Drivers Door Control Problem - Help Please!

[johnatg]

Not really. I sometimes thought that maybe the indicators didn't flash when I locked up. BUt that was about it until the morning when the mirrors didn't deploy and then it went downhill rapidly from there.

[toffee_pie]

the mirrors could be jammed? causing the over load on the junction box?

[johnatg]

No sign that they were the first time, but it's possible. But not this time - I opened the car yesterday (that was the first time since I'd driven it home from Lexus) and left it single locked - ie mirrors deployed.

So whatever it was, it was nothing to do with the mirrors last night.

[Ashpoint]

I will post you a T-Quick harness.with the recommendation that you install the Red, White and Blue wires of the harness into the car. The three connections by themselves will go nowhere in the car and won't cause any issue.

Then, after your car issue is resolved and at your whim, you will only need to lift the Mirror/Window Control Panel off the door and enable or disable the Po-40. Less than a 5 minute exercise!

BTW: Mail from Sydney to the Uk has been running about 6-7 work days.

Michael

[johnatg]

Many thanks, Michael.

[Ashpoint]

I submitted your thread to the technical expert in Bangkok for the Po-40 Folding Mirror Kit and asked for his opinion. As I said elsewhere the answer to one question usually ends up with more questions!

The ecu/junction box has influence over a number of functions and I'm attaching some source documentation for your perusal.

On the face of it, Lexus might find that another replacement junction box will solve the problem. We don't believe that you should have a solution without a diagnosis and that means that they have to work out the cause of two junction boxes burning up.

His intuition relates to the door close sensor – the sensor on the door striker that determines whether the door has been closed or not. Your early observations relate to symptoms that are usually attributable to the wire to that sensor touching chassis somewhere in its travels.

Apart from that, they would be interested to know how and where you joined the Po-40 red, blue, and white wires.

I asked about the freezing conditions and his comment was "where are all the other IS250s with the same issue?"

I note that we have some very well educated electronics experts browsing the forum. It would be interesting to get their take on the matter.

Regards,
Michael

DLC-RHD.pdf

IL-RHD.pdf

[johnatg]

Thanks for the diagrams Michael. I can't see that they show the switch panel in the drivers door - I would like to know how that connects in to the junction box or whether the switches operate the locks and windows directly. It puzzles me that the locking switch locks and unlocks all the door esxcept that it won't unlock the drivers door. I'm beginning to wonder if the door unlock motor in the drivers door is the problem.

I think the 'RH door' indication is a syptom rather than a cause. It now shows 'Trunk open' too. A short in the wire to the sensor would just show 'RH door' all the time (ie just as if the switch was made) - that would prevent the doors locking but not affect the windows and it wouldn't burn out the junction box.

PO-40 connections (following instruction 5.2, 9 wire) - Red PO-40 to Blue of connector B (big type) . I connected it about three inches from the connector inside the trunking.

White PO-40 to Light Green of connector C - connected just before the plug near the back of the drivers door.

Blue PO-40 to thick White of connector C , again just before the plug near the back of the drivers door.

All T-connections made by cutting the host wire then inserting two wires in one end and one the other of a crimp connector.

As for 'where are all the others' I have been contacted by someone else with exactly the same problem but he doesn't want to say too much about it at present. It's a 2009 pre-facelift, but a different part number for the junction box. Having said that I don't believe frozen mirrors were the problem - everyone (in N Europe at least) would have had the issue by now.

[toffee_pie]

why has a fuse not blown, rather than the junction box?

after seeing the diagrams Mike put up I wish you well in finding the fix!! :$

I have a PO40 installed and have noticed no problems, the only way I could see that being an issue if there was a poor connection or a short to ground but that seems ruled out.

[johnatg]

Good question!

Most of the fuses 'protecting' these circuits (in fact protecting most of the Lexus electronics) are pretty high value - eg 10 - 20 amp.

You can get a hell of a lot of power (140W +) through that without the fuse blowing - but plenty enough to overwhelm delicate components - I guess - don't you think? I suspect all the power needed to drive eg the door lock motors goes through the junction box.

[Ashpoint]

why has a fuse not blown, rather than the junction box?

My thoughts exactly.I could write off the first episode with the junction box as perhaps spontaneous death by a component.

But...the second time -

Surely there was a fuse that was designed to sacrifice itself.

[Ashpoint]

Are the door locks Motors or Solenoids?

Less/more power for solenoids?

[toffee_pie]

pretty sure all the relays and actuators on both doors and mirrors etc have fuses, its something i would ask the lexus guys also.

The part blown looks like a diode or capacitor, why did it blow? probably because its ratings were exceeded probably, in fact you are rather lucky it could have smoked the whole car if you were really unlucky as the damage to that part of circuit board looks well and truly toast

[johnatg]

Theories - theories. What I've come up with is that maybe the door lock motor in the driver's door (incidentally - the Workshop manual describes them as 'motors' rather than 'solenoids', and indeed they run in opposite directions for locking/unlocking and I think motors are usual) has too low a resistance.

The WM specifies that the resistance between terminal ACTD (see the first diagram of Michael's a few posts back) is greater than 10 K ohms. If it's less the motor will draw too much current. And the socket known as PL1, which is on the Junction box and is where the door lock circuit plugs in, and where ACTD is terminal 4, is at the epicentre of the burn on the JB circuit board.

