Starter motor failed, why would disconnecting it lose all lighting?

[RSavage]

1999 1150GS + ABS

Starter motor failed on the Welsh Rally yesterday. The symptoms suggested that it was sticking because of the high temperatures as, in the early part of the saga, it would operate if I left the bike to completely cool.

However, it did eventually fail thus:

Stop the engine. Attempt to re-start causes the ignition, oil pressure, ABS and neutral lights to dim almost to extinction. Starter motor quite hot so wait ages for the bike to cool. In the meantime connect jump leads from another bike to help my poor battery.

Notice that the solenoid and starter motor are still warm even though the engine is cooling. A bit more thought and investigation suggests that the solenoid is going short circuit to earth. Disconnect the switched output from the solenoid (the short braid to the starter itself) to take the load off the battery. Solenoid and starter cool. Good! One new starter motor please.

However, once we had managed to push start the bike we found that none of the lights worked except for the RID illumination and the stop light nor did the horn. Don't know about the heated grips.


Any thoughts? Please!! I'm supposed to be in Germany in 7 days!!!

TIA

Richard

 

[D6]

have you got a new starter on it yet?is it still the same?

 

[RSavage]

No new starter motor (yet). The bike is on a recovery truck en route from North Wales as I write.

 

[davegs]

Starter

Sounds like the relay welded it's self together weather dosen't overheat the starter motor used mine many times in 100 deg plus (death vally) this is why it got hot. Lights dont work cos battery flat. Possibly cooked the starter moteor as well, don't connect new motor to the existing relay or you'll have two u/s motors.
dave gs.

 

[D6]

was gonna tell u same thing, its down to earth through motor cos of relay

 

[RSavage]

Sounds like the relay welded it's self together weather dosen't overheat the starter motor used mine many times in 100 deg plus (death vally) this is why it got hot. Lights dont work cos battery flat. Possibly cooked the starter moteor as well, don't connect new motor to the existing relay or you'll have two u/s motors.
dave gs.

Hi Dave

Do you mean starter solenoid piggy backed onto the starter motor or the relay in the fuse box? I don't think that the starter solenoid is welded 'on' because I would expect the motor to be spinning continuously in that situation, unless there is a fault also with the stud switch in the solenoid. I can hear the fuse box relay engaging and disengaging when I press the start button but I cannot hear (or feel) any action in the solenoid. Battery isn't flat AFAIK as the lights etc were working fine until I disconnected the connection from the solenoid to the starter motor. Also the stop light still works and as that is an LED unit I would expect it to fail to operate long before a filament bulb stopped glimmering.

My money is on a faulty solenoid but I'm very puzzled about the lights.

Richard

 

[cookie]

is there more than one wire on the starter live stud?

 

[RSavage]

is there more than one wire on the starter live stud?

Yes, but only on the i/p stud i.e. that which is still connected to battery +ve .

That is what is sooo puzzling.

I only disconnected the o/p from the solenoid.

 

[davegs]

Lights

Leds take a fraction of the current used by filament lamps and will work on a little battery. The starter wont turn if is in gear and you've probably run
the battery down too low anyway. I would take it to a specialist or BM dealer
before you spend too much cash on spec. I was refering ot the relay on top of the motor.

 

[RSavage]

Leds take a fraction of the current used by filament lamps and will work on a little battery. The starter wont turn if is in gear and you've probably run
the battery down too low anyway. I would take it to a specialist or BM dealer
before you spend too much cash on spec. I was refering ot the relay on top of the motor.

Indeed, but I was thinking that LEDs are more voltage dependent than filament.

We did try connecting the other battery straight to the starter motor to see (a) if the motor would spin unheeded and (b) if it was in mesh. (a) = Y (b) = N.

I agree that it is all speculation until the bike arrives and I can extract the starter motor. Also I will take it to Brian Giles down in Pembury ASAP.

Cheers

Richard

 

[davegs]

Starter

Brian will sort it ok couldent rember his mane.
Good luck.

 

[RSavage]

Brian will sort it ok couldent rember his mane.
Good luck.

Absolutely. Does he service your bike? My only problem is getting it to him as I cannot push start the bike.

Bike has now arrived and I have had a close look at things.

Update on the lights. When we were trying to jump start it in Wales I disconnected both the solenoid to starter braid and the switched feed from the starter relay to the solenoid. I don't fully understand it but it appears that the load shedding relay requires this connection to be present before it functions correctly, viz re-attaching the feed enables the lights etc to function (I didn't test the horn as it's a bit late). That would make sort of sense as the lights extinguish ISTR if you start the engine while they are on.

A direct feed from the battery to the solenoid switch produces nothing. So I'm pretty certain that the solenoid is U/S.

Also the starter will spin when also fed direct from the battery but the bearings sound very dry, although this maybe because it is spinning 'out of mesh'.

Any thoughts on whether to replace the entire starter motor and solenoid with a new unit from Motorworks at £180 or one of their exchange recon units at slightly less? Or just the starter solenoid? My gut feeling is to go for the whole new unit.

Also can anyone give me any tips on removing the starter motor, e.g. how may bolts there are, where they are and their torque setting? I can see 2 cap screws, I think.

Richard

 

[turnipbmw]

glad you posted this - I really wanted to push your bike into the Village hall and have a look, sounds like a like an interesting fault

 

[davegs]

Starter motor

Only two allen bolts, one behind the motor quite easy once the plastic cover removed, disconnect the battery first.
Dave gs.

 

[RSavage]

New (complete) Velo starter ordered from Sherlocks on Monday, fitted Tuesday PM. Bike starts.

Starter motor clutch was almost solid.

Load shedding relay uses the solenoid to provide an earth path, which explains the lack of lights if you disconnect the switched supply to the solenoid.

Richard