DTC P1594: CHARGING SYSTEM VOLTAGE TOO HIGH
1. Turn ignition on with engine off. Using scan tool, actuate generator field driver. Using 12-volt test light, check for voltage at terminal No. 1 (Dark Green wire) on 2-wire connector at rear of generator. If test light blinks on and off, go to next step. If test light does not blink on and off, go to step 5 .
2. Start engine and allow engine to idle. Using scan tool, read target charging voltage. If target charging voltage is more than zero volts, go to next step. If target charging voltage is zero volts, go to step 4 .
3. With engine running, manually set engine speed to 1600 RPM. Using scan tool, read target charging voltage and battery voltage. Compare the 2 readings for 5 minutes. If difference between the 2 readings is more than one volt, replace PCM. Perform TEST VER-3A . PCM is located at passenger's side rear corner of engine compartment. If voltage difference is not more than one volt, allow engine to return to idle. Shut engine off. Turn ignition on with engine off. Using scan tool, check for DTCs. Record DTCs and FREEZE FRAME data, then clear DTCs. Perform TEST VER-3A .
4. Shut engine off. Using scan tool, read temperature of battery temperature sensor. Using thermometer, measure underhood temperature near battery tray. If underhood temperature is within 10 degrees of temperature of battery temperature sensor, replace PCM. Perform TEST VER-3A . PCM is located at passenger's side rear corner of engine compartment. If underhood temperature is not within 10 degrees of temperature of battery temperature sensor, replace battery temperature sensor. Perform TEST VER-3A .
5. Ensure ignition is off. Disconnect 2-wire connector at rear of generator. Disconnect round 2-wire connector at rear of the generator. Using ohmmeter, check resistance between ground and generator field driver terminal in the generator. This is the terminal on rear of generator that Dark Green wire in the round 2-wire connector fits on. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, short exists in the generator. Repair or replace generator as necessary. Perform TEST VER-3A .
6. Ensure ignition is off and 2-wire connector at rear of generator is still disconnected . Disconnect PCM connectors. PCM is located at passenger's side rear corner of engine compartment. Disconnect battery. Using ohmmeter, check resistance between ground and terminal No. 10 (Dark Green wire) on PCM connector C2. If resistance is 5 ohms or more, replace PCM. Perform TEST VER-3A . If resistance is less than 5 ohms, repair short to ground on Dark Green wire between generator and PCM. Perform TEST VER-3A .