Charging System - Generators & Regulators Jeep Grand Cherokee WJ

IDENTIFICATION

GENERATOR APPLICATION

DESCRIPTION

Charging system consists of a Powertrain Control Module (PCM), generator, Malfunction Indicator Light (MIL) and battery. Generator consists of a rotor, stator, rectifiers, front and rear covers and drive pulley. Generator is serviced as a complete unit only. Voltage regulation is controlled by the PCM. Electronic Voltage Regulator (EVR) is not a separate component, but a circuit located within the PCM. If EVR circuit is defective, PCM must be replaced.

OPERATION

The amount of amperage produced by the generator is controlled by Electronic Voltage Regulator (EVR) circuitry within the Powertrain Control Module (PCM). EVR circuity is connected in series with the generator field driver terminal and ground. A Battery Temperature Sensor (BTS), located in battery tray, is used to sense battery temperature. Sensed battery temperature and data from monitored line voltage is used by PCM to adjust battery charging rate. This is accomplished by cycling the ground path to control the strength of generator rotor magnetic field. PCM then compensates and regulates generator amperage output accordingly.

The PCM monitors critical input to control fuel injection, ignition, emission and other engine management functions. The PCM is also programmed to monitor charging system related circuits

1. Battery feed to PCM.
2. Generator field control.
3. Battery charging voltage (high and low).

If a problem is sensed in a monitored circuit, a Diagnostic Trouble Code (DTC) will be stored in PCM memory and Malfunction Indicator Light (MIL) will illuminate, provided specific criteria have been met. DTCs can be read using MIL, Chrysler's Diagnostic Readout Box (DRBIII(R)), or a generic scan tool.

Note. DTC is erased from memory if failure does not reoccur after 40 engine starts.

Certain DTCs cause MIL to illuminate and PCM to enter limp-in mode. In limp-in mode, PCM attempts to compensate for particular component failure by substituting information from other sources. This allows vehicle operation until proper repairs are made.

BELT TENSION

BELT ADJUSTMENT

TROUBLE SHOOTING

Note. For additional trouble shooting, see TROUBLE SHOOTING article in GENERAL INFORMATION.

INITIAL CHECKS

Before proceeding with charging system diagnosis, ensure following conditions are met

1. Battery is fully charged and in good condition.
2. Battery cables are in good condition with connections clean and secure.
3. Generator belt is in good condition and properly tightened. See «BELT ADJUSTMENT»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators) table under ADJUSTMENTS.
4. Generator and PCM wiring harness connections are clean and tight.
5. Engine ground strap is in place.

UNSTEADY OR LOW CHARGING

Check for loose generator belt, charging resistance too high, loose generator ground wire, corroded battery terminals or faulty generator. See BELT ADJUSTMENT table under ADJUSTMENTS.

OVERCHARGING

Check for grounded generator field wiring or faulty generator. See WIRING DIAGRAMS .

NOISY GENERATOR

Check for worn or frayed drive belt, loose generator mounting, or faulty generator. See TORQUE SPECIFICATIONS for generator mounting bolt tension.

ON-VEHICLE TESTING

VOLTAGE DROP TEST

Note. Voltage drop test determines amount of resistance in circuits between generator and battery.

1. Ensure battery is in good condition and is fully charged. Clean battery terminals (if necessary). Using a voltmeter, connect positive lead to generator B+ terminal stud (not the nut). Connect voltmeter negative lead to positive battery post. Connect tachometer to engine. Fully engage parking brake, and place gear selector in Neutral position. Start engine and run for 2 minutes to allow for warm-up.
2. Turn A/C system on, A/C-heater blower motor to high speed and headlights on high beam. Increase engine speed to 2400 RPM. Voltmeter reading should not be more than 0.6 volt.
3. If voltage drop is more than 0.6 volt, inspect, clean and tighten all connections between generator B+ terminal and positive battery post. Voltage drop test may be performed at each connection to locate connection with excessive resistance. If resistance tests are satisfactory, reduce engine speed, turn off all electrical loads and ignition switch.
4. Using a voltmeter, connect positive lead to generator ground terminal stud (not the nut). Connect voltmeter negative lead to negative battery post. Connect tachometer to engine. Fully engage parking brake, and place gear selector in Neutral position. Start engine and run for 2 minutes to allow for warm-up.
5. Turn A/C system on, A/C-heater blower motor to high speed and headlights on high beam. Increase engine speed to 2400 RPM. Voltmeter reading should not be more than 0.3 volt.
6. If voltage drop is more than 0.3 volt, inspect, clean and tighten all connections between generator ground terminal and negative battery post. Voltage drop test may be performed at each connection to locate connection with excessive resistance. If resistance tests are satisfactory, reduce engine speed and turn off all electrical loads and ignition switch.

