2005 GEM E4, no 12 volt systems working but cart runs fine. 72 volt 10 amp fuse good. 1 amp 12 volt fuse good and have 72 volts to converter, have 12 volts on Pins 9 and 10 on voltage converter, but no 12 volts switched output from pins 7 and 8 on voltage converter. Replaced voltage converter with known good none from another cart, same conditions. I have no voltage on DC/DC enable on pin 3 of voltage converter when I turn key switch on, but LCD display does lite up. Should I have 12 volts on DC/DC enable when turn the key switch on ? if yes does this 12 volts get supplied back to the voltage converter through the PSDN ? Confused on 12 volt out, 12 volts switched on voltage converter. I can find no mention how the DC/DC enable works in the maintenance manual.
I have checked grounds both 12 volt and 72 volt and they all check out on the harness from the voltage converter to PSDM
If your car runs/drives, it means the DC Converter is making 12v unswitched/constant on pins 9 & 10. (ref 4, 5, & 6).
When KeyON, 12v feeds back to the converter from PSDM J4 PinD into the converter Pin3 and enables the Switched legs of the converter and feeds J4 pins A and B.
If you don’t have 12v on the enable wire at KeyON, then something may have upset your accessory timer (built into the PSDM). You could also try forcing the converter to kick on the switched 12v by jumping pins C and D.
(Note: the wire colors in the converter harness change through the years, but the pins/functions remain the same.)
OK, you have confirmed what I thought was going on. I guess I need to pull the PSDM and check on this timer, is this timer a replaceable item? Does it simply provide 12 volts to enable the switched 12 volt output when 12 volts is supplied to it? Manual says 30 second timer ?
Thanks for the great feedback !!
Jim
Did you confirm you do not have anything coming out on the J4 Pin D wire?
What happens when you jump the two?
I suppose it could also be a cold solder/bad contact on the Key Relay, or the pin on the circuit board itself.
Timer is just a guess. I doubt it was designed to be serviceable. Not much is known about the inner workings of the PSDM. Here is a peek if you feel really ambitious and think you can track it down.
If you get lucky, you might find a cratered diode or resistor related to your circuit.
Note the chips have had their numbers wiped before the coating was applied. Somebody was rather proud and protective of their work.
Perhaps something can be gleaned from the events that put you in this state of dysfunction?
Yes confirmed nothing coming out of J4 Pin D wire, have not yet jumped C & D on J4 as it is raining here now. I am trying to understand the logic on why we need to delay switched 12 volt power when we turn the key switch on?
No events to relate to this loss of switched 12 volt power. This happened a while back and before I could get into it all was working again. I have reseated all the connectors on the PSDM, all contacts look good no corrosion. So maybe a cold solder joint or bad relay on the circuit board.
Jim
It’s not delay ON, It’s delay OFF after KeyOff.
Don’t ask me why. Nobody has ever explained why it is there. One guess was that it had something to do with properly shutting down the controller and let it drain the caps so it doesn’t back feed into other systems, but it could be that someone high up the chain thought it was a cool feature to leave lights on and go up to a dark front door at night.
OK that makes sense. I will remove the PDSM and see what I can find. Thanks for the help.
Jim
