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2013 Nissan juke 1.6 l. Alternator is not charging battery even though the alternator has tested good. Initially after reinstallation of alternator, charging voltage was present but erratic. Three-wire harness (ECU, dash light, full-time 12 volt) only 12 volts presents has been confirmed or tested. First test drive no issues noticed with charging voltage, other than fluctuating between 14.0 - 13.3volts. During the drive to return vehicle to customer, it went from battery to charging voltage over and over again. I made one curious observation, when gas pedal was pressed charging voltage disappeared only to reappear when coasting with no gas pedal. I would appreciate any advice or help thank you.
Can the alternator keep up if you turn on all the loads?
From identifix:
Tests/Procedures:
1. Check scan data for alternator percentage duty while monitoring the charging voltage. If the alternator is 0% duty, the alternator should charge normally. A 37.5% duty charges about 12.6-12.8 volts. A 15% duty will result in battery voltage around 12.1 volts.
2. If the alternator duty is at 0% and the alternator is not charging, verify the other alternator voltages before condemning the alternator. If the charging voltage is lower, but there is an alternator percentage duty, the ECM is likely commanding the alternator to turn off. If there is light electrical load on the electrical system, the ECM can turn off the alternator. The ECM can also turn off or reduce the alternator load on the engine under hard acceleration for increased power so the system may be working normally.
Tech Tips:
The Intelligent Power Distribution Module (IPDM) can control the charging voltage by duty cycling to ground the Beige wire. With 0% duty (no ground) on the Beige wire, the alternator should charge normally. The alternator sends out approximately 6.0-6.5 volts on the Beige wire and the IPDM can duty cycle that wire to ground (0-6 volt square wave) to lower the charging voltage. Lowering charging output of the alternator can reduce load on the engine. The Engine Control Module (ECM) receives inputs such as the battery current sensor and engine load from the Mass Air Flow (MAF) sensor, etc. and the ECM communicates on Controller Area Network (CAN) to the IPDM to have the IPDM duty cycle the control wire (Beige wire) to ground to reduce alternator load as necessary.
