Talyn
NAXJA Forum User
- Location
- Radford, Communistwealth of Virginia
I'm working on a 93 XJ 4.0L. Not mine though. Its have an overcharging issue. Battery is good. I had cleaned the grounds and it seemed like it was fixed. However, today I was charging the AC system and it started doing it again. It is throwing codes 41 and 46. 41 is for alternator field issue, and 46 is for overcharging. It was charging around 16 volts. I know the PCM controls the charging, and does so by PWM on one the negative side of teh connection on the alternator. The other is for a positive from the ASD relay. The third connection is of course for the positive charge side.
I have performed the following diagnostics:
a)With the plug disconnected the alternator does not charge, as expected.
b)With only the + side of the field energize (ASD relay) connected it is charging 16+
c)With both connected it behaves the same way as in b.
From the way I understand the system is that both of the field wires need to be connected in order for it to charge, not just the positive side from the ASD.
I'm thinking the alternator is bad but I would like other opinions.
Also, anyone know how to test the PCM side? A simple voltage test isn't good enough as it pulses the - side. I can measure Hertz, but I have no data on what it should be when it telling the alternator to put out more, or less. Any numbers on that?
-Chris
I have performed the following diagnostics:
a)With the plug disconnected the alternator does not charge, as expected.
b)With only the + side of the field energize (ASD relay) connected it is charging 16+
c)With both connected it behaves the same way as in b.
From the way I understand the system is that both of the field wires need to be connected in order for it to charge, not just the positive side from the ASD.
I'm thinking the alternator is bad but I would like other opinions.
Also, anyone know how to test the PCM side? A simple voltage test isn't good enough as it pulses the - side. I can measure Hertz, but I have no data on what it should be when it telling the alternator to put out more, or less. Any numbers on that?
-Chris