1997 Ls400 Instrument Cluster Illumination Problem.

[steve2006]

One of the problems with the car is the instrument panel lights up for a second when the ignition key is turned then blanks out completely so I started work on the cheap Toyota Celsior this evening and after finally working out how the cluster came out set about on the kitchen table to see if I could diagnose the problem.

After removing the white plastic cover over the main board I could immediately see a burnt area on the board, after carefully cleaning with some IPA ( no not the beer) it could be seen that the area was close to the invertor which generates the high voltages need to light up the cluster which would explain the fault present.

There were no signs of liquid damage and the board is encased in the plastic cover so how this has happened I'm not sure, it could be a one off or signs of things to come with this cluster.

What I intend doing is to cut away the 2 tracks that run through this area and then solder jumper leads to bypass the damage.

I will take the board with me to work tomorrow and do this.

Once the repair is completed I will post the results good or bad.

[Ruud]

That is quite a burn. Looks almost as if someone has left his burning cigar on there :)

I reckon bypassing the 2 will do the trick. Using phone cable is quite handy for this. (not the extremely thin ones)

[steve2006]

Yes luckily there is no print in the area on the component side of the board, as for the phone cable I have a roll in the garage and as you say it is ideal for this type of repair, I will of course use the best matching colour!

I have quite a bit of paperwork with the car and from this it looks like the cluster has been like this for several years as the MOTs state the mileage was not readable and the fact the board has burnt all the way through would seem to confirm it is a long term problem.

I was going to cut out the affected area but it runs quite close to a fine cluster of tracks but providing it is isolated it shouldn't be a problem leaving it.

Also sussed out the boot opening tonight there is another button on the alarm fob you press momentarily and presto boot opens!

The two keys I received I think are both valet keys so only work in the ignition lock, that's not a problem with the remote release but I may in time get another lock with matching key from a scrapyard.

[Ruud]

Yes luckily there is no print in the area on the component side of the board, as for the phone cable I have a roll in the garage and as you say it is ideal for this type of repair, I will of course use the best matching colour!

Of course. You can then add that to your list of extras.

JDM Toyota Celsior with Teas Maid,4 bulbs in the front indicator units nicer one piece headlights and a UCF20 engine cover - JDM Toyota Celsior 2 with hi-tech phone cables in dash.

[ROYT]

Might be worth drilling a hole near the burn, in the vain hope a bit of ventilation might keep it cooler..

[beavisrules]

burns could be , high voltage arcing across broken tracks or to nearby tracks , high current due to failed component (coils or capacitors goning short).

I think a combination of both most likely , but nothing to loose by patching the wires and gamble.

It'll be easier to just get a replacement then start doing component diagnostics.

I'd test it out of vehical if possible and watch it carefuly!

[Ploddo]

That is quite a burn. Looks almost as if someone has left his burning cigar on there :) I reckon bypassing the 2 will do the trick. Using phone cable is quite handy for this. (not the extremely thin ones)

^{2 mmaste keys 1 sub & 1 valetkey}

[steve2006]

That is quite a burn. Looks almost as if someone has left his burning cigar on there :) I reckon bypassing the 2 will do the trick. Using phone cable is quite handy for this. (not the extremely thin ones)

^{2 mmaste keys 1 sub & 1 valetkey}

Hello,

You've lost me?

Is that what I should have?

I have 2 valet keys I think, 1 unknown key with Toyota logo on it that doesn't fit anything ( the blade is completely different and won't even go in any lock) and a smaller all metal key that may be the alarm override key.

Sorted the boot remote opening thank you for the phone message.

[Parrot of Doom]

Looks to me as though something else has failed and electricity has arced across that gap. Simply repairing those tracks might not solve the problem.

[ambermarine]

One of the problems with the car is the instrument panel lights up for a second when the ignition key is turned then blanks out completely so I started work on the cheap Toyota Celsior this evening and after finally working out how the cluster came out set about on the kitchen table to see if I could diagnose the problem.

After removing the white plastic cover over the main board I could immediately see a burnt area on the board, after carefully cleaning with some IPA ( no not the beer) it could be seen that the area was close to the invertor which generates the high voltages need to light up the cluster which would explain the fault present.

There were no signs of liquid damage and the board is encased in the plastic cover so how this has happened I'm not sure, it could be a one off or signs of things to come with this cluster.

What I intend doing is to cut away the 2 tracks that run through this area and then solder jumper leads to bypass the damage.

I will take the board with me to work tomorrow and do this.

Once the repair is completed I will post the results good or bad.

Hi Steve

Looking at the board and the area that is damaged this seems to be a circuit layer between the two that are on each side of the board it is in actual fact a sandwich pcb and the short as occured between curcuit running elsewhere on the board.

Without the circuit diagram and some very sophisticated equipment you are unlikely to resolve this problem and are more likely to make it worse ,we are not talking simple electric curcuits here we are talking complicated electronics.

As someone as already suggested ;a replacement board is probably the best solution

[steve2006]

Yes it is double sided print on the board but there is no print in the same area on the opposite side.

I did the bridging and cut back of the track to isolate the damage but on testing the fault still remains as before, needles light up for a second then die.

I have also noticed that the backlighting is also not coming on so it obviously has other problems.

Been trying to source a replacement but no luck at present.

Seperate question but if anyone has a 1997 LS400 could they confirm the front seats have side airbags fitted as mine has but I thought thiese were only present on the series IV model, it could be a JDM thing.

[willskoda]

Mine's a 96 if that's any good - no side airbags

[ambermarine]

Yes it is double sided print on the board but there is no print in the same area on the opposite side.

I did the bridging and cut back of the track to isolate the damage but on testing the fault still remains as before, needles light up for a second then die.

I have also noticed that the backlighting is also not coming on so it obviously has other problems.

Been trying to source a replacement but no luck at present.

Seperate question but if anyone has a 1997 LS400 could they confirm the front seats have side airbags fitted as mine has but I thought thiese were only present on the series IV model, it could be a JDM thing.

Hi Steve, it looks like a capacitor as died on the invertor circuit and will be fixable with the right engineer but that is likely to be someone working out of a small shop in Japan were these things are fixed quite often .

Good luck in finding a board.

[BaxfromNZ]

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.

[Bluesman]

That's a serious burn out and I wouldn't be surprised if other components have gone down, its also worrying that the burn is next to a transformer.

Good luck with it, Mike

[steve2006]

Cheers Mike.

At the time of the post there were no clusters at a reasonable price on Fleabay ( now they is a glut of course) and with the other work needed to bring the car back to a reasonable level of repair, including replacing a dog eaten interior, I decided to break the car up.

Didn't get to the bottom of the cluster fault but haven't heard of another case yet.