CURRENT OUTPUT TEST

Perform VOLTAGE DROP TEST before continuing with this test. Perform test soon after starting engine, as charging amperage will drop quickly. A volt/amp tester equipped with both a battery load control (carbon pile rheostat) and an inductive type pick-up clamp is required to perform this test. Follow tester manufacturer's instructions to perform current output test.

OUTPUT VOLTAGE TEST

1. Before performing this test, ensure battery is fully charged. Connect voltmeter leads across battery terminals. Record voltage with ignition switch and all electrical loads off. Fully engage parking brake, and place gear selector in Park position.
2. Start engine and operate at normal operating temperature. Record voltage with engine speed at 1500 RPM and no electrical loads. Voltage should not be more than voltage recorded in step 1 by more than 2.5 volts. If voltage is as specified, go to next step. If voltage is not as specified, check charging system. For Diagnostic Trouble Codes (DTC), see «SELF-DIAGNOSTIC SYSTEM»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__self-diagnostic-system) .
3. Record voltage with engine speed at 2000 RPM, blower motor on high and headlights on high beam. Voltage should be 0.5 volt or more than voltage reading previously recorded in step 1 . If voltage is less than 0.5 volt or more than voltage reading previously recorded in step 1 , check charging system. See «SELF-DIAGNOSTIC SYSTEM»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__self-diagnostic-system) . If voltage tests are as specified, reduce engine speed, and turn off blower motor, headlights and ignition switch.

BATTERY TEMPERATURE SENSOR (BTS)

Connect scan tool. Turn ignition on. Using scan tool, select SENSORS. Read and record ambient battery temperature. Using a temperature probe, read and record the air temperature near the BTS, located on bottom of battery tray. If readings vary by more than 10°F, replace BTS. If readings vary by 10°F or less, check wiring, terminals and connectors. Repair as necessary. Start engine. Check BTS output while wiggling wiring. If temperature changes, repair wiring as necessary. If no problems are found, test is complete.

SELF-DIAGNOSTIC SYSTEM

Note. Tests are written for use with Chrysler's Diagnostic Readout Box (DRBIII(R)). A generic scan tool may not be able to perform all necessary test functions.

If a problem is sensed in a monitored circuit, a Diagnostic Trouble Code (DTC) will be stored in PCM and MIL will come on, provided specific criteria are met. PCM will then enter limp-in mode, substituting information from other sources to compensate for component failure. Vehicle is operational in limp-in mode, but driveability may not be optimal.

A specific DTC results from a particular system failure. DTC only indicates problem circuit. It does not identify specific component failure in the circuit.

If problem is repaired or ceases to exist, PCM automatically clears DTC after 40 ignition on-off cycles. DTCs can also be cleared using scan tool. See CLEARING DIAGNOSTIC TROUBLE CODES .

SERVICE PRECAUTIONS

Before proceeding with diagnosis, observe following precautions

1. Ensure battery is fully charged.
2. Probe PCM connector from pin side. DO NOT backprobe PCM connector or probe wires through insulation.
3. DO NOT cause short circuits when performing electrical tests. This will set additional DTCs, making diagnosis of original problem more difficult.
4. DO NOT use a test light in place of a voltmeter.
5. Always begin repair with lowest DTC number (MIL) or first DTC displayed (scan tool).
6. Always perform appropriate verification (VER) test after repairs are made.
7. Always disconnect scan tool after use.
8. Always disconnect scan tool before charging battery.

