SR ROLLA Posted August 6, 2015 Share Posted August 6, 2015 While I have my dash out I have replaced the extremely dim old bulbs with new LEDs. It appears that part of the dimness issue was also that quite a few of the bulbs weren't working at all. When I test fitted it to check the new lights it's much brighter but some of them still don't work. The LEDs are polarised, so I have tried them both ways in their bulb holders. Also the twist in bulb holder can be inserted 2 ways as well but no combination of positions seems to work. LEDs which work in one of the working sockets don't work when I swap them into one of the non working sockets and vice versa. The circuit board appears in good condition, so I'm stumped as to why they don't work. Would it have to be a fault somewhere in the wiring of the big, multi-pin plug which brings power to all of these lights? Or is there something else I'm missing? This is not my area of expertise at all, so any suggestions would be a big help. Cheers Crappy pics for reference: Quote Link to comment Share on other sites More sharing options...
Bangbug Posted August 6, 2015 Share Posted August 6, 2015 I have this same problem. But when I run power directly it works. It's a relay or something that isnt working and I haven't traced yet. Try putting power onto traces with bulbs in to rule out any failures Quote Link to comment Share on other sites More sharing options...
Seedy Al Posted August 6, 2015 Share Posted August 6, 2015 maybe try using an ohm meter to check continuty on all the terminals Quote Link to comment Share on other sites More sharing options...
downtrail Posted August 7, 2015 Share Posted August 7, 2015 Are you just replacing the back lighting or the warning lamps or all of them? Quote Link to comment Share on other sites More sharing options...
Frosty Posted August 7, 2015 Share Posted August 7, 2015 The printed curcit sheet will have dirty connection pads. At the point where the contact for the bulb holder sits against the circut sheet there is a section of the copper track that has no sealer on it. Use some very fine sandpaper or a steelo pad to clean that small bit of the track then put a smear of grease to stop it reoxidsing again, refit bulbs and test. This is very common and was something we saw a great deal when servicing the BMC's. Was happening on cars as new as 5 years old if in a damp inviroment. Good luck. 3 Quote Link to comment Share on other sites More sharing options...
SR ROLLA Posted August 7, 2015 Author Share Posted August 7, 2015 Sweet, good tip. I'll try cleaning them up this weekend, re fit and see how we go. Quote Link to comment Share on other sites More sharing options...
Threeonthetree Posted August 7, 2015 Share Posted August 7, 2015 There will also be a difference in resistance that the the new LED lamps have compared to the old incandescent lamps. Often this will mean that some relays/flasher units will not make or break contact (ie work) due to the lack of resistance in the load. I have LED-erized an older dash before and wired in some resistors in order for it all to operate properly. Try what Frosty has said but if you still have issues, my money is on the resistance. 2 Quote Link to comment Share on other sites More sharing options...
Frosty Posted August 7, 2015 Share Posted August 7, 2015 Bad contact points add resistance, that's why even the old bulbs where dim. Quote Link to comment Share on other sites More sharing options...
SR ROLLA Posted August 11, 2015 Author Share Posted August 11, 2015 So, cleaned up all the connections on the circuit board with superfine sandpaper and re-tested. The lights all come on now, yay! Except for 2, boo. I have gauges, door open light, hand brake on light but nothing from the top 2 corners. Working from the back of the gauges, so I can see when they light up, I tried swapping the bulbs around, different bulbs, turning the holders around… nothing works. They don't come on with parks, headlights, high beams, nothing. Have another look back at the front of the cluster… they're the bulbs for the indicators. Facepalm, I'm officially retarded. So good news, right? everything goes now, right? In daylight I properly refitted the whole dash, speedo cable, all the switches, cigarette lighter etc and TA DAH! None of the gauge lights work. Fuck. The indicators, door open, hand brake etc lights all still go, but nothing for the dials. I found a blown fuse (for the taillights, which apparently also covers the gauge lights), swapped it out and my gauges have life! …except not the petrol gauge or the central light between speedo and tacho. So I'll run out of petrol driving at night and I can only see low speeds and high revs. I guess I'll have to pull it out again and see what's going on. 1 Quote Link to comment Share on other sites More sharing options...
ajg193 Posted August 11, 2015 Share Posted August 11, 2015 I once had an issue where the oil pressure and voltage gauge back lights didn't work on my AE92. Then one day my overhead lamp short circuited and melted a wire/blew a fuse (was a while ago, it might not have blown a fuse actually). Ever since that day my oil pressure and voltage gauge back lights worked perfectly. /Look for something stupid like a blown bulb somewhere else in the car. You may even find that the two lights that aren't working are on some different circuit like HEATER or RADIO. 1 Quote Link to comment Share on other sites More sharing options...
SR ROLLA Posted August 11, 2015 Author Share Posted August 11, 2015 Cool, good idea. I'll check that out before pulling everything apart again. Would be nice if it was an easy win. Quote Link to comment Share on other sites More sharing options...
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