Howplum

The replacement head unit has arrived, and apparently the 2 DIN adaptor should be here next week. In the meantime I have been studying the wiring and noticed there is a dedicated RCA input for a reversing camera, which must be better than my present wireless version. There is also a wire to be connected to the reversing light circuit so that the screen automatically comes on when reverse is selected, but it would be a lot easier to splice into the appropriate wire from the reversing light switch under the centre console, although it's location is not immediately obvious without some serious dismantling of the gear selector assembly. I've had a look on my electronic repair manual but there is no mention of the switch that I can find. Because the new head unit has both USB and 3.5mm inputs I decided the modify the centre console by removing the ashtray assembly and fabricating a plastic panel, into which I fitted a charger socket, twin USB charger socket and a dedicated USB/3.5mm socket for the stereo - i hope it works when it is all connected up. I've also been labelling the wiring so that I make up a couple of ISO adaptors:

You could consider chrome spraying. I had my gold LS400 badges done and they turned out well. I used this company: https://invictaspraychrome.co.uk/ Other companies are available!

They look good. I wonder though if you might get black marks on the driver's side where your heel rests.

I have now bought a used 2 DIN Pioneer touchscreen head unit off eBay, model MVH-A200VBT: https://www.caraudiocentre.co.uk/product_m-pioneer-mvh-a200vbt_p-40737.htm Whilst awaiting delivery, I'm trying to figure out the wiring and how best to connect the existing harness to the ISO connectors on the new unit. No proprietary adaptor harness is available so I therefore have several questions before embarking on yet another learning curve! 1. There are currently three wires that connect the radio/player to the antenna and its relay, marked ANT+, ANTA and ANTB. The antenna is designed to only rise when the radio (tuner) is on, but since the replacement unit only has the one wire (blue) my quandary is to which connection to use. I read on a US forum that connecting to all three seems to work, but is that right? On other setups the antenna usually only rises when the unit is switched on, regardless of which function is being used, although perhaps a separate switch could be fitted if desired. This the wiring diagram from the US Repair Manual I have: 2. Should I include the existing amplifier? This is less work from a splicing point of view because it utilises the existing wiring. However, my concern is that the new head unit produces 50W for each of the 4 channels, but I can find no information on the output of the original system*, so I wonder if the speakers can handle a more powerful setup, if that is indeed the case. So far I have found that having the volume at 30% or less is perfectly adequate, because the car is so quiet. *After some more digging it seems the outputs of the amplifier are 40W front, 30W rear and 55W woofer. On a US forum mention is made of the Nakamichi door speakers being rated at 20W/40W, but that may be a red herring. 3. There is currently a wire marked AMP+ from the head unit to the amplifier, but I'm not sure what it does. Does it just provide power to the amplifier when the head unit is switched on? 4. The woofer on the rear shelf receives its signal from the amplifier only, not the head unit, so if I opt to bypass the amplifier I will need to use the woofer connections on the back of the new head unit. 5. There are three connections on the existing Pioneer unit marked SGRD1, SGRD2 and SGRD3 which apparently are Speaker ground wires, so presumably/hopefully these can be spliced together. These are my schematics of the existing radio/player connectors: Any advice or observations would be appreciated.

I have now ordered a Metra 95-8153 double din adaptor from the US because it doesn't seem to be available in the UK, despite the website I found stating they had 100 in stock!

Hopefully no deeper than the existing unit. I would probably choose "mechless" anyway, which tend to take up less room.

Replacement capacitor fitted but the unit is still dead, so time for a rethink. I could get yet another used unit, but that would also be 25 years old, so could also potentially have issues in the future. All I use it for is listening to the radio, preferably via 4G or DAB+, or my own music, which is on both iPod or USB stick. This is why I was trying to add an auxiliary socket. Telephone connectivity is not important. The idea of a 2 din unit, possibly with a touch screen, appeals, especially if Google Maps can be displayed from my phone. Perhaps best to avoid the unbranded £45 ones on eBay though! I think the makes to look at are Pioneer, JVC, Sony, Kenwood and Alpine. Something to research over the festive season.

