Voltage issue when starting...
#1
Voltage issue when starting...
So recently my truck (1994 12v with 125k on it) has been having this weird voltage problem when starting cold. The alternator will take like 10 seconds to kick in when it first starts and when it is on it will go from like 14.5v to around 12.5v.... it like flickers the lights from the fluctuating voltage. But after its warmed up it's fine and doesnt do it again.... not sure if I should replace the alternator or if it's some voltage regulator. It might be the factory alternator so I'm not sure....
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nothingbutdarts (10-23-2018)
#3
Registered User
gorms is right.
From my AlldataDIY/FSM info:
OPERATION
When energized, the air heater will warm incoming air as it enters the intake manifold. The air heater is energized by the Powertrain Control Module (PCM) through the air heater relays. Two heavy duty cables connect the two air heater elements to the two air heater relays. Each of these cables will supply approximately 95 amps at 12 volts to an individual heating element within the heater block assembly. Intake manifold air temperature determines when the heater is energized. They may be energized before cranking and after cranking, or both. The heater is not energized during cranking.
Pre-Heat Cycle
The PCM powers up when the ignition key is turned to the ON position. If intake manifold air temperature is 15°C (59°F) or below, the air heater is energized and the wait-to-start warning lamp is illuminated. The heater is energized for a specific amount of time. Refer to the Air Heater Cycle Chart.
Once the heater has cycled, the wait-to-start warning lamp goes out. While the engine is cranked, the heater is not energized.
Post-Heat Cycle
After engine has been started, the post-heat cycle will begin if intake manifold air temperature was 15°C (59°F) or below when ignition switch was turned ON. Depending upon intake manifold temperature, either: the heater is energized, or they are cycled on and off (when one is energized, the other is not). The time the heater is energized depends upon intake manifold air temperature. Refer to the Air Heater Cycle Chart
The description mentions intake air temp of 59 degrees - I find mine seems to trigger around 50 degrees.
From my AlldataDIY/FSM info:
OPERATION
When energized, the air heater will warm incoming air as it enters the intake manifold. The air heater is energized by the Powertrain Control Module (PCM) through the air heater relays. Two heavy duty cables connect the two air heater elements to the two air heater relays. Each of these cables will supply approximately 95 amps at 12 volts to an individual heating element within the heater block assembly. Intake manifold air temperature determines when the heater is energized. They may be energized before cranking and after cranking, or both. The heater is not energized during cranking.
Pre-Heat Cycle
The PCM powers up when the ignition key is turned to the ON position. If intake manifold air temperature is 15°C (59°F) or below, the air heater is energized and the wait-to-start warning lamp is illuminated. The heater is energized for a specific amount of time. Refer to the Air Heater Cycle Chart.
Once the heater has cycled, the wait-to-start warning lamp goes out. While the engine is cranked, the heater is not energized.
Post-Heat Cycle
After engine has been started, the post-heat cycle will begin if intake manifold air temperature was 15°C (59°F) or below when ignition switch was turned ON. Depending upon intake manifold temperature, either: the heater is energized, or they are cycled on and off (when one is energized, the other is not). The time the heater is energized depends upon intake manifold air temperature. Refer to the Air Heater Cycle Chart
The description mentions intake air temp of 59 degrees - I find mine seems to trigger around 50 degrees.
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nothingbutdarts (10-23-2018)
#4
Registered User
Ever Fall I read several threads on DTR about electrical "issues" that just end up being the grid heaters just doing their job.
Nothing to worry about.
Nothing to worry about.
#5
Registered User
#6
Registered User
Yep, its a regular - on other Dodge Cummins forums, too... I think it's even mentioned in the owners' manual - I seem to remember seeing it in my owner's manual when I bought the truck used
#7
Registered User
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