1400 custom abs issue

[lucian]

2014 1400 custom  20,000 miles, first real problem encountered.  Abs light on steady and no speedometer, readout 0.  All other dash functions normal, also cruise control inoperable.  On occasion speedometer will resume working but will then stop again. This happened while on a road trip after going through some dirt construction sites and wet weather. I assumed probably a wheel speed sensor. When back home I checked the faults with Guzzzidiag and code po 502 was stored, rear wheel sensor, and safety code 6011 So I cleared the code and still had the problem intermittently.  I replaced the rear sensor and cleared the code again but to no avail, still no speedo or abs.
Have checked abs fuse and all related connectors and nothing obvious there. I checked abs power and ground continuity at abs connector, and continuity from abs connector to speed sensors , all good.
 Question,, are there other codes that can only be cleared by a dealer?   Do I need pads to perform abs diagnostics or are there other options?
 As I understand it there are logic errors that only dealers can access. I get that, but why they would make an abs system that  can take out your speedometer is beyond me. 

[Kiwi Dave]

The speedo will get its information from the same source(s) as the ABS.  I'm not sure whether it uses the front or rear sensor or both.  But this is an indication that all is not well with at least one of the sensors.

Perhaps your new sensor is faulty?  It would be unlikely (but not impossible) that both sensors failed simultaneously, but I'd recheck the rear one first.

[lucian]

Thank you Dave,  I have a ducati dealer nearby who thinks he can scan the abs off the two pin abs connector . I will pass along what he comes up with. I can live without abs , heck I can live without brakes, but with no speedo I'm doomed.

[beetle]

The ABS unit can lose its shit. I've seen it before. You need PADS to re-initialise it. That's worst case, however.

Have you tried recalibrating the TC? There may be some dependency.

[lucian]

Thanks Mark,  glad your on the mend!  I have had no luck with calibration as with no speedo I can't keep it at 18.75 mph in second gear in a straight line while rubbing my head and and whistling the Italian anthem.

[beetle]

I don't suppose you have an eeprom backup?

I fear you'll need to see someone with PADS.

[beetle]

I wonder if the old "disconnect the battery and leave the key on overnight" trick might work?

[Zoom Zoom]

I'm asking this as a question:

Are there not two wheel sensors because of the ABS? (One front and one rear?) Perhaps the wrong one was replaced???


John Henry

[lucian]

I wonder if the old "disconnect the battery and leave the key on overnight" trick might work?


This one got me thinking.

 If there are stored codes anywhere how to clear them without Pads? Any memory must be stored voltage of some sort, perhaps capacitor function. So I disconnected the battery and hooked up my voltmeter to the  battery  leads. Low and behold there was around 14 Mv hiding in there somewhere.  I connected the positive and negative  battery leads together and left them for half an hour. . The reading  dropped to 4Mv so I left it shorted for another half hour until it bottomed out at 1.5 Mv.
 
 The rest of the story,   just took it for a ride and as soon as I started rolling abs light went out and all functions are back to normal.
Summery , just clearing the PO205 rear sensor code with guzzi diag is not the only reset that needs to be performed to reset abs errors.
The rear wheel sensor was the culprit, but without this reset the abs would not reactivate even though the sensor had been replaced.
Thank you  all for the responses. It's nice to know how many MPH's over the limit I'm going again.
Big thank's to Beetle Aussies rule

[Chuck in Indiana]

Way to go, Lucian.. 

[beetle]

Fantastic! Good job!

[Ncdan]

You guys keep making all these discoveries and eventually we won't need the dealers PAD 45.00 diagnostic charge:)

[pat80flh]

In modern GM cars, removing the battery cables from the battery and holding/shorting  them together for 2 minutes is called a "global reset" . An engineer told me it discharges all capacitors. As the manufacturer continues to cheap out on built in scan tool functions, performing a global reset is becoming more common.

[Ncdan]

In my case with my TPS/demand sensor issue which the Po155 code identified the issue and a test with Guzzidag shows an issue with the sensor, woukd it be possible or logistical that this reset would or could fix the issue with my 2015 tourer throwing the code and going into limp mode. Lol, I'm grabbing at straws while waiting on the sensor that my buddy, Lucian has coming to me:)

[Zoom Zoom]

Why not Dan? You've got nothing to lose but time.

John Henry

[pat80flh]

  It certainly can't hurt anything. You may also try checking the connector at the  unitfor any backed out terminals, and find a comparable sized male terminal, see if the female terminals have proper drag.
    Most throttle by wire systems are made up of 2 pairs of sensors, I'll use a car as an example. The gas pedal(accelerator pedal position sensor) is made up of 2 tps's. One goes from 0-5volts, the other from 5-0 volts. This info is fed to the throttle worm gear motor. The throttle assembly also has 2 tps's. All 4 have to correspond, or for safety's sake the system is shut down(limp mode). I'd be looking closely at all wiring to both units, and if you have scan capabilities, see if you can can catch the offending parameter.   
   GM failures are almost always the throttle body, especially in cold wet weather. Not saying yours is, but the possibility exists.  But intermittent problems can very well be poor connections.

[Ncdan]

Thanks for the info and responses. I have a sensor come and in the meantime I may try that battery reset thing before I get to the remove the tank and install stage. At this point every points to the sensor itself. Lucian helped me run a diagnostic check through Guzzidag which indicated the TPS SENSOR was malfunctioning. Hopefully this thorn in the flesh will be fixed before I miss another scheduled ride:(