The LCD on my message centre/odometer display isn't illuminating. I've changed the bulbs that provide back lighting but still nothing. The messages/mileage is displaying as I can barely make it out at night with lights on.

Any suggestions as to what the underlying problem is?

Do you get power to the bulb holders?

Mine was like that but need bulbs solved it.

Maybe also check continuity in the bulbs to make sure they're good. If they all blew instantly it would point to an electrical fault somewhere.

Are the rest of the panel lights coming on? You haven't turned the brightness down to nothing have you?

I've replaced the bulbs with new ones though the old ones looked OK. Instruments illuminate as they should and warning lights too.

I’m with Gilbert, the dimmer is on top of l/h arm, on top as such, you can rock it either way, if there was no illumination you wouldn’t see anything

The other thing you can try if you don't mind taking the cluster out again, is to turn the bulbs slightly. They twist in (as you must know having changed the bulbs) but the ends of the tracks can get tarnished. So if you twist them in then back them off a touch so the contacts are bearing on a clean area of the track, that might do the trick. Otherwise you could be looking at a break in the track feeding them. I've got a spare scrap cluster, I'll have a look at it and see if I can see where the track could have broken.

Agree on track, and bulb holder if its in one, tarnish being a likely cause. Over various vehicles I reckon cleaning up was needed about half the time to get a new bulb going. You'd have thought that if the old one made good contact for ages until it blew a new one would just slot in and go. But Mr Gremlin says "No.".

These days I clean things every time however good they look.

Clive

I've tried cleaning the bulbs and have also swapped them for known good bulbs/holders. and still no dice. i'm suspecting the wiring between the dash and the BECM.

This thread reminded me so I've just dug out my spare instrument cluster and had a look. The track to the bulbs are coming from a three legged beasty marked on the board as FT6. Markings on it appear to be K1484 and Google gives me nothing on that. However, a 2SK1484 is a switching N channel MOSFET which would make sense and is probably what allows the dimming. I would suspect a dead MOSFET in all honesty, the reason the panel is spare is because one of the multi channel MOSFET chips that illuminates the various warning lamps (seat belt, alternator, oil pressure, etc) is dead so none of the warnings were working. So if one can go, then I'm sure others can too.

Is it repairable?

More than likely.

Either replacing the MOSFET, or swapping the mileage chip onto another cluster PCB so you don't lose that would work to sort it out.

I have another cluster. How hard is it to swap the mileage chip or replace the MOSFET for that matter?

Easiest option is to keep your gauges and mileage chip but replace the whole PCB. With the cluster out break the seals on the top of the plastic cover on the back, unclip the locating tabs all around and remove that (you'll need to unplug the wires to the sounder). There's a peg fixing in the centre which just pops out if you pull the cover off. Disconnect the ribbon cable that goes to the separate board that is standing up from the other one by lifting the edges of the IDC connector, to take the pressure off, don't just try pulling the ribbon or you'll break it. It is this board that stores your mileage information so as long as you don't turn the ignition on while the cluster is out, you won't have a problem with that. Undo the 9 screws holding the circuit board to the back of each gauge (3 on each gauge) and lift the whole PCB off. Fit the PCB from your donor cluster, being careful not to trap the ribbon cable from the other board, and refit the screws. Reconnect the ribbon, put the back on (remembering to reconnect the plug for the sounder) and that's it, job done. If you've got a spare cluster, you can take that one apart first and see how it comes to bits before you remove the one from your car.

You may find that the gauges read slightly differently, that is what the 6 trimmer pots along the top of the circuit board do, they allow you to calibrate the gauges. My ex-police car has a calibrated speedo that is spot on accurate but I contacted the company that calibrated it for plod and they told me which pot does what if you want to be really anal. Normally the speedo reads slightly fast so an indicated 70 mph is an actual 65 mph but on mine what it says you are doing is what you are actually doing.....

Thanks, sounds reasonably simple.

Swapping the whole board will swap the mileage chip too... It's soldered to the main PCB.

Either you need to desolder/remove the mileage chip, or the faulty MOSFET and swap them over... Either swapping the MOSFET off the spare board onto the original one, or swapping your mileage chip off the bad board to the replacement one and then refitting that to the gauges..

If you swap the whole board without swapping the mileage chips then you risk adding unwanted mileage to your vehicle, which would then require a trip to me to reset them both :(

Martyuk wrote:

Swapping the whole board will swap the mileage chip too... It's soldered to the main PCB

I didn't think it was as I had to swap the board on mine. Although the spare cluster wouldn't have had as many miles on it as on mine (I don't think anyone has as many miles on as mine!) so maybe I had to sync it with the BeCM and update my mileage, I honestly don't remember. So, if you have more miles on than on the spare cluster, it will be OK, otherwise it might be safer to get the soldering iron out and swap the MOSFET and hope that is the problem.

Yeah, if cluster has lower mileage than BECM you will get ODOMETER ERROR and if you resync it, the cluster will update to the higher BECM mileage.

If the cluster has higher mileage, then it will automatically update the BECM with no warning when the ignition is turned on.

You've got to ask yourself how much you care about the exact mileage on a 20-year-old 200k+ vehicle though ;-) I know mine's about 4000 miles low after I repaired the faulty dashboard.

I suppose it all depends on the actual mileages. If the car has done 120k and the cluster has done 200k then you wouldn't want to add that sort of mileage to it. If the other way round the dash can be updated to match the BeCM but if there's not a lot of difference, then I agree, I won't be that important.

Best bet if you want to play it safe is take photos of the old and new cluster just in case it comes up later on. Only really a concern if you had say an insurance claim or similar and it had covered far greater mileage than you would normally do.