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	Fault Code 41 - Generator field not switching properly
	OBD1 DTC's for 1994-1997 Rams with Gas Engines
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Code 41 indicates a problem somewhere in the voltage regulator circuit in charging system.

1.    Verify that the battery is charged by using a digital volt meter to measure the terminal voltage. A fully charged battery will measure at least 12.6 V. If the battery is low, put it on a battery charger for at least four hours and check it again. If the battery is still low, replace it. A bad battery can set fault code 44.

2.   Turn the headlights on - the terminal voltage should not drop below 11.5 V. If it does, the battery should be taken to an auto parts store and put on a load tester. A bad cell will sometimes set code 44 and cause drivability problems.

3.    Start the engine - the meter should read 13.8 - 14.5 volts. If the voltage is below 13.8V, the battery is not charging. Measure the voltage at the back of the alternator output (the large wire terminal)

• if the voltage at the alternator terminal is more than 0.25 Volts higher than the battery voltage, the connection from the alternator to the battery is not good. The charge lead from from the alternator runs to the Power Distribution Center (PDC), through a 120 amp fuse link, then to the battery. A loose or corroded connection anywhere in this wiring will cause the battery to under charge.
• If the voltage at the back of the alternator is less than 13.8 volts, rev the engine and see if the voltage rises.
  • If the voltage does not rise, the field circuit must be checked - see below.
  • If it does, the alternator is weak, the belt is slipping, or the battery has a shorted cell.

4.    Turn the engine off, set the voltmeter to measure AC volts, and take a reading at the battery terminals. Now start the engine and measure the voltage at the alternator output - it should be almost identical to the voltage measured at the battery with the engine off. If the readings differ by more than 1 volt, there is a problem with the alternator diodes.

Alternator Field Circuit testing

Attach a frequency counter, tachometer, or dwell meter to the field control wire on the back of the alternator. This will be a dark green wire which goes to cavity 20 in the PCM.

• A frequency counter should detect pulses and display some frequency other than 0.
• A tachometer should indicated a speed other than zero.
• A dwell meter set to the 4 cylinder scale should read somewhere between 0° and 90°, but NOT 0° or 90°.

If the instrument of choice does not indicate that the circuit is pulsing, the dark green wire should be checked for continuity between the alternator and the PCM. If the wire is good, the PCM is faulty and must be replaced.

This page was edited on: May 3, 2004