DTC P1682: CHARGING SYSTEM VOLTAGE TOO LOW Dodge Ram Wagon B1500

Note. For connector terminal identification, see CONNECTOR IDENTIFICATION . For circuit identification and wiring diagram, see RAM VAN & RAM WAGON wiring diagram in WIRING DIAGRAMS article.

Note. DTC P1682: CHARGING SYSTEM VOLTAGE TOO LOW is monitored with engine running at more than 1500 RPM for more than 25 seconds. DTC may be stored in Powertrain Control Module (PCM) when PCM senses attempts to regulate generator field indicate no field problems but voltage output does not increase. Possible causes are: defective Battery Temperature Sensor (BTS), defective generator, defective PCM, defective connector or defective wiring.

1. Turn ignition off. Ensure battery is fully charged and generator belt and tension are okay. Start engine and allow it to idle. Using scan tool, read TARGET CHARGING voltage. If voltage is more than 15.1 volts, go to next step. If voltage is 15.1 volts or less, go to step 5).
2. Turn ignition on, with engine off. Start engine and allow it to idle. Using scan tool, read BTS temperature. Using a thermometer, measure underhood temperature near battery tray. If BTS temperature is not within 10 degrees of underhood temperature, go to next step. If BTS temperature is within 10 degrees of underhood temperature, go to step 5).
3. Turn ignition off. Disconnect BTS connector. BTS is located under battery. Clean and/or repair connector as necessary. Connect jumper wire across BTS terminals. Turn ignition on, with engine off. Using scan tool, read BTS voltage. If voltage is zero, replace BTS. Perform TEST VER-3A. If voltage is not zero, go to next step.
4. At this time, PCM is assumed to be defective. Replace PCM. Perform TEST VER-3A.
5. Ensure engine is still idling Turn all accessories off. Manually set engine speed to 1600 RPM. Using scan tool, read TARGET CHARGING voltage and CHARGING voltage. Compare readings and monitor voltage. If voltage difference is more than one volt, go to next step. If voltage difference is not more than one volt, go to step 13).
6. Ensure engine is still idling Using a voltmeter, check voltage between positive battery terminal on generator and positive battery post. If voltage is more than .4 volt, repair power circuit between generator and battery for high resistance. Perform TEST VER-3A. If voltage is .4 volt or less, go to next step.
7. Turn engine off. Turn ignition on, with engine off. Using scan tool, actuate Generator (GEN) field driver circuit. Using a voltmeter, check voltage on both generator field terminals. If voltage is less than 3 volts at either terminal, go to next step. If voltage is 3 volts or more at both terminals, charging system is okay at this time. Perform TEST VER-3A.
8. Turn ignition off. Using a voltmeter, check voltage between generator case and negative battery post. Start engine and run to normal operating temperature. If voltage is .1 volt or less, go to next step. If voltage is more than .1 volt, repair generator ground circuit for high resistance. Perform TEST VER-3A.
9. Turn ignition off. Disconnect battery cables and PCM connectors. PCM is located in engine compartment. See PCM LOCATION table under SYSTEM DIAGNOSTICS. Using an ohmmeter, check resistance between ground and PCM connector, GEN field driver circuit (Dark Green/White wire). If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair GEN field driver circuit for short to ground and replace PCM. Perform TEST VER-3A.
10. Turn ignition off. Ensure battery cables and PCM connectors are still disconnected. Using ohmmeter, check resistance of GEN field driver circuit between PCM and generator. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open GEN field driver circuit. Perform TEST VER-3A.
11. Turn ignition off. Ensure battery cables and PCM connectors are still disconnected. Using ohmmeter, check resistance of GEN field source circuit (White/Dark Blue wire) between PCM and generator. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open GEN field source circuit. Perform TEST VER-3A.
12. Turn ignition off. Ensure battery cables and PCM connectors are still disconnected. Using ohmmeter, check resistance between ground and PCM connector, GEN field source circuit (White/Dark Blue wire). If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair GEN field source circuit for short to ground and replace PCM. Perform TEST VER-3A.
13. At this time, PCM is assumed to be defective. Replace PCM. Perform TEST VER-3A.
14. Start engine and allow it to idle. Using a voltmeter, check voltage between positive battery terminal on generator and positive battery post. If voltage is more than .4 volt, repair power circuit between generator and battery for high resistance. Perform TEST VER-3A. If voltage is .4 volt or less, go to next step.
15. Turn ignition off. Using a voltmeter, check voltage between generator case and negative battery post. Start engine and run to normal operating temperature. If voltage is .1 volt or less, test is complete. If voltage is more than .1 volt, repair generator ground circuit for high resistance. Perform TEST VER-3A.