volrem wrote:
Did I understand correctly that "PID that shows Generator/Alternator voltage set point (v) recorded 13.2" means requested voltage by control module?
Yes the PID shows Generator/Alternator voltage (v) as 13.2
Still confused. Does it mean measured voltage or requested voltage (command to alternator)?
Volrem in ids you have pids for the desired commanded voltage and the achieved voltages , its been a while since ive looked at one but the set point is always the higher of the two from initial start the other will then raise proportionaly within a calibrated time and if not reached will set a dtc .
Danny
Technician wrote:Can I ask you guys who test these alternator systems regular, can you vary the output from the alternator by somehow varying the command from the ECM?
Or is it just a case of running the engine at a fast idle and varying the loads by switching on more current demand from accessories?
Thanks
With Volvo this can be done easily using scan tool.
Unfortunately this is where volvo have the advantage , shared technologies across two brands but serial diagnostics very different. So unfortunately its loading circuits to get the ecm to increase the set point cmd .
I cant say I have ever needed to go any deeper.
Its either a charging fault so powers grounds battery etc , or an interuption or short on the linbus (good old shutter grille) im sure volrem will have seen plenty.
Danny
volrem wrote:
Did I understand correctly that "PID that shows Generator/Alternator voltage set point (v) recorded 13.2" means requested voltage by control module?
Yes the PID shows Generator/Alternator voltage (v) as 13.2
Still confused. Does it mean measured voltage or requested voltage (command to alternator)?
The short answer is I don't know TBH, however I can say that the voltage reading from the PID at 13.2 never changed during current loading or unloading, revving the engine up or allowing to return to idle, but live data on the digital voltmeter did adjust when loaded and unloaded, also with increased revs and return to idle.
I would take that pid as the set point for the alternator rather than the command , with you live data what was pcm supply voltage? Did this correspond to your 13.2v or did it read same as battery post?
Danny
Dcunning35 wrote:I would take that pid as the set point for the alternator rather than the command , with you live data what was pcm supply voltage? Did this correspond to your 13.2v or did it read same as battery post?
Danny
I was concerned about that when I refitted the alternator, however after cleaning all cable connections I managed to achieve 13.2 volts at the battery using a digital voltmeter, which varied with load applied, the PID data remained at 13.2V and did not change, the PCM battery supply remained at 12.3V and never changed.
Just like to edit to add;
Having searched the Pico library and found a known good LIN signal from the PCM, after comparing to the Fiesta LIN signal recorded, the two are identical and seems normal operation to me.