ABS Lights 2004 R1150RTP

Greetings,

I bought my 2004 R1159RTP from a police auction with ~35k miles. I stripped out 10 lbs of police wiring, and much to my surprise it started right up! (I feared I would remove something crucial and would brick the entire bike.) It seems to have been well maintained.

This summer, after sitting in the garage over another long Montana winter, I am having ABS problems.

I am a right below-the-knee amputee (BKA), and rarely operate the rear brake with my heel(!). (The ABS system is a savior for BKA. . . makes it much safer than my old Honda 900C.) I threw a set of knobbies on this baby and ride dirt with it. I have tipped over only a few times, always to the side with the prosthesis.

The machine passes the ABS system self-check and the rolling test. . . all the lights are out. As long as braking is very light, all is ok and braking is clearly power-assist. As soon as a bit heavier braking action is invoked, the ABS light flashes quickly and the light below the ABS (general warning light?) comes on. The system appropriately reverts to non-ABS. I have grown accustomed to the increased brake force required, but have lost the simultaneous rear braking action .

Any suggestions for troubleshooting?

Are battery connections tight, and or is it time for a new battery? Weak batteries and ABS don't work well together.
DP

DennyPink said:

Are battery connections tight, and or is it time for a new battery? Weak batteries and ABS don't work well together.
DP

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Thanks for the reply. I saw threads about electrical issues being a root cause. I haven't checked, but I have not observed other indicators of battery problems. Worth warming up the meter and ruling that out.

BMW No. 34 1 581

Somewhere, I saw a link to an Ebay store that sells an after-market version of the BMW No. 34 1 581 funnel used for filling/bleeding the iABS system. Now I can't find it! Any suggestions on how to find that Ebay listing? All of my search ideas have failed.

electrode said:

Somewhere, I saw a link to an Ebay store that sells an after-market version of the BMW No. 34 1 581 funnel used for filling/bleeding the iABS system. Now I can't find it! Any suggestions on how to find that Ebay listing? All of my search ideas have failed.

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Beemer Boneyard.

Not FleaBay, but - beemerboneyard.com and put funnel into the search box.

BC, you've got quick fingers!

Pauls1150 said:

BC, you've got quick fingers!

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Nah, just good timing.

Pauls1150 said:

Not FleaBay, but - beemerboneyard.com and put funnel into the search box.

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THAT'S IT! Thanks for the reference to the boneyard, Paul.

You're very welcome! And enter "bmwmoa" into the little box for a 10% discount.

Interesting. I'm having the exact same problem. Battery is only a year old and has been on a proper SLA float charger for the winter. Only the rear brake circuit is giving me grief. I'm replacing the rear pads and doing a rear circuit flush and bleed this weekend and will post my observations in this thread.

Aaaand... no joy. Still getting '17433 Pressure in rear wheel circuit to (sic) low'. The module appears to be toast. Oddly, the GS-911 also reports module voltage as 9.8 Volts but measured right at the connector with DVM is approx. 12.8V. All other parameters in the green.

I'm considering my options.

When you say you measured at the connector, do you mean the one at the ABS control unit? Which pin?

Per Doug Raymond's schematic (version 3.3, page 2, available at https://www.mac-pac.org/), there are a couple of places where voltage gets in to the module (at least pins 2, 3, and 5), so maybe one (or more) of those has a higher resistance than it should. Note that the ignition switch, fuse #2, and their connections are also in these paths. It also looks like pins 1 and 28 need an excellent ground connection.

Alternatively, the drop in voltage when connected - assuming the GS911 is accurate - may indicate that the module is pulling more current than the circuit can support.

Hi, Paul,

Thanks for weighing in on this. I have Doug Raymond's schematics; my latest ones are dated 2/9/2013.

My stated 12.8 Volt measurement was from pin 1 to pin 3 right at the connector on the top of the ABS control unit. I pierce the wires with needle-like probes that are designed to do just that. Voltages on pins 2 and 5 are also approx. 12.8 Volts. Voltages do pull down a tad when the brakes are applied and the ABS unit loads the battery, of course.

Operating voltages appear to be there at the connector, all contacts are clean and shiny, and the connector has been off and on several times now so it's unlikely to be a poor contact as measured voltages are quite consistent.

The GS-911 indicated measurement must be some internal voltage but nowhere on the various forums have I found a statement of what it should be. I must assume that the 9.8 Volt GS-911 reading is correct... until someone with a 2004 RT and a GS-911 says otherwise.

I'm not registered on the GS-911 forums at this time.

In any case, regardless of whether the problem is internal low voltage or a failed (fragile) pressure sensor in the rear circuit, the unit gives all indication that it has failed... as they have a reputation to do.

179411 said:

Aaaand... no joy. Still getting '17433 Pressure in rear wheel circuit to (sic) low'. The module appears to be toast. Oddly, the GS-911 also reports module voltage as 9.8 Volts but measured right at the connector with DVM is approx. 12.8V. All other parameters in the green.

I'm considering my options.

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Possibly an issue with the rear brake master cylinder? I had to have on replaced under warranty on my 2004 bike when the bike would not pass a dealer bleed test. Just a thought...

Best,
DeVern

DeVern, I don't have an answer to that one. I believe that my '911 reported that the bleed test was satisfactory. Did the dealer use their GS-911 to find that fault?

179411 said:

DeVern, I don't have an answer to that one. I believe that my '911 reported that the bleed test was satisfactory. Did the dealer use their GS-911 to find that fault?

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Not GS911 but the BMW diagnostic computer. Bike had a faulty sensor in the rear reservoir so that was replaced and when the bike would not pass a bleed test on the BMW computer the master cylinder was replaced; bike subsequently passed the test.

I’m not sure I have a lot of faith in the GS911 bleed test. That same bike today will fail the test on my GS911, yet the brakes work excellently and when I’ve had the dealer do a flush they had no issues with the tests. YMMV, of course.

Best,
DeVern