Note. PCM cannot diagnose every charging system problem. If fault still exists after performing self-diagnostic procedures, proceed to ON-VEHICLE TESTING .

RETRIEVING DIAGNOSTIC TROUBLE CODES

1. Attempt to start engine. If necessary, crank engine for up to 10 seconds. Read and record Diagnostic Trouble Codes (DTC). If scan tool screen is blank or displays NO RESPONSE, go to «SCAN TOOL PROBLEMS & ERROR MESSAGES»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators) .
2. If DTCs are displayed, see «DIAGNOSTIC TROUBLE CODE IDENTIFICATION»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators) table. Only DTCs relating to charging system are listed. For all other DTCs, see appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE. If no DTCs are displayed, go to «CHARGING SYSTEM NO CODE TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__charging-system-no-code-test) under SYSTEM TESTS.

DIAGNOSTIC TROUBLE CODE IDENTIFICATION

CLEARING DIAGNOSTIC TROUBLE CODES

PCM automatically clears DTCs from PCM memory after 40 ignition on-off cycles. DTCs can also be cleared using scan tool by following scan tool manufacturer's instructions.

Blank Message Screen

Check for loose cable connections or bad cable. If cable connections and cable are okay, check voltage at DLC terminal No. 16 (Tan/Black wire on Cherokee, Pink/Red wire on Grand Cherokee and Pink/White wire on Wrangler). Voltage should be at least 11 volts. If voltage is not as specified, check wiring circuit and necessary fuses. See WIRING DIAGRAMS .

DTC P0622: GENERATOR FIELD NOT SWITCHING PROPERLY

Note. To identify field terminals, measure voltage between ground and each field terminal with engine running. Positive field terminal voltage should be 12.5-14.5 volts. Negative field terminal voltage should be 3-8 volts less than battery voltage.

Note. Diagnostic Trouble Code (DTC) is set when Powertrain Control Module (PCM) attempts to regulate generator field with no result during monitoring. Possible causes are generator field resistance more than 5 ohms, open generator field driver circuit, generator field driver circuit shorted to ground, defective generator or PCM.

1. Turn ignition on. Using scan tool, actuate generator field driver circuit. Using a test light connected to ground, backprobe generator field driver circuit (Dark Green wire) on generator field connector terminal No. 2. (Scheme 1) If test light blinks, go to next step. If test light does not blink, go to step 4.
2. Wiggle wiring harness from generator to Powertrain Control Module (PCM). PCM is located in right rear of engine compartment. Using scan tool, read Diagnostic Trouble Codes (DTC) with actuator test still running. If generator field driver circuit DTC sets, repair wiring harness as necessary where wiggling caused problem to appear. Perform «CHARGING SYSTEM TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__charging-system-test) under VERIFICATION TESTS. If DTC does not set, go to next step.
3. Turn ignition off. Check all charging system related connectors for loose, corroded or damaged terminals. Repair as necessary. If no problem is found, test is complete.
4. Record all DTCs and clear codes. Check all charging system related connectors for loose, corroded or damaged terminals. Repair as necessary. Using scan tool, actuate generator field driver circuit. Using a voltmeter, measure voltage between ground and generator 2-pin connector field source terminal No. 1 (Light Blue/Red wire). If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair open in generator field source circuit between generator and PCM. Perform «CHARGING SYSTEM TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__charging-system-test) under VERIFICATION TESTS.
5. Turn ignition off. Disconnect PCM harness connectors. Disconnect field harness connector on rear of generator. Using an ohmmeter, measure resistance between PCM connector C2 terminal No. 10 generator field driver circuit (Dark Green wire) and ground. (Scheme 1), (Scheme 2) and (Scheme 3). If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground on Dark Green wire. Perform «CHARGING SYSTEM TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__charging-system-test) under VERIFICATION TESTS.
6. Measure resistance of Dark Green wire between PCM connector C2 terminal No. 10 and generator 2-pin connector terminal No. 2. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open generator field driver circuit. Perform «CHARGING SYSTEM TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__charging-system-test) under VERIFICATION TESTS.
7. Using an ohmmeter, measure resistance between generator field terminals on generator. If resistance is less than 5 ohms, replace generator. Perform «CHARGING SYSTEM TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__charging-system-test) under VERIFICATION TESTS. If resistance is 5 ohms or more, replace PCM.

