an older vehicle) and have them diagnose it for you. Tell them the symptoms only, not what you think might be wrong with it, and try to give them as much information as possible. Them see what they come back with and go from there. They will probably test drive it and can then tell you if there's anything amiss with the transmission.

Taking the codes on face value, three sensors probably wouldn't be a major repair however error codes can be misleading and sometimes have many possible causes.

Keep us updated!

[m4rkw]

Thinking about this more - multiple sensor codes and weird electrical issues all together may be more likely a wiring issue or a bad module somewhere than issues with the sensors themselves. This is one of those situations where you could easily throw money away by trying to fix it by taking the errors at face value. I've made this mistake many times in the past before I learned - eg replacing every sensor that showed up related to an error code. If it's a wiring issue this will have no effect, or worse the issue could go away temporarily (because you moved the broken wires around while replacing the sensors) only to return later and cause even more confusion.

If there are no symptoms of mechanical problems and all the issues seem electrical then it may be best to take it to an auto electrician first for diagnosis as they'll be in a better position to diagnose wiring issues and other complicated electrical faults.

[gemmia]

Hi Mark,

I was considering taking it to an auto spark for advice.

To answer your questions:

The vehicle has done 165000 miles I don't believe the transmission has ever been out of the vehicle for service, just routine fluid & filter changes I'm assuming.

It's starts fine, shifts fine and drives fine both forward and reverse. The only mechanical issue is that it will stall if you change the gear i.e. start, reverse fine then pull it out of reverse into drive and will still instantly. The same is true if you take it out of drive and try and select reverse.

It's now started putting the neutral light on with any selected gear, D/R/M which is either new or I've never noticed that before 😁

Turning off the LPG does nothing to solve the issues it's the same using Petrol or LPG. This has been an issue before if there has been a fault on the LPG system it's does manifest some strange codes but using it on the original petrol side clears those and highlights that the issue is the LPG system. This time it's both systems!

I appreciate the input though. The radio side of it is really throwing me but does suggest it's a wiring problem, do you know of any other amp fuses not located with the main fuse boxes?

Cheers Dan  

[Herbie]

When you say you "turned off" the LPG system did you pull the fuse to do that, because that's the only way to really turn it off. Having said that, given so many things wrong at one time I can almost guarantee it won't have anything to do with the LPG system - this is just screaming electrical to me.

First thing to check is the Battery. Even though it's not a hybrid it still has lots of complicated electronics that are very sensitive to Battery voltage being just right and can throw all sorts of wobblies if it isn't. First thing I'd do is to charge the Battery overnight to make sure that you have a good starting point for any tests. Make sure that the Battery posts and clamps are clean and good tight connections, and the same for the 'other ends' of the Battery cables too, along with the engine/tranny to chassis earth straps.

The chart below shows 'standing voltage' with the car off. Next, fire up the engine and make sure that the alternator is doing its job - voltage should be about 14.5V.

 

Once you're sure that you've got a good electrical baseline, if that hsn't cured the problem start looking for any signs of dampness, water ingress and/or corrosion around or on ECU connectors.

However, in all honesty and with so many things affected, I would be inclined to take it straight to a proper auto electrician. They have the proper knowledge, skill and test gear to sort something like this in a fraction of the time it would take you or me.

I see you're in Lancashire so if, like me, you're in Preston, I can highly recommend Ribblesdale Auto Electrics on Marsh Lane https://ribblesdaleauto.co.uk/about-us/ Their website is rubbish and I have no idea what they're doing with it, but their auto electrical work is first class.

Good luck and please keep us informed of the outcome. I hate it when we're left in limbo wondering what went on

[m4rkw]

Hi Dan

By service I meant a fluid and filter change, I don’t think there’s any reason to remove the transmission from the car unless it’s faulty. Ideally the fluid and filter should be done every 50k miles or so, if yours has been done a couple of times that’s good, hopefully the transmission is in good shape then. If it had done 165k without a fluid change I’d be concerned. It seems unfortunately common for this to be overlooked because manufacturers like to say their transmissions are “sealed for life”. Although this is technically true, the manufacturer has a very different opinion on what the expected lifetime is than you’d ideally want.

