Instrument lighting problem

[CaptainKcorb]

A buddy with a K750 (I'm an oilhead guy) has no instrument lights though the neutral light, hibeam indicator, etc. work fine. He's tired of not being able to tell how fast he's going at night so we're digging into it next week.

 

Any words of wisdom here on likely causes other than fuses (checked) and broken bulbs (they're all out)? Also, any pointers on removing the half fairing would be helpful as the manual is a masterpiece of Teutonic brevity.

 

As always, thanks in advance for any assistance.

[RFW]

It seems prudent to take the instrument cluster off first, remove the back and check the lights before getting too carried away with this. I imagine the K75's cluster comes off with the same 4 allen bolts as my K100RT does since the instruments are the same. It takes about 5 minutes to remove the 4 bolts underneath (they are a bit awkward, but not really bad) then undo the single screw that holds the connector cover in place then unplug the 2 connectors.

 

Once that is done the entire cluster can be taken to the bench and all small screws in the back removed (do NOT remove the larger countersunk phillips screws). The back will now remove. Be careful with the big sealing O-Ring.

 

After that, the bulbs are accessible. Be careful when handling the FPC (flexible printed circuit) inside.

 

If the bulbs are OK, then you'll have to do some troubleshooting with the help of the wiring diagram in the owners manual. The diagram, by the way, is really excellent.

[k75duck]

What you need to do to access the bolts holding the instrument cluster varies by model of K75. On a K75RT, you can access them withhout having to remove any fairing parts. On a K75S, you'll probably need to remove the windscreen and the one of the fairing side panels.

 

Then remove the four 5mm Allen bolts securing the instrument cluster. Then either a Phillips screw or 3mm Allen bolt to detach the wiring harness connector.

 

Once off, place the cluster upside down on a towel to protect it and remove the nine Phillips screws around the perimeter.

 

When putting the little black bulb holders in make sure the "foil" contacts on each side have not folded under themselves. This probably won't make sense when you read it but will when you have the thing apart.

[CaptainKcorb]

Thanks Gents,

 

Once again, helpful advice received and appreciated. Good to know that the fairing likely doesn't have to come off, at least not completely.

 

Does anyone know of a resource that details the pinout of the connector to the instrument panel?

 

Best regards to all,

[breyfogle]

Thanks Gents,

.... Good to know that the fairing likely doesn't have to come off, at least not completely.

 

It may be possible but it will be faster to remove the fairing panels (radiator screen -> windshield -> left & right turn signal lenses -> left & right side panels)

[CaptainKcorb]

Thanks Breyfogle, good to know the order of disassembly.

 

Cheers,

[JerryMather]

I need to change the bulbs on my KRS too. I only have one out but when I dig into it ..... I'll change all of them so I don't have to get in there again. It looks like a pain to do this.

[ESokoloff]

Jerry, I wonder if you could find a LED replacement here?

[JerryMather]

Interesting ........ didn't think about those, thanks for the link.

[ESokoloff]

If you do end up replacing with LED's could you post info on them?

TIA

[CaptainKcorb]

Well, my K75S riding buddy came by Tuesday and we've solved his problem, and probably a LOT cheaper than a visit to BMW.

 

The problem turned out to be inside the instrument pod, but all the bulbs were good. We were amused by the little green sheaths around the light bulbs, but they do allow for an easy change of colour.

 

Once the pod was on the bench, and the back off, lightly running a finger down the two rows of protruding connector pins revealed that three of them were loose, and the rest firm. Carefully lifting up the rubber membrane showed that the firm ones were bonded to the mylar circuit board, and the three loose ones had come free.

 

Not wanting to take the soldering iron to the mylar unless necessary, we made some very small washers out of thin cardboard and pushed one down to the base of each of the loose pins, thinking that this would force the pins down more firmly to the mylar once all was reassembled, and restore the connections.

 

It worked. We'll see how long it lasts but I wouldn't be surprised to see it last the life of the bike given the pressure from the pod back and screw down connector cover. I have no idea what the mylar circuit costs but I don't imagine it's cheap. If this fails we'll try the soldering approach, or better, a conductive adhesive (we thought of JB Weld but didn't know if it conducts once set).

 

Another note from the repair is that the fancy nut retainer holding the 6mm fairing bolt at the left side of the tank failed, making it more than frustrating to reattach. A proper repair would be to weld the nut directly to the U shaped rubber holder, but we made do with nut and lockwasher. BMW should make this a welded assembly as it's cheaper, lighter and more durable.

 

Anyway, checking the connector pins and packing them down may solve other instrument electrical issues without expensive parts replacement so I thought some would like to know how this turned out. I wish I'd thought of taking a picture or two but that bulb turned on after all was back together.

 

Safe riding....