Scheme 1

Scheme 2

Scheme 3

DTC P1492: BATTERY TEMPERATURE SENSOR VOLTAGE TOO HIGH

Note. Diagnostic Trouble Code (DTC) is set when ignition is on and Powertrain Control Module (PCM) senses Battery Temperature Sensor (BTS) voltage of more than 4.9 volts for more than 3 seconds. Possible causes are open BTS circuit, circuit short to voltage, BTS or PCM.

Cherokee

1. Turn ignition on. Using scan tool, check for DTCs. Check SPECIFIC GOOD TRIP counter for DTC P1492. If zero good trips are displayed (current problem), go to next step. If one or more good trips are displayed (problem not current), go to step 6.
2. Turn ignition off. Disconnect BTS connector. BTS is located in bottom of battery tray. Using an ohmmeter, measure resistance between BTS ground circuit terminal No. 2 (Brown/Yellow wire) and ground. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open on BTS ground circuit. Perform «ROAD TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__road-test) under VERIFICATION TESTS.
3. Start engine and allow engine to idle. Check voltage at BTS connector terminal No. 1 (Pink/Yellow wire). If voltage is 5.5 volts or less, go to next step. If voltage is more than 5.5 volts, repair short to voltage on BTS signal circuit. Perform «ROAD TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__road-test) under VERIFICATION TESTS.
4. Disconnect PCM connector C3. Leave BTS disconnected. Check resistance of Pink/Yellow wire between BTS connector terminal No. 1 and PCM connector C3 terminal No. 15. (Scheme 2) If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open on BTS signal circuit. Perform «ROAD TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__road-test) under VERIFICATION TESTS.
5. Turn ignition off. Turn ignition on. Using scan tool, select SENSORS. Monitor ambient battery temperature voltage. Using a jumper wire, connect BTS harness connector terminals together. Voltage should change from more than 4.5 volts to less than 1 volt. If voltage is as specified, replace BTS. Perform «ROAD TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__road-test) under VERIFICATION TESTS. If voltage is not as specified, replace PCM. Perform «ROAD TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__road-test) under VERIFICATION TESTS.
6. Check generator wiring, terminals and connectors. Start engine. Wiggle wiring harness from BTS to PCM. Using scan tool, read DTCs. If DTC sets, repair wiring harness as necessary where wiggling caused problem to appear. Perform «CHARGING SYSTEM TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__charging-system-test) under VERIFICATION TESTS. If no problem is found, test is complete.

Grand Cherokee & Wrangler

1. Turn ignition on. Using scan tool, check for DTCs. Check SPECIFIC GOOD TRIP counter for DTC P1492. If zero good trips are displayed (current problem), go to next step. If one or more good trips are displayed (problem not current), go to step 6.
2. Turn ignition off. Disconnect BTS connector. BTS is located in bottom of battery tray. Using an ohmmeter, measure resistance between BTS ground circuit terminal No. 1 (Black/Light Blue wire on Grand Cherokee), or terminal No. 2 (Black/Light Blue wire on Wrangler) and ground. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open on BTS ground circuit. Perform «ROAD TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__road-test) under VERIFICATION TESTS.
3. Disconnect PCM connector C3. Check resistance between BTS connector terminal No. 2 (Violet/Light Green wire on Grand Cherokee) or terminal No. 1 (Pink/Yellow wire on Wrangler) and PCM connector C3 terminal No. 15. (Scheme 2)and (Scheme 3). If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open on BTS signal circuit. Perform «ROAD TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__road-test) under VERIFICATION TESTS.
