General Category > ABS related issues

F650 CS 2 - spark 2005 : 1508: Rear sensor fault, signal implausible.

(1/4) > >>

stardust_59:
Hi everyone,
perhaps you can enlighten me on ABS fault 1508 which seems to be a sensor fault or signal path fault to the ABS. 

Description:

On a 2005 F650 CS 2 spark the ABS light came on.

The first fault showed 12772: Rear sensor fault, resistive.

After removing the rear ABS sensor from the axle housing at the excenter it showed iron dust and what seemed brake dust.
The rear axle housing and eccentric were cleaned with isopropyl alcohol and compressed air.

Another sensor was installed.
After installing the replacement sensor

1508: Rear sensor fault, signal implausible.
was shown.

The sensor was checked before installation and showed 3.1 kOhm resistance.
The original sensor , thought to be defective also showed 3 kOhm resistance.

The position of the eccentric axle housing was left unchanged.

Observation:

After installing the replacement sensor, the bike was driven for a couple of meters.
The ABS light turned on again.
When applying the rear brake - the ABS would 'fall through'.
That is - first pressure builds up on the brake pedal and is then released.
The effect is the same as when bleeding the ABS - which was done a few days before.
It seems that the ABS valve opened for some odd reason.

Wheel bearings are ok - there is no play at the rear hollow axle.
No rough running or grinding noises that would indicate defective bearings.

Logs:


#2018-01-01 19:33:59
#GS-911 Android V1.2
#F650CS 2 spark
Controller name: BMS-C2
Part: 07689873
HW Version: A
Diag Idx: 5
Manufacturing Date: 2005-03-08
Program release: 180E
Date release:: 180EE606
Manufacturer:: Hella KG
=========================

#2018-01-03 21:13:31
#GS-911 Android V1.2
#F650CS 2 spark
Controller name: ABS-N
Part: 07661881
HW Version: 17
Coding Idx: 0
Diag Idx: 11
Manufacturing Date: 2004-03-31
Software version: 17
Manufacturer: Nippon
==========================

#2018-01-03 21:13:36
#GS-911 Android V1.2
#F650CS 2 spark
1508: Rear sensor fault, signal implausible.

Question:

Does anyone have a reference resistance for the ABS sensors ?
If the copper is intact there should be a well defined resistance for said coil which allows to check if the sensor is intact or defective.

After having read about the effects of metal dust on magnetic ABS sensors , observed on R1200 GS and similar models - cleaning of the axle bearing area was the first thing to be done.
Did not help though...

Does anyone have an idea what else might have to be taken into consideration for diagnosing the root cause of E 1508 ?

Thanks & regards
Jan

WayneC:
The wheel sensors are Bosch DF11 active components not passive so they are not a component you take resistance measurements from, the measurements are meaningless. There is a thread on the forum which shows how to work with DF11 sensors using low cost DSO on an R1200, it is worth reading

The "implausible signal" error code indicates there is likely a wiring fault back to the dash, was the replacement sensor fitted a new sensor ?

stardust_59:
WayneC,
thanks for the hint on the sensor type and DSO check. Good point.

I do have a signal generator and some HP digital and analog Osci available, if necessary.
Will look into that.

Dash - good point.
The owner fitted LED instead of incandescent bulbs assuming that 'it doesn't matter'.
I wasn't too sure about 'doesn't matter'...

Replacement sensor is a used one from a well known seller (BMW Salvage , motorcycle breaker).
Seller claims that it was of an operational vehicle.

My taking of the 'signal implausible' error was that the BMS and the ABS may have differing signal input.
As the rear sensor also provides the dash or BMS with rear wheel roation signal - I was a bit puzzled about where to go next..

Time to fire up the lab...



I'll report back with whatever may be relevant.

Jan

WayneC:
I should have said ABS not Dash, on an ABS machine the rear wheel sensor goes to the ABS then the signal is extended to the Dash & back to BMS

You dont need a signal generator, all you need to do is spin the wheel and you should see around 1v on a multi meter set to AC range

The CRO can be hooked up to the sensor lead to display the pulses, having a 100 ohm resistor in series in the lead and the CRO across the resistor would be the best but search for the thread I referred to, the owner learned to use a DSO and prove a sensor all the the space of 24 hours

stardust_59:
WayneC, thanks again for clarifying.

signal path:

rear wheel ==> ABS ==> Dash ==> BMS

Quite a few fault points in there.

Ok - I'll check the sensors first.
Next - all connections from ABS to Dash to BMS.
The ABS connector being to most interesting , I guess.
We'll see.
I have a nice todo list now.

Any keywords to find the thread with the DF11 measurements ?
I'm out of luck finding it.
But I guess doing the AC voltage measurement will be good enough for a start.

Jan

Navigation

[0] Message Index

[#] Next page