ABS Sensor test error 5

Hi, I have an intermittent error 5 showing on the ABS, It's a [-]96[/-] 2006 ST1300, So to establish the front and rear sensors are working can I ask if anyone could confirm this test should work.
If I start the bike on the main stand, select gear 1 and let the rear wheel spin the bike shows no error code, the ABS light stays constantly illuminated.
If I start the bike and spin the front wheel only, the ABS light stays constantly illuminated.
If I start the bike and select 1st gear and let the rear spin, then go to the front and spin that too, then the ABS light starts to flash.
Am I right in thinking both wheel sensors are working if it shows the error only when both wheels revolve?

Is there another way to test the sensors?

ta, in advance.

96 ST1300? Not trying to be smart, but is it a 96 ST1100 (which I might could be of help) or a 06 ST1300 (which I would be perfectly useless on)? IIRC, the ABS sensor codes are totally different between the two bikes.

Ah, sorry , yes its an 06 ST1300, sorry about the confusion.

(Fixed the year in the first post.)

Code 5 is a problem with the motor in the rear modulator, which means the ABS computer is either unable to sense that enough current is flowing through it or that it did and it can't detect the movement. There's a separate code (7) for a failure in the crank angle sensor, so that's probably not that.

Since you have to put up with the UK's patented British Road Crud, the first thing I'd do after checking the fuses is get a can of contact cleaner and clean all of the electrical contacts involved. There are two connectors on the modulator, a short sub-harness that connects to the main harness and one that connects the main harness to the brown socket on the ABS computer. If that doesn't help, there's a whole litany of diagnostics in the service manual that will narrow it down further.

One thing about the ABS computer that's different from the ECM: Once it logs a fault, it has to be cleared manually. You'll want to do that before each check to see if you've fixed it.

--Mark