(BTW - it is where the PO-40 was connected to - Light Green in the car at Connector C to White of the PO-40. The instructions do say that European cars 'may work better with White connected to Thick Red of C'. But mine did work OK - apparently. Did.)

Anyway, I discussed all that with the technician who worked on my car this am - I don't think he was too impressed with me advancing my theories, but he is mortified that a job he has worked on has come back so soon.

He did say that the JB works on 5v - that may be true, but surely the power provided to the motors will be 12v so there must at least a 12v power bus in there along with the 5v electronics?

I've yet to hear any news....

[Ashpoint]

John, the T-quick harness left Sydney yesterday (our Monday) you should anticipated it in your hand around 29 January

Motor/Solenoid? In my IS250 (which I have just sold <sob>), the Lock/Unlock action certainly sounds like a single fast pulse solenoid and not a motor.

<<... not too impressed with me advancing theories>> Precious huh? But let's give him some latitude since he is facing the return of the job he worked on (always a frustration). IMHO, the client is entitled to an explanation. Having said those things, the dealership deserves compliments for allowing you and encouraging your contact with the man who is actually working on the case.

Looking forward to your successful conclusion.

Best regards from Down Under

[johnatg]

Quick update: The Junction Box fitted last week was burned in much the same way as the original (but I haven't seen it). Basically now they haven't got a clue. They've consulted Lexus tech - the first thing that they want is the door wiring loom replacing so that it is 'as new'. That's gonna be about £250 for the parts (+ labour).

Watch this space......... :(

[is200 Newbie]

Might be cheaper replacing the car ....

[Ashpoint]

John, thank you for keeping us in the loop. It's a good development that Lexus are now involved in the problem-solving.

They clearly now think that there is (or was) something in the door that caused the issue. Replacement to a known factory good harness is a logical move.

I wonder if the replacement door harness includes any solenoids, motors, sensors, etc OR just a bunch of wires and connectors.

[toffee_pie]

replacing it for a new car is a bit OTT..!

Keep us updated on the loom, have you got a replacement car?

[johnatg]

Another update - getting a bit p***d off now - door loom is on back order and should be delivered on the 29th. Meanwhile - nothing happening and they still haven't got a clue as to what is actually wrong (they don't really suspect the loom - it's just that Lexus tech won't help until the car is back to standard). I can see this ending up costing more than the car is worth.

I haven't been supplied with a replacement car but I don't really need one.

[toffee_pie]

tbh, you are wasting your time taking a 06 lexus to a main dealer, (yours is 06?), going to a decent local electrical guy might be better, its an electrical fault not a mechanical one.

the labour costs would not justify taking a 9 year old car to a main dealers.

[is200 Newbie]

John .. I have a Po-40 fitted and has been for quite a while now.

How long have you had yours fitted? I don't mind taking a look at the way mine is installed and taking pictures or notes on wiring and also if the fried junction box is easy to get to (do you have the exact location) I will have a look at that as well if it will help...

I have been down the road with the expense of Lexus parts and the long lead times they quote in getting them so I know exactly how you feel about this, probably want to get rid of the car as I did but there will be a resolution I am sure

[toffee_pie]

I dont think its his PO40, he has had it removed, it looks like one of them mare electrical issues you could be days at.

I would take it to an auto electrician and agree on a rate.

[Ashpoint]

Upon reflection the decision to go to the Lexus dealer rather than to a local, favoured auto electrician still seems sound to me. The problem is obviously electrical and I would have thought that the Lexus people would have had more immediate access to electrical diagrams and parts.

I think we should be offering John every encouragement on his chosen path. Hindsight is indeed wonderful.

I have sold the Po-40 Folding Mirror Kit to many countries and many enthusiasts of varying ability. I have helped many mis-connected installations and so far, have a 100% success rate getting the installation to work. I have yet to see a single Po-40 control box that has failed.

[toffee_pie]

If it was my car i would not take it to lexus, unless you got very deep pockets or bargain a good deal with them.

of course i hope he gets a good outcome, im just voicing my own thoughts.

[johnatg]

Thanks for the inputs, guys.

Just to establish my own credentials, in the past 45 years I have only twice taken my own car to a garage etc - that was for a couple of clutches when I didn't have the time. So I have a lot of experience of fixing stuff - I once succesfully repaired the wiring in the dashboard of a Mazda 626 after an electrical fire (caused by some previous owner mumpty having bypassed the fuse protecting the rear fog light - I traced that problem to chafed wiring in the boot). And I can tell you - I can well understand why wiring fires can write a car off - it took me ages to replace every wire. But that was extremely simples compared with the Lexus.

I spent quite a lot of time trying to find what is wrong with the Lexus - it was a hard decision to seek help. I have no experience at all of finding a good auto electrician and anyway there's actually not much they can do that I can't. The Lexus wiring is extraordinarily complicated and I figured (maybe naiively) that a dealer was the best place to turn to. We shall see - eventually.

Meanwhile the PO-40 will shortly be on its way back to Michael - he's going to get it checked by his techs. But it's been working fine for months (and was working again after the first junction box replacement) and I have no reason to suspect it or its connections.

Watch this space!