BaxfromNZ

Fred81: Lexus will have them, they just will not readily release them because they would rather sell a new part but the age of the car is such that the likelihood of someone being prepared to pay a couple of thousand for a new part is fast diminishing as the value of the car drops. Malc: Thanks for the suggestion I may follow that up but I suspect that whoever tries to fix it now is definitely going to need the PC board diagram as the experts over here have tried all of the obvious things (I hope!). Steve 2006: You are right; if I knew who the instrument cluster manufacturer was I would go straight to them and I think I would have more chance of getting one that way. If I run out of options I may contact you about sourcing one over there - thank you for the offer. Incidentally I suspect the engine manufacturer for these cars is Yamaha not Toyota and I wouldn't mind betting the the Yamaha V8 four stroke outboard motor probably looks remarkably like a Lexus V8 motor!

You can't find them second hand here in NZ otherwise that is exactly what I would do. My only option then is to fix the one I have got.

My instrument cluster has gone dead. Initially it was intermittent but now it is permanent. This is the last model LS400 with variable valve timing prior to the LS430 so the instruments include a trip computer which my previous 1996 LS400 did not have. Several kind people have sent me wiring diagrams but what I need is the circuit diagram of the actual printed circuit boards inside the cluster as the cluster is currently at an instrument repair shop and they have hit a brick wall. There is a main board and one or two daughter boards in the cluster one of which is the power supply circuit board and this is where I suspect the fault might be. If you have access to a diagram or know where I can source one I would really appreciate it. I have replaced all of the electrolytic capacitors on the main board myself but this did not fix the problem. I appreciate that Toyota do not normally release this information because they would prefer to sell me a new one but there are some clever people amongst you who may have managed to wheedle one out of the strongroom somehow! Read more: http://www.clublexus.com/forums/ls400/745617-1998-ls400-instrument-cluster-circuit-diagram-urgently-needed.html#ixzz34O7LGXgM

Hmmm, capacitors pack up in the instrument panel too from what I hear.

Iain, Your illumination problem might be affected by the light dimmer potentiometer. A cheap fix is to flood it with CRC or similar - I know this used to work on volume control pots on transistor radios when they got scratchy and made the volume hard to adjust so it should work on the dimmer pot if that is indeed the problem. Try to get the CRC inside the pot if you can. It is more likely though that the capacitors in your intrument cluster need replacing. Regards, Ian.

Hi Steve, that burn mark is a weird one. I have been researching this topic for several days as my 97 LS400 has a similar problem and it is fairly common with these cars. The impression I get is that the capacitors on the board pack up and the solution is to replace them with industrial quality capacitors. I believe there are about 6 or 7 main ones. I am about to have that done to mine so will let you know how I get on.