R1100RS electrical voodoo/abs fault

[mgordon]

Just bought a 1994 R1100RS and rode it up from LA to Vancouver. After a new swingarm axle and tuneup, the bike runs like new (only 38k miles). HOWEVER, the bike had been hotwired--ignition switch torn out and wires bundled through the hazard switch.

I bought and installed a new ignition switch, and found a wiring harness in SF, from which i cut and soldered in the other plug end (from the fram wiring to the ignition switch). The bike ran, but then i found out that the ignition switch loom connector to the frame connector wasn't wired up right either. I've resoldered everything (now my parking light works too!). However, the ABS top light flashes when i put the relay back in. I found both front and rear sensors had been cut and re-attached, so i resoldered those too!

I also found that the kill switch wiring-to-connector (where it plugs to frame) was totally mickey-mouse twisted together. So i resoldered all the wires together (i'll have to get a new kill switch + wiring).

My last resort re: ABS is that i jiggled the wires up behind the top flashing abs light in the tell-tale display, which made it go off. When i start the bike, the relay clicks too. Maybe i'm just shorting out the abs display light.

If anyone has ANY clue, please help! The only thing i can see from the wiring diagram is that the ABS is wired through the oil pressure light, but my idiot display doesn't have one! It only has two voltage (battery) indicators??

Oh, and also pulled the abs diagnostic plug, wired the center pin to ground for 8 seconds while holding down the abs switch and turning on the bike. The light went out, but started flashing again as soon as i started riding.

[MCMXCIVRS]

Wow, with so many cut wires and such it could be any number of problems. What the heck happened to this bike?

I think the first step would be to determine if there is a fault code set in the ABS computer, then try and track it down from that. It is odd that only the top light flashes, you should have both flashing alternatly when the ABS faults. There may be more wiring problems yet. Does the bottom light flash at all? The bulb may be out in it if not. It may even just be something as simple as the sensor air gap being wrong.

[bmwmick]

If only the top lamp comes on, I would suggest tracing 12V where it is supplied to the ABS Unit. Pin #15 at the ABS connector on the side of the Hydro Pump or pin #30 on the ABS warning relay in the relay box.
See here: http://www.ibmwr.org/r-tech/oilheads/ABS-II_low_voltage_modification/index.shtml

Ed:
The sensors don't come into play until AFTER the unit is initially powered up. They could cause a fault during wheel movement but not before unless they are totally disconnected. With my ABS modification, only the top lamp comes on solid until the Alternator is putting out enough current to pick the relay I added.
After that, it appears normal with both lamps flashing in unison.

[mgordon]

Hi Ed, yup, loads of problems. As i said, the bike had been stolen and hotwired. Perhaps the ABS sensors were cut because of the fault flash--wouldn't surprise me, with the way everything else was cobbled together. I hooked up an LED sensor in line with the middle diagnostic plug and it flashed 8 times, which indicates the sensor air gap. Apparently, the air gap was (increased) to 4.5-5.5mm in 1997 for all models, plus i didn't check at the widest point with the paint dot on the sensor wheel. I probably just need shims, and maybe a bulb in the display.

i found out also that two charging lights is normal for this bike. wierd

[mgordon]

The bottom ABS bulb was missing. I stuck one in and both lights flash now. bottom one stays on if i push the abs button.

I'm assuming because of flash code (8) that i need to check and re-shim the sensors--probably not enough of an air gap!

[bmwmick]

The bottom ABS bulb was missing. I stuck one in and both lights flash now. bottom one stays on if i push the abs button.

I'm assuming because of flash code (8) that i need to check and re-shim the sensors--probably not enough of an air gap!

Do they flash in unison?

[mgordon]

no, alternating. If i push the button, the bottom one stays on.

[mgordon]

well, the abs fault suddenly cleared today, at least temporarily. If i start and ride, then switch the ignition (key) off and on while the bike is rolling, the lights come on together, and go out and the ABS works! Must be a voltage or sensor issue, if it happens while moving?

[bmwmick]

well, the abs fault suddenly cleared today, at least temporarily. If i start and ride, then switch the ignition (key) off and on while the bike is rolling, the lights come on together, and go out and the ABS works! Must be a voltage or sensor issue, if it happens while moving?

You probably have a marginal battery. Read this.....
http://www.ibmwr.org/r-tech/oilheads/ABS-II_low_voltage_modification/index.shtml

[mgordon]

Yup, saw that. The PO said they put in a new Gel battery. Tested at resting voltage 12V+, and 14v charging, though that's not a load test for sure.

[bmwmick]

Yup, saw that. The PO said they put in a new Gel battery. Tested at resting voltage 12V+, and 14v charging, though that's not a load test for sure.

Yes,
It's the cranking amps that matters most.

[mgordon]

The PO put in a Universal Battery UB12180. Doesn't say cranking amps, just 18amp hours. But the bike had been sitting for six months, so maybe it just needs a trickle charge. UB says this is the replacement for BMW sealed battery, as it's gel lead sealed.

[bmwmick]

The PO put in a Universal Battery UB12180. Doesn't say cranking amps, just 18amp hours. But the bike had been sitting for six months, so maybe it just needs a trickle charge. UB says this is the replacement for BMW sealed battery, as it's gel lead sealed.

M,
It's an AGM SLA battery not GEL. That is a good thing.
It's not quite upto the AH rating that BMW requests (19AH) but it will probably work for a while. Lot of folks get away with the little Odyssey 16AH pc680 battery for several years.

[mgordon]

Ok, the battery is up to charge, and shows over 10v when cranking (14.4 when running, 12.9v at rest) which should be enough for ABS self-check? I read that it needs 9.5v or higher when starting/cranking to clear the ABS check.

I've disconnected the battery and fuse #5 to reset the ECU. The one curious thing is that with the ignition on, the fuel pump runs continuously, as opposed to stopping after 'priming' the pressure for a few seconds. Is this normal? If not, the hacked wiring may be the culprit, and the continuous fuel pump tripping up the ABS check at ignition, until i roll the bike a bit and re-start. Maybe i just need the OEM BMW gel battery with 19AH?

[mgordon]

Anyone?

[bmwmick]

Anyone?

No,
it's not normal and stay away from the GEL. :)

[mgordon]

Thanks, Mick. I've looked at the fuel pump circuit, and not sure what to do. I'm going to be putting in an OEM right side switch + wiring (current one is all spliced, from it being hotwired/stolen, and/or from putting on bar bax--did my best to re-solder, but that could be the culprit!). Is the fuel pump relay part of kill/start circuit? What shuts it off, the relay?

[bmwmick]

Thanks, Mick. I've looked at the fuel pump circuit, and not sure what to do. I'm going to be putting in an OEM right side switch + wiring (current one is all spliced, from it being hotwired/stolen, and/or from putting on bar bax--did my best to re-solder, but that could be the culprit!). Is the fuel pump relay part of kill/start circuit? What shuts it off, the relay?


The relay has 12V on the control circuit any time the ignition is on. The ground for the relay coil is controlled by the Motronic unit.

[pmdave]

I don't know whether this applies or not:

With the ABS on my K1, turning on the ignition with the ABS sensor unplugged caused a fault. (ABS lights flashing)

I took the machine to the BMW dealer, and the mechanic plugged in his computer and did a procedure that reset the system.

If your oilhead ABS works the same way, it could be that the fault was caused by activating the ignition with the sensor wires not connected properly.

As noted, the high-zoot brakes need a minimum voltage to function, so if the battery is not up to that voltage at startup, the system will fault. I was riding an R1150RT in New Zealand with a marginal battery, and the brakes faulted about every other morning.

I was also told that you're not supposed to start the bike with the brakes applied. (a bit of a sticky wicket when the bike is parked on a hill)

pmdave

[mgordon]

Dave--the PO had cut the ABS sensor wires, so i think you've sorted it out! I tried grounding the diagnostic plug, pin #2 to clear the fault, also unhooking battery, but indeed maybe a diagnostic computer needs to reset? It is certainly not the stock battery, and 18ah vs 19ah, and hasn't been load tested. Still, the fuel pump runs continuously and when the key is turned, power is on, even if kill switch is off, so i have some wiring to trace (it was hotwired, and i replaced the ignition switch, but the wiring/frame harness had been cut/spliced at the other end). Thanks. Maybe a trip to the shop after all.

Re: fuel pump--i see that the fuel pump relay runs through the sidestand switch circuit, and...the PO or thief had cut that too, shorting the wires together (to get the bike to start). I wonder if that would keep the FP running continuous with power on?

[lawman]

I had similar symptoms on my 1100RT; the lights flashed and the abs was very slow to come on line, even after several attempts to reset it; additionally, the clock worked erratically; a new gel battery solved both problems; no problems for over a year now; hope this helps; good luck..wj

[mgordon]

this bike had apparently been sitting for six months, and there is so much hacked wiring on it, plus terrible general maintenance, it's safe to assume that a new (OEM) battery would be a wise purchase. Thanks

[kbasa]

If you've got lots of hacked wiring, it might be worth buying a harness and just replacing it all. I think Beemer Boneyard has used ones.

[mgordon]

Dave, I've got a used harness. Problem is that some of the hacked wiring is going to the frame, not from the harness--IE killswitch, ignition, etc. Lots of it could be re-soldered, like the abs sensor wires. Some has to be replaced, like the sidestand switch. I'm keeping the harness for splicing in connectors from the frame end. So far, i've only needed the ignition-frame connector x2 (to connect to ignition switch pigtail, and then connect again to wiring harness).

Any thoughts on the fuel pump running continuously? Before i spend big bucks on a new battery, it seems that might be the culprit in ABS fault, ie voltage drop at crank. Also, not good for the fuel pump to be running constant without crank....

[mgordon]

After a lot of troubleshooting and consultation, i think i have it. The ABS resets if i roll the bike, ignition off, and then turn on. In other words, it won't self-check unless it's getting a signal from the sensors BEFORE the bike is started. If it was a voltage issue (ie weak battery) it would be an issue from rolling as well.

So, i think that the ABS needs to be reset by a computer. I've unhooked the battery, and that didn't do it. I've also grounded the diagnostic plug. The fuel pump is a separate issue, and i think once i put a replacement sidestand switch in, it will resolve.

[AntonLargiader]

The fuel pump is a separate issue, and i think once i put a replacement sidestand switch in, it will resolve.
I doubt it. The sidestand switch might keep it from running but won't cause it to run. The FP relay is activated by being grounded by the Motronic (as Mick said). So either something has been hacked in that circuit, or the Motronic is leaving that pin grounded for some reason. We have a bike at the shop where this has happened; so far I think it's a bad Motronic but we'll see.

[mgordon]

Anton, the man himself! So, could the fuel pump relay itself be grounding out, or maybe the Motronic connector? How does one diagnose this?

Does the ABS thing sound right? Thanks!

[AntonLargiader]

So, could the fuel pump relay itself be grounding out, or maybe the Motronic connector? How does one diagnose this?
It could be anything on that bike. You need to look at a wiring diagram, figure out what's supposed to be grounded and what's supposed to be hot, when they are supposed to be whatever, and start poking around with a voltmeter. You will be able to find the cause of the FP running, I guarantee it!

Does the ABS thing sound right? Thanks!
Not really, but I can't follow your description that well. Everything I know about ABS is on my website (and on IBMWR).

[mgordon]

Thanks, Anton.

[mgordon]

You're going to love this: i pulled the fuel pump fuse #6, fuel pump still running. I pulled the heated grips fuse #7, fp stops. So they hotwired the fuel pump into the heated grips switch to get it running. Geezus. Not to mention they put a 15a fuse in the heated grip slot which is a 4a fuse. So where is the heated grip switch connector? My guess, under the tank.....which is not bolted on, so that's a clue. Help please to follow thru on my detective work....

[mgordon]

Is the heated handgrips connector under the tank?

[AntonLargiader]

I think the plug for that is on one of the front subframe spars. Odd place to try to jumper the fuel pump to.

[mgordon]

Ok, after much spilled fuel, cursing, and properly soldered wires, i pulled the tank--the fuel pump sender connector + wiring was correct, but taped together. The only conclusion i had left was the fusebox. And, lo and behold, i can see black tape on a wire leading to Fuse 7--which has a switched/hot lead from the ignition. Looks like they wired the fuel pump relay to fuse 7, and disconnected the heated hand grip circuit that was supposed to be there, as there is NO power to the hand grip connector.

Question now is, again after much cursing, how do i get inside the fusebox? Help please...do i have to remove the rear wheel and pull the box out?

[AntonLargiader]

There are small screws which hold the upper and lower halves together.

[mgordon]

Yes, but then how does the upper half come out? There's not enough clearance. Thx.

[mgordon]

Fixed! What a PITA getting the fuse box apart. Anyway, as i suspected, fuel pump relay was wired in to Fuse 7. Works properly now, at least not running all the time. Not sure the outcome on ABS, but better for the bike.

[mgordon]

For anyone interested, i had the battery load-tested, it's fine. So, it's an abs brain fault.

[mgordon]

Got the bike to the BMW shop, and re-set the ABS, works great now!!!!

[Andy VH]

I don't know the exact voltage levels for the ABS. But, I fried my ABS modulator, according to my dealer, because I did too many cold morning/low voltage starts and it burned in a permanent low voltage code to the ABS. I got eight years of service out of the orignial Mareg battery. Only three out of the expensive Westo (Panasonic really) replacement battery. The ABS lights would flash alternately, which should have been my clue to a pending problem.

Last year, I luckily found a replacement ABS modulator on an Ebay Buy It Now for $250. I grabbed it up! Installation was easy, to me anyway. After installation and brake bleeding I took the bike to my local dealer. The service manager had to reset the modulator to identify with my bike (the modulator came off a K1100RS) and now everything works great!

By the way, my second replacement battery is a Toyo (Panasonic copy) from China that I got from Brieter Battery, shipped direct to my house for $39! Its on a third riding season and working great.