Help, No Spark with K1100LT

[105462]

I put new brushes in my starter and replaced it but now have no spark to the plugs. The starter turns the motor over very well. It ran well before I did the work. Am I going to have to take it to a dealer and have them hook it up to their Computer? Don't know what to do. Any suggestions. :banghead :dunno

[PUDGYPAINTGUY]

I put new brushes in my starter and replaced it but now have no spark to the plugs. The starter turns the motor over very well. It ran well before I did the work. Am I going to have to take it to a dealer and have them hook it up to their Computer? Don't know what to do. Any suggestions. :banghead :dunno


Did you accidentally knock any wires off while you had your hands in, or are all the connections back on the solenoid etc?

[Bobmws]

Go back and look at everything you touched to get the starter out, see what you didn't reconnect. Coil wire? Is the plug to the computer snapped in tight?

[105462]

Bobmws, Yes Everything is as it should be. I went back 3 times and checked everything out. I even sprayed all the contacts :hungover at the connecters. I am not new at this as I have had K bikes apart several times. It is just a mystery so I guess I will have to have it put on the Diagnostic machine by a dealer. Something must have blew, like the Hall sender or the other electronic senders maybe. When I find it I will report what it was. :banghead

[bmwmick]

Bobmws, Yes Everything is as it should be. I went back 3 times and checked everything out. I even sprayed all the contacts :hungover at the connecters. I am not new at this as I have had K bikes apart several times. It is just a mystery so I guess I will have to have it put on the Diagnostic machine by a dealer. Something must have blew, like the Hall sender or the other electronic senders maybe. When I find it I will report what it was. :banghead

Bill,
What year K1100LT? There is an ignition amplifier on the early ones (up to 07/1993 I think) and if it goes out, no spark is a symptom. It mounts on the front side of the battery box right near the starter. Stan Smith at Rocky Point cycles can supply a spare/replacement module (Transpo BM325) for about $25 instead of the $145 or so from dealers. If it's a 1993, give me the last 7 digits of your VIN.

HTH,

[105462]

bmwmick,
Sounds like you are on to something. It is a 93 last 7 of VIN is 0300174. I know it does have that plug in divice on the front of the battery box as I had to unplug it to remove the battery box when I took the starter out. I did clean the contacts and made sure that it was plugged in tight.I did have the ground wire loose on the bottom of the Battery box the first time I tried to start it but after I fixed that it still won't send spark. Could I have screwed it up by tring to start it with a loose ground on the bottom of the box?
Thanks for your help I will be waiting your reply.
Bill

[bmwmick]

Bill,
You have an earlier K1100 than I do. :) Yours is a 02/1992 manufacture date and you definitely have the amp. http://tinyurl.com/ast2o RealOEM is a good reference place for part numbers, bookmark it.
Item #17 here: http://www.realoem.com/bmw/showparts.do?model=0536&mospid=47926&btnr=12_0770&hg=12&fg=05
is the amplifier. I do NOT think it's possible that you fried it by cranking with no ground. Here are the pinouts for that module: http://195.125.241.148/cgi-win/product.exe?BM325
The Motronic unit actually processes the Hall sensor pulses and then fires the coils via that amp. These modules are generally pretty tough. Have you unplugged the amplifier and plugged it back in? Cocked connector?

UPDATE: I just went out to the garage and measured my spare module. Pin #4 supplies the ground that is switched by the module to fire the coils. So that means the ground wire to the battery box is not used. There is no connection from the module mounts/heat sink to the internals of the module.
Check your sidestand switch. Does the fuel pump run for about 2 seconds when you turn the ignition on? If not, you have an interlock problem. These bikes (unlike the later models) will crank all day with the sidestand down but will not fire. :(

[105462]

BMWMICK,
Thanks much for your help. I will order the Spark Amplifer and try it. It's worth a $25. gamble. The side stand switch is O.K. & the fuel pump runs a few seconds when the Key is turned on. If you can think of any :dunno thing else let me know.
Bill :brow

[bmwmick]

BMWMICK,
Thanks much for your help. I will order the Spark Amplifer and try it. It's worth a $25. gamble. The side stand switch is O.K. & the fuel pump runs a few seconds when the Key is turned on. If you can think of any :dunno thing else let me know.
Bill :brow

I agree, it's nice to have one as a spare. If you're handy with a meter, you could look for 12V on the green wires to the coils (pins 15a)(a hat pin held by an aligator clip is a nice easy way to probe the wires, it makes a very small self-healing hole in the insulation if you can't get on the connector easily). They 'should' be powered any time the ignition is on and the interlocks are made. All the Motronic does is switch the other side of the coils to ground to make sparks. Front-most coil is for Cyls 1&4, rear one for Cyls 2&3 but they both get 12V all the time. There are ways to test the Hall sensors too but I doubt that is your problem since it happened in the garage.
I grew up in your area, if I was still there I'd just ride over with my diagrams and a meter. :bottle

Good luck!

[105462]

bmwmick,
I took readings from the coil wires with the key on and I am getting 11 volts to the front coil and 10 volts to the rear coil. Does this make sense or is there somthing wrong with those readings. I get a full 12 volts at the battery with the same meter. The battery needs charged as I do get 12.5 to 13 with a fully charged battery. :dunno
Bill

[bmwmick]

bmwmick,
I took readings from the coil wires with the key on and I am getting 11 volts to the front coil and 10 volts to the rear coil. Does this make sense or is there somthing wrong with those readings. I get a full 12 volts at the battery with the same meter. The battery needs charged as I do get 12.5 to 13 with a fully charged battery. :dunno
Bill

Bill,
Both coils are fed 12V by the same wire further up the harness. If you are measuring voltage with the coils still connected, it could be that the amplifier is shorted internally and supplying ground to both coils ALL the time instead of being switched, as should normally happen during cranking. Do the coils seem to be getting warm? I would probably probe the (-) side of the coils while cranking to see if they dip towards ground while cranking. That would indicate that the amplifier is actually switching as it should. (This will be easier with an analog meter rather than a digital as you can watch the needle wiggle a lot easier than seeing a digital display changing) Remember, the coils only create a spark after the ground side is first Grounded (via the Amp) to let the coil Charge and when the ground is removed, Spark happens.
If you disconnect the small coil primary connectors, both pin 15a (the green wires) should measure about the same as battery voltage when the ignition is on. There WILL be a little loss through the ignition switch and harness.
If you measure the (-) side of the coil connectors with an Ohmmeter, do they have continuity to ground all the time? That would indicate a shorted amplifier module to me.

[PUDGYPAINTGUY]

These bikes (unlike the later models) will crank all day with the sidestand down but will not fire. :([/QUOTE]


Sorry for the trivia hijack although I found this out on a ferry this summer with my GS...major embarassment.

[CustomSarge]

An LED w/1000 ohm resistor in series is Real Handy when looking for short pulses. Also, an analog meter has a tolerance to back EMF spikes coming off the coils' low, switched side, that might toast a digital.

If I only had a digital, I'd look across the coil contacts in the harness, with them all disconnected, and spin the starter to check for switching. That may take a resistor (100-10k) as a pullup to substitute for the coil, though.

I learned about the FYR K1100 ign amp when building my '93 LTX. I'm spinning it over and No spark (!?). In the Clymer it showed the amp, but all I saw was an open connector (DUH). $75 later, it ran great (still does). Good Hunting... <<<)))

[105462]

bmwmick,
I tested the coil wires with an Ohm meter and have ground on all four wires ALL the time with the key off. With the key is on I get Voltage to the green ones but NO Drop or pulse switching while cranking. The side stand switch is working and the gas pump works for a second or two when the key is turned on. Remember that I said that all I did to the bike was put new brushes in the starter. COULD there be something wrong in the load shed part of the starter grounding out the coils when cranking??? But then would that cause the constant grounding of the coil wires when the key is off?
Thanks a million to all you guys who are helping me with this. :clap
Bill

[bmwmick]

bmwmick,
I tested the coil wires with an Ohm meter and have ground on all four wires ALL the time with the key off. With the key is on I get Voltage to the green ones but NO Drop or pulse switching while cranking. The side stand switch is working and the gas pump works for a second or two when the key is turned on. Remember that I said that all I did to the bike was put new brushes in the starter. COULD there be something wrong in the load shed part of the starter grounding out the coils when cranking??? But then would that cause the constant grounding of the coil wires when the key is off?
Thanks a million to all you guys who are helping me with this. :clap
Bill

Bill I sent you a private message, check your PM's at the top of the screen.

With the ignition off, I would expect the 12V (green) wires to be grounded. This is what BMW does with the ignition switches. Confused me the first time I saw it too. It keeps static pulses out of the system.

If the Amp side of those coil connectors are always grounded, the Amp is probably dead. You could measure the Amp. Pin#4 is ground and should be an Open to pin #1 and pin #6 normally. If pins 4,1,6 are all shorted together, the Amp is toast (this is on the Amp itself with the harness disconnected and the coil connectors disconnected).

I doubt the brushes have anything to do with your failure. These bikes don't use the starter brushes to ground the load shed relay like the earlier K-Bikes.

[kioolt]

The load shed relay does not turn off your ignition, fuel injection, or fuel pump even on the earlier K-bikes. That is one bit of false information that the internet has started about the early k-bikes. A bad ground through the starter on early k bikes will turn off the load shed relay which will cause the headlight, heated grips, and radio to not work but the bike will still run if you can get the engine started by bump starting.

[105462]

BMWMICK,

When checking pins for ground , would I be checking the male pins on the plug or the female pins on the part that is bolted to the battery box???
Bill

[bmwmick]

BMWMICK,

When checking pins for ground , would I be checking the male pins on the plug or the female pins on the part that is bolted to the battery box???
Bill

Bill,
Is this a trick question? :laugh You will be checking the Male pins on the module bolted to the battery box.

[105462]

bmwmick,
Woops Sorry I had them reversed but you got the Idea.
Thanks Bill

[105462]

bmwmick,
I took the Module off and tested it. Pin 4 grounds out to every pin but 3 & 5 and they are of course unused pins. It does not ground out to the back plate of the module. I assume that it is toast??? :dunno
Bill

[bmwmick]

bmwmick,
I took the Module off and tested it. Pin 4 grounds out to every pin but 3 & 5 and they are of course unused pins. It does not ground out to the back plate of the module. I assume that it is toast??? :dunno
Bill

Bill,
That is how they fail. Sounds like yours is a paper weight. :deal
Get in touch with Stan Smith http://www.rockypointcycle.com/ and tell
him you need a Transpo BM-325 Ignition Module. It may take a little longer to get it because he normally only stocks Airhead parts.

[105462]

BMWMICK,
Thanks , I will get a replacement and let you know what happens.
Bill

[bmwmick]

BMWMICK,
Thanks , I will get a replacement and let you know what happens.
Bill

Bill,
Echlin also sells a replacement but I think it's almost as valuable as the genuine BMW part. Echlin TP392.

[bmwmick]

BMWMICK,
Thanks , I will get a replacement and let you know what happens.
Bill

Bill,
Any progress?

[boofer]

:lurk :bottle

[BubbaZanetti]

:jose :lurk :lurk


and i think K bikes suck! :) (just a little YB humor)

i got very interested last week in the "vacuum pressure" submissions for that K75 on ibmwr mailing list.............