Medium and Heavy Trucks
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Hi my name is***** with me while I pull up some info on your code.
543 — PCM/IDM DTC 543 is set by the • DTC 543 can be set If IDM power is low, DTCCommunications Fault PCM when the PCM is not when the CAN 2 lines 543 can be set.communicating with the between the PCM andIDM. IDM are shorted toground, VREF, battery orthe current is open.• When DTC 543 is activethe amber ENGINEindicator is illuminated
Check the fuses and relays for the IDM as well as for problems in the wiring harness/connectors.
Check in the Battery box for an ECM/IDM inline fuse and inspect the wiring as well. Let me know
Since it now wont work on the other bus I would be concerned about a short in the wiring damaging the IDMs.
Thanks for the info. Monitor the voltage to the IDM and check the charging system as well. Make sure you have no voltage spikes or issues. Let me know
Thanks for the update. The other IDM failed with just the key switch on or after trying to crank the engine over? I ask because I am concerned with a short. if not in the wiring harness or bad main ground, you could have a shorting alternator, shorting starter, ignition switch, possible internal battery issue. The battery can be tested with a digital tester for internal issues, the starter and alternator can be bench tested. The wiring harness and be inspected and continuity checked with an OHM meter including grounds.
Its possible the other IDM failed at that time but Id be leary on trying another one if there is a short or backfeed frying the IDMs in the circuit somewhere.