The symptom you describe when changing the shift selector sort of makes sense in the presence of the transmission position sensor code. It sounds like whatever signal is supposed to be communicated when the shift lever is changed is somehow missing or confused and causing erratic behaviour. Since it does shift into drive and reverse, perhaps that signal is getting to some part of the system but not another, causing the weird dash lights and the stalling. Maybe if that signal is missing it cuts the engine out to try to protect itself.

Likely candidates are a wiring issue somewhere, a bad module or bad sensors. In any case an auto sparky seems like your best bet.

I’m afraid I don’t know if there are fuses located anywhere other than the main fuse board but you could try looking on toylexparts.com. It can sometimes be difficult to find the relevant diagram but a good trick is to search for the thing you want generally across the site, eg “fuse”, which will yield results for many vehicles. Then look at what diagram sections those results appear in and then look up the same section for your specific vehicle.

Mark

[m4rkw]

Really good point about the Battery Herbie, dunno why I didn’t think of that!

[Herbie]

5 minutes ago, m4rkw said:

Really good point about the battery Herbie, dunno why I didn’t think of that!

Cheers Mark, and just to prove my point to the OP, this is taken from a post in our 'sister' Lexus Owners Group on Facebook - the last post says it all:

[m4rkw]

Halfords will test a Battery for free.

[gemmia]

Thanks for the tips guys, I'll have the Battery checked at Halfords and give Ribblesdale a call, I'm in Ormskirk so not too far away. I've taken to two local auto sparks this morning one can't look at it until the middle of the month and the other didn't want to know! I'll keep you updated as things progress 🤪

[m4rkw]

What kind of auto sparky doesn’t want to look at an electrical problem?!

[gemmia]

One with too much work I guess 😡

[Spudd]

Had this issue with my rx 300 when i bought it. We removed  the foot well side kick panels disconnected  all joints and cleaned. We also cleaned up all the earth points and connections we could get to and all ok now. Think the problem caused by sunroof pipes being blocked.

[gemmia]

Hi Spudd, thanks for that I'll give it a go - nothing ventured noting gained.

I've had the Battery tested at Halfords and it's AOK, apparently it was replaced in February this year so all good there.

I also took it to Ribblesdale this afternoon. Despite speaking to them this morning, outlining the problem and telling them what vehicle it is, I arrived to be told - "we can't help you we don't have any software for the gearbox on a Lexus you will have to take it to a dealer"! Very frustrating and not my historical experience of Ribblesdale, they are normally on the ball.

So that brings me to the next question, should Spudd's suggestion not work, does anyone know of an independent Lexus specialist in my neck of the woods, Lancashire, Cheshire, Merseyside, Greater Manchester or anywhere really, that might be able to help before I mortgage up for a trip to Lexus....

Thanks again 

[Mihanicos]

Check all ground points of the car. Also check that all ground pins on the OBD socket are good.

Chris.

[Herbie]

1 hour ago, gemmia said:

I also took it to Ribblesdale this afternoon. Despite speaking to them this morning, outlining the problem and telling them what vehicle it is, I arrived to be told - "we can't help you we don't have any software for the gearbox on a Lexus you will have to take it to a dealer"! Very frustrating and not my historical experience of Ribblesdale, they are normally on the ball.

Very poor but also very unusual - as you say, they're usually well on the ball.

Sorry it didn't work out for you Dan.

[m4rkw]

This thread reminded me of something that happened years ago on a beemer I used to have. One day I went out for a walk and returned an hour later to find the car on the driveway where I'd left it, with several of its rear lights on. I had the key in my pocket. .was like what the hell? I opened it and looked inside and the instrument cluster was lit up like a christmas tree with all kinds of crazy lights. Very confused I drove it over to the garage and they asked if I'd had it valeted recently - I said yes as it had just come back from a valet. It had cloth seats and they were still damp - moisture had gotten into the fusebox and played havoc with all kinds of stuff. All they did to fix it was dry it out.

I'm guessing it's probably a long shot since you've not reported any damp in the car and the problems seem to have been ongoing for a while, but it wouldn't hurt to turn the heater up to max and leave it for an hour just to see if anything changes. The other suggestions about checking grounds are probably better things to try first though.

I was thinking again about the symptom where the N light is always on regardless of whether the car is in D or R. Maybe each of the gearbox states (P/D/R/N) has its own signal wire which would be either high or low when that state is selected. If the N wire is shorted then that signal may be always present regardless of the lever position, which would explain why N and D/R show up together and why the car stalls when moving out of D or R (protecting itself because it gets confused by in-gear and neutral signals happening at the same time).

This is a complete guess as I have no idea how the system really works, but if you can find a wiring diagram for it it may shed some light. 2003 is the crossover year, is it a gen1 or a gen2?

[m4rkw]

I found a wiring diagram for a 2000 RX-300, check out the bit I've highlighted. "Park/neutral position switch" I think this is the switch that the shift lever operates. Notice it has "RL", "NL" and "DL" pins that it can switch between. Those must be "Drive line", "Neutral line", "Reverse line", and they're all right next to eachother, so my theory about separate signals for each shift state seems to be correct. I reckon you probably have a short there somewhere, either between DL and NL, RL and NL or all three. Not sure what would be easiest to access to test this, maybe someone else on here knows? Either the switch itself, the junction connector J8 or the ECU. I'm not sure exactly how to interpret the ECU pin connections, RL seems to go to 8(A), NL to 7(A) and DL to 16(A). Don't know what the (A) means. If you can figure out where you can get access to the DL, RL and NL pins you can use a multimeter to check for a short. I think out of an abundance of caution if I were going to do anything like this I would probably disconnect the Battery before going anywhere near any wiring. Also I'm totally unqualified so please don't blame me if you break anything! 🙂

[m4rkw]

http://europe.toylexparts.com/lexus/521220/mcu35r-awagkw/235w/002/4/8410/845449a#box_84722

Looks like that switch is right underneath the lever. Might be simple enough to pull the lever assembly out to access the switch and check for shorts on it there?

[gemmia]

Thanks for all the input and suggestions everyone. I took the kicker panels off over the weekend and cleaned all the connections. Went through the vehicle to find, examine, clean and re-seat as many earths as I could but I'm no expert so I'm not really sure if it helped. Bottom line is I need to find an auto spark who can go through the vehicle properly with the right kit and one who hasn't diagnosed it as a lost cause before I even get there. Any suggestions, I'll pretty much take it anywhere but I'd like to find someone within 50 miles of me, I'm in Lancs postcode L40 ........

[gemmia]

Hello All, and happy new year😊. Just thought I'd bring this up to date, no change I'm afraid but I've learnt loads about the car and its niggles. It spent 3 weeks with an Independent Lexus Garage and they replaced the park / neutral switch and tested the wiring / earths all to no avail. They told me that they have a relationship with the local Lexus Dealership and took it there. Lexus recons the ECU is damaged and needs replacing but at circa £3k that's not worth doing and I got the impression it was a guess anyway. I've toyed with the idea of removing the ECU and having it bench tested and repaired if possible but sadly I'm running out of enthusiasm and time. On the positive side I'm down to 1 error code P0705, the rest appear to have been eliminated by whatever the Indy garage have done, but the symptoms are all the same.

As a last ditch does anyone know of anywhere to get the ECU looked at?   

[Barry14UK]

No harm in seeking advice from somebody like this https://www.ecutesting.com/categories/ecu-testing/?gclid=Cj0KCQiAlsv_BRDtARIsAHMGVSY18_bnkE_2wsXpO57rJpWLICLMtdp7EYWdDPViWTvd-Kl5k0NS2KkaAgsaEALw_wcB

[Spudd]

I paid £130 off eBay for ignition kit key/barrel ,immobiliser control unit and ecu. No need to programme. Car stood for 10 months and started first turn of the key. 

[Stupot]

I used this place to replace the capacitors on my old LS400 ECU... you will have to remove the ECU yourself

https://www.dieselecurepairs.co.uk/