Jon Evans

The replacement bulbs have arrived, I'm planning to try them out on Saturday.

People have been predicting the death of DIY car repairs for the last 30 years. Any new technology seems to trigger this - engine management computers, fuel injection, ABS brakes, airbags, OBD etc. In practise, there will always be independent garages servicing cars, and therefore there will always be tools and spare parts available to non-dealers. Also you'll always get amateur enthusiasts (like us) who will work out for themselves how to fix common and not so common faults with their vehicles. Another thing to remember is that computers have actually made cars a whole lot more reliable than they used to be. It might be expensive to replace a whole ECU, but actually the percentage of cars requiring ECU repair must be microscopic. My Mk 4 LS400 is full of computers but the only common faults I'm aware of with the electronics are the display backlights and the illuminated needles in the dashboard gauges. By "common" I mean that you see the odd post about them here, on a forum populated by enthusiast drivers of this particular model. Again the instance of this fault compared to the actual number of LS400s produced must be tiny. In short, I don't think you need to worry. Go and buy yourself that nice new LS!

You might have seen this from the other thread where I posted it, but I've been having a go at fixing the temperature display illumination in my Mk4 1998 LS400 today. I've put together a blog post about it. If you want any specific photos taking then let me know, because I've got to take it all apart again when the new bulbs arrive.

I've uploaded all my photos to a blog post about this repair. I'll also post this link to the other thread.

Well you can't usually drop in an LED for a bulb. You change the brightness of a bulb by changing the voltage, but LED brightness is best controlled by modulating them. i.e. turn them on and off many times per second, and the brightness depends on the ratio of on time to off time. On for 1ms and off for 1ms = 50% ratio, so 50% brightness. Also you have to be careful not to pass too much current through an LED, it drastically shortens their life expectancy. I measured the voltage across the temperature bulb terminals, it was 8.3v bright and 5.3v dim. You'd need a resistor to drop that 8.3v down to something like the 3.2v max VF for the LED. A 160 ohm resistor would do it. It might work, I'll give it a try. I've got bucket loads of clear 3mm LEDs. I'll solder a 160 ohm resistor to one of them and test it in the dark on the way home from work tomorrow. Even if it works, it will be quite awkward to fit an LED and a resistor in the space where the original bulb went.

The centre display has two bulbs, the outside displays have one each. They are all surface mount 3mm bulbs, after intensive googling I've concluded that in the era of the LED nobody makes SMD incandescent bulbs any more. I've ordered some small green bulbs from CPC, I'll test them on the wire I've left sticking out of the dash before I fit them. I bought enough to replace all of the bulbs, I still haven't decided whether to do that or not. It will mean all locations have exactly the same brightness and colour, but on the downside it'll be a bit of a faff to do.

OK, everything is reassembled and working now. With the engine running I measure 8.3v when the brightness is high, 5.3v when low. I think they are almost certainly 12v bulbs, underpowered to make them last longer. There are several stockists of 12v 3mm "grain of wheat" bulbs on eBay, I think I'll try those first.

In fact now it's all reassembled I wish I'd also removed one of the working bulbs so I can compare the brightness. Ah well.

OK, I have formulated a plan. I have managed to desolder the two broken bulbs, it wasn't as awkward as I thought. I just applied a bit of heat while prying the bulb with a small screwdriver. I've reassembled the console but before doing that I soldered a couple of wires to the place where one of the bulbs was. This is so I can measure the voltage when it's back in the car, and also experiment a bit with other bulbs / LEDs before opening it all up again to replace them properly.

I've got it in bits now. They are bulbs unfortunately. Very hard to replace. Do you know where I can get them from? They are 3mm PCB mounting bulbs. 17 for display and switch illumination, with green rubber covers. One without the cover, to illuminate the passenger seatbelt warning light. They do use PCB surface-mount LEDs to light the indicators in the switches, and in most cases they're doubled up too. 3 LEDs for the "Dual" indicator, and 2 each for the Front, Rear, Recirculate, Fresh Air, Auto and Auto indicators. I've attached a work in progress photo. I've taken a lot more, which I'll upload in another post when I've finished. I had to do a lot of dismantling to get access to the bulbs. It looks like the only sensible way to replace the bulbs under the LCD displays is to cut them off the PCB. If you wanted to do a nice desoldering job I think you'd have to desolder the displays as well, which means 16 pins each for the temperature displays, and 25 pins for the centre display. As it's a double sided PCB this will be extremely hard to do without destroying the LCDs. Jon

I want to remove the centre console of my LS400 to put new LEDs in the temperature displays. I seem to remember last time I tried to disconnect the car battery the alarm kept going off, and in the end I gave up. Is there a special trick to it? Put the key in the ignition first, or something? Thanks Jon

I had similar* symptoms with my 1998 LS and it turned out to be a loose battery connection. The garage didn't tighten it enough when they serviced it. You say you've already cleaned and tightened the battery terminals, so maybe the problem is further down the wires. I used to own a BMW 735 and they used to get loose / corroded connections on the fusible link (like a very high amp fuse in the engine compartment). Maybe a similar problem with your LS? * single click when I tried to start the car, and the whole car went dead. Then after about 10 seconds the lights started to come on again and the dashboard "rebooted" itself. Jon

Not much of an answer, but I guess you could try putting something over the sensor so that it thinks it's pitch black. It's one of the black plastic circles on the top of the dash near the bottom of the screen. I believe one of them is used for the illumination sensing, the other is used by the aircon to make it slightly cooler in the full glare of sun. Jon

Hi Rod, I've got the same model and year, but mine is green with beige leather. I've had it over 4 years now and I still love it. Yours looks really nice. My engine bay was as clean as yours once, after a full valet just after I bought it. :) My driver's / passenger's temperature displays have both lost their LED illumination. The driver's one only went last month. At some point I'm going to fix it, when I do I'll post pictures here. My wheels are Lexus originals and are a real mess, with all the lacquer peeling off. I'll get them refurbished at some point. Yours aren't to my taste to be honest but I'd still take yours over mine! As others have said, the box under the passenger seat should contain a first aid kit. Mine was pretty much all there but I replaced some of it with the contents of a cheap kit I bought at Aldi. The only expensive work I've had done on mine since I bought it was a new timing belt / water pump / idler pulley etc., which cost something like £850 all in about 2 years ago. Has yours got the sat nav centre console? Well done on your purchase Jon

The subject reminded me of this HA HA HA HA HA!!! (probably showing my age...)

How about getting in touch with a reporter at your local paper? Local papers love stories like that. Also if they published something it might cause other locals to report the same experience, which might make it more likely that something gets done about it.

My dad has used Ric Wood for years, since the days when he had the industrial unit next to where my dad worked. He's a really good chap & *really* knows cars, as you'll see from his site. http://www.ricwood.com/ Worth phoning for a quote.

If you go to Crucial.com they have a very good system for telling you what the possible memory permutations are for your PC. Crucial are also pretty good value, and deliver really quick. Hit that link and go to the Memory Advisor section of the page.

It sounds like the interlock which stops you shifting out of Park unless the brake pedal is pressed -- but you said you were already out of Park. Try putting it in Park with the engine running, and pressing the brake pedal a few times, to see if it's the same noise.

Now you tell me! :-)

I couldn't resist trying it - and it works! Thanks Redsteve, saved for future reference. Jon

I'm going to have a go this weekend. Thanks for the advice.

Any tips on cleaning the rubber strips where the windows emerge from the doors? Mine are a bit green and mossy. :-) I've got an LS400, the front door ones are kind of accessible because the windows go all the way down into the doors, so you can at least get a cloth onto the inside of the rubber. The rear doors look a bit more tricky though because the window gets in the way of doing a proper job because it only goes half way down. Thanks

I just found this out while playing around. On the LS400 Mk 4, if you hold down the recirculation button while turning the ignition on, the screen displays an adjuster for "SMOG" which presumably adjusts the sensitivity of the automatic recirculation system.

I asked a dealer and they wanted to remove the console of my car and send it away for unlocking. I didn't even ask how much that was going to cost! I hacked the code out of mine manually - to read about the adventure, go here: http://evansweb.info/articles/2007/04/18/forty-two-seventy Summary: if you go to the "change code" screen, it starts by asking you what the current code is, and if you get it wrong it just asks you again. So, occasionally at lunchtimes I've been going to the car and entering security codes in blocks of 100, which takes about 5 minutes.