Thanks George, that's useful to know. I'll fit the replacement capacitor when it arrives and see what happens. Another option is to completely update the head unit and fit a double din unit of some sort, although connecting it to the existing harness, especially the amplifier, might be challenging. No doubt I will lose the CD changer facility though. https://thebassbin.co.uk/product/autoleads-dfp-25-03-lexus-ls400-double-din-fascia-panel-adaptor/

Thanks for the offer Stuart, I will bear it in mind. In the meantime, it occurred to me it might (hopefully) be something simple, starting with the on/off switch. One push of the button should presumably close the circuit, turning the unit on, the next push opening the circuit, thus turning it off. This is the back of the POWER-VOL assembly in situ: And these are the connection markings: I assumed the middle three connections related exclusively to volume control, so by default the two outer ones are for the power supply. Using the resistance facility of my digital multimeter on the prongs, with the assembly installed, it looks as though the circuit between the two outer connections is permanently open (no resistance reading). It is only closed (resistance reading 0.00) when the button is held in, which doesn't seem right. Also, there is no click indicating that the internal switch is locked in place, which I'm sure there used to be/should be. Am I barking up the wrong tree?

As a diversion I came across this option for installing a replacement double din unit: https://www.clublexus.com/forums/ls-1st-and-2nd-gen-1990-2000/857222-1995-1997-ls400-aftermarket-radio-install-utilizing-stock-amplifier-for-pioneer-radio.html It's American, so the wiring will be different colours, but hopefully the pin numbers will be the same. Obviously, the CD multi-changer becomes redundant and is subject to finding a housing adapter to fit, which might be a challenge because most seem to be for pre 1994 models. Ideally a single din would suffice, but finding a housing might be be even more challenging.

I assumed it was leaking so have removed it and ordered a replacement. Bu**er. So perhaps it was the two bent prongs, but since the fascia is connected to the lower PCB, which is where the power comes in, I have no other idea for the apparent complete loss of power.

I checked the connections and confirmed the unit was receiving power, both switched and unswitched, so the problem isn't the fuses. So, I dismantled the radio, yet again, but a bit further this time, and discovered this leaking electrolytic capacitor on the lower main circuit board: I can only assume it's an unfortunate coincidence, since it's nowhere near where I was soldering. The other minor issue I noticed was two of the prongs that connect the lower board to the upper board were slightly bent, so perhaps they weren't making proper contact. They were easily straightened, but obviously great care is need on reassembly. It's out with the soldering iron again!

The cable was twin core speaker wire, but is much too thick for the job, in my humble opinion. I have some silicone (or maybe it's rubber) covered wire which is much thinner and more flexible, so I'll make up a new connection once I get the unit working.

Thanks. I do a few checks when I have time.

Is it possible there's a security code? The unit has been out of the car for several days.

It turned out that three of the micro bulbs were not working. Firstly I removed the faulty bulbs by gently levering them off the board. Notice the pads of solder. The next step was to replace the bulb in the holder. This is fiddly, but the wires have to be straightened so that the bulb can just be pulled out. Replacement is the reverse of this process, although the wires, which hold the bulb inside the plastic holder, will have to trimmed to fit. After that is just(!) a case of soldering the bulbs back onto the board. Unfortunately I can't test my handiwork because the audio unit doesn't work at all now, as mentioned in my other topic about adding an auxiliary socket.

I made up a lead from a couple of lengths of speaker wire with female RCA phono sockets on one end. Red is right and black is white. Then I drilled a hole in the casing in such a way that the upper cover could be removed without disturbing the leads. Then I soldered the other ends of the red leads to the TUR and TUL connections. The two black leads I attached to a chassis tab, although they were reluctant to stay in place at first. Not pretty, but hopefully effective. At the same time I replaced the three micro bulbs in the fascia, which was REALLY fiddly, although I have covered this in a separate topic. All back together again. However, the problem I have now is that having reinstalled the complete audio and climate control assembly back in the car the audio unit does not power up, which is very frustrating. Either there is something I have missed or I have damaged a vital component somehow. Any ideas anyone?

As Paul says, you might need to prove your case for an increased offer from the insurers, including the service history and details of any work done above and beyond any service requirements. Did the seller give you a wad of paperwork with the car, because that would help prove it has been looked after properly? Hopefully the MoT history speaks for itself. Insurers used to use Glass's Guide, but I'm not sure that would still be relevant for a 15 year old car. Any details of optional extras fitted will also help. Perhaps you could check on a car buying website to get a worst case scenario. In any event, you will probably have to wait a few weeks in case the car is recovered.

I dismantled the radio this afternoon so here are some pictures: This is the standard Pioneer audio unit fitted to my 1996 model. The two waveband buttons (top left) are different to those shown in the post by "kebin", but hopefully this won't make any difference to the modification. The display is starting to deteriorate, but I'll live with that for the time being. This is after removing the top cover, which is held on by just a few screws. Next I removed the front fascia, which is held on by two screws and two clips on each side. The power/volume knob has to be removed first. Strictly speaking this doesn't need removing before removing the upper PCB, but I have three of the micro bulbs to replace. Next I removed the upper PCB, which has no physical attachments other than the black multipin connector on the right, so a firm upward tug will release it. Hopefully reassembly will be equally straightforward. Turning the PCB over I was relieved to find that the TUL, TUR, AML and AMR connections were exactly as per "kebin"'s post, so it's looking promising so far. However, I didn't realise they would be so small - they looked bigger in the pictures! I have marked them with a red pen. That's it for the moment. I'm waiting for a magnifying glass on a stand to arrive to that I can do some soldering. Stuart, on the tape player I can see the drive belt and in theory it should be replaceable, given the attention to detail so far, but without delving deeper I cannot say for sure. Mine works so I'm leaving it well alone!

All will be revealed in due course. Watch this space.

Thanks again Mark, but that's the post number 766 by "Kebin" I referred to in my post yesterday. What appeals to me is that it looks like a fairly straightforward and is also on a non-US spec. car, so hopefully mine will look the same when I open it up. Who listens to AM anyway? If it works then the OCD in me would like to re-letter the AM button, but perhaps that's a step too far! Some of the (US) alternatives mentioned seem fairly complicated and occasionally unsuccessful.

Thanks for that link Mark, very interesting. It looks as though there is more than one way to achieve the same result, i.e. a hard wired 3.5mm input, especially for an expert. I see that ground loop isolators are plentiful and cheap, but first things first, to see if my unit can be modified successfully.

Stuart, I don't think the cassette assembly needs to be touched, although the phrase "Remove the upper AM/FM circuit board from the radio" might be economically worded! We'll see. I have got some bulbs on order, which is another issue, together with some female RCA phono connectors, so once they arrive later in the week I'll dismantle the radio (again!) and let you know how I get on. I'll take a few pictures along the way. This is very much uncharted waters for me, although I dismantled the instrument cluster more times than I can remember.

Having done a bit more digging on the internet I came across this post on a US forum: https://us.lexusownersclub.com/forums/topic/35241-hooked-ipod-to-stock-stereo/ The post I particularly like is the last one by Kevin in 2017 where he has wired the auxiliary wires direct to the radio PCB in such a way that the AM button becomes the auxiliary selector. However, whilst I can use a soldering iron, I would appreciate any observations from those amongst you who know more about electronics than I do. It's a little difficult to see exactly how/what he has soldered to the TUL and TUR connections, but am I correct in assuming they would be the respective wires going to the centre posts on the female RCA phono plugs I plan to use, the negative (outer) wires being soldered to the chassis?

I had another look at the procedure for adding an auxiliary input shown in the link in my original post, which involved hard wiring, as opposed to some sort of adaptor. Originally I thought that doing this sacrificed the CD player, but I now realise that by using 5 pin relays, as opposed to 4 pins, it doesn't. It becomes a switchable alternative source. My knowledge of electrics is pretty basic, but it looked perfectly feasible, with care. However, the wiring colours and the connector plug are for US specification cars, as is the electronic repair manual I have, none of which agree with what is actually on my car, which has the original Pioneer head unit. I established that the grey connector to the amplifier is for the CD changer by the simple process of systematically unplugging the connectors to see what didn't work. Although there are 14 slots in the connector, only 6 are used, and they are: Top row (L - R): 1 - Green/black 2 - Green/red (or brown?) 4 - Brown/yellow 5- Brown/white Bottom row (L - R): 12 - Green 13 - Purple It's possible that 1 & 2 and 4 & 5 are paired, due to the colouring of the wires, but I'm hoping someone on here has access to the correct (non - US) wiring diagram and can tell me the specific assignation of each of these wires. What I need to know is the speaker channels, i.e. R+, R-, L+ and L-. Many thanks.