Battery light on

[Otterboy]

Battery light in the odometer panel came on after replacing the old alternator with a new DC Power 270 amp alternator. 2009 e350 smb with 6.0 diesel with 2 engine batteries and 2 house batteries. No error codes and the new alternator seems to be charging well with 14.2 to 14.5 volts after idling for a minute which is much better than the old alternator. So what could be causing the light?

[kbeefy]

Battery light is usually a low charge, but it sounds like yours is OK. Can you check the voltage at the OBDII port?

[Otterboy]

That’s where I got my voltage numbers. I have an SCT tuner plugged in to that port and configured to show voltage and other things while running. This light never came on before the new alternator even though sometimes the voltage looked dangerously low. But the new alternator seems to be charging just fine including better charging of the house batteries as well. Can it mean that whatever mechanism triggers the battery light does not like the voltages I am seeing now?

[REF]

Did you replace the cables too? Could be a ground issue, check that all your connections are secure.

[kbeefy]

Have you contacted DC power about it?

[kbeefy]

PINPOINT TEST J: THE CHARGING SYSTEM WARNING INDICATOR IS ON WITH THE ENGINE RUNNING AND THE BATTERY INCREASES VOLTAGE

1. J1 CHECK I CIRCUIT 904 (LG/RD) FOR A SHORT TO GROUND
   • Ignition OFF.
   • Disconnect: Generator C1104A.
   • Ignition ON.
   • With the key in the ON position, check the charging system warning indicator.
   • Is the charging system warning indicator illuminated?
   • Yes: REPAIR the I circuit 904 (LG/RD). TEST the system for normal operation.
   • No: INSTALL a new generator. REFER to GENERATOR - DIESEL ENGINES, SINGLE GENERATOR.

[kbeefy]

Also of note:


Normal Operation

With the engine running, the charging system warning indicator is off. The sense A circuit 35 (OG/LB) to the generator field coil is 13- 15 volts. The S (stator) circuit (internal to the generator) is used to feed back a voltage signal from the generator to the voltage regulator. This voltage is used by the PCM to turn off the charging system warning indicator. The positive battery output (B+) circuit 1119 (RD) is the generator output supplied to the battery and the electrical system.





The alternator could have an internal fault and isn't sending the stator voltage to the PCM.

[Otterboy]

Thanks all for tips. I will return to the shop that put in the alternator tomorrow and will conference call with DC Power. The shop is telling me the alternator is overcharging but I have not seen any reading over the alternator spec of 14.8 volts and I do not trust that diagnosis. The light always is off on initial key on and initial startup. It comes on a minute + after the glow plugs appear to shut down and voltage rises to the 14+ range. Perhaps this is an internal voltage regulator issue?

[Scalf77]

Short answer is yes. It would be the primary source of the indicator coming on. Your indicator circuit is simple, no PCM involved on single gen solution. The positive side is tied to ignition circuit, the ground side is tied to the voltage regulator. The line is grounded when the alternator is not running. When the regulator/alternator becomes operational it releases the ground connection and the light goes off.

[Otterboy]

I hate that this friggin forum logs you out before your reply is complete and forces you to login again and start over. Anyway after conversation between DC Power and the shop and various remedies were tried they supplied a new alternator but after installation the problem persisted. Battery light comes on a minute or so after startup. Excess voltage error code with all voltage levels seemingly within spec (14.5 volts or less). Is there something DC Power and the shop are missing?