servo brake failure abroad -plea for help

[DaveH]

Arrived South of France yesterday. Everything fine. Went to start GS this morning - no brake servo. Brake failure lights showing code 1 - residual braking only. Engine runs ok. Have tried connecting GS911 but am getting `no response from controller` message for both engine and abs ecu. ?? Checked wiring,battery voltage, brake light bulb,brake microswithches. Am limited to data access on mobile so any help greatly appreciated. email [email protected]. Bike is 2003 twin spark with servo abs. Thanks guys..

 

[Steptoe]

. Have tried connecting GS911 but am getting `no response from controller` message for both engine and abs ecu. ?? ..

Are you using the latest GS911 firmware ? The old one had this "reading" problem.

 

[DaveH]

firmware

pretty sure its up to date - am running the latest beta software release updated via the unit. have only got access to internet via windows mobile so dont know if I can download\transfer a newer version anyway. Been for a run on the bike. residual braking not as bad as the horror stories Ive read, no brake light is the biggest problem.

 

[DaveH]

ABS circuit board ??

Decided to spend the rest of the holiday with the residual brakes. Not at all bad once you get used to 'em.
Got home last night - hooking the GS911 up in the workshop gives 'k line stuck low message.'
After a bit of head scratching, have removed the plug from the ABS unit and tried diagnostics again.
This time it will read the engine ECU so I guess the circuit board in the servo unit is farked.
Anyone else had any experience of this before I perform a servoectomy ??

 

[ahutcheon]

K-line is the ECU diagnostics serial line. Most of my experience was in transporting K-line higher level diagnostic protocols over CAN bus, so I'm not great on the electrical details. I'm pretty sure it's a variable speed serial protocol - think ruggedised RS232 - where the diagnostic box can initiate a conversation with the ECU at very low baud rate (reduces polling overhead in the ECU) then switch to a higher rate for the conversation.

Details don't matter, sounds like you've got a short or other fault pulling the K-line to earth in the ABS unit (I assume the K-line on an 1150GS is common to multiple ECUs at the diagnostic connector, and that unplugging the ABS is removing the fault so it's not in the loom).

Short answer: I'd be pretty suspicious of the ABS ECU, since it's stopped doing the brakes and lost diagnostics. Funny fault if the two have a common cause - I'd have expected the K-line to be a UART on the microcontroller and an external driver for the 12v signal level.

 

[DaveH]

I'd have expected the K-line to be a UART on the microcontroller and an external driver for the 12v signal level.

Yes - just what I was thinking

Seriously - thanks for the reply - I reckon the ABS CPU is toast and it lloks like the servo unit will have to be consigned to the bin.

Dave H

 

[ahutcheon]

Yes - just what I was thinking

Seriously - thanks for the reply - I reckon the ABS CPU is toast and it lloks like the servo unit will have to be consigned to the bin.

Dave H

Apologies for the jargon, don't really have a good english translation...

I'm kinda waiting for my servo ABS to die, so keen to find out what goes wrong. Kinda wish I had a circuit diagram and dead ones to pay with, but I know just enough to be dangerous (not good with brakes) and I'm in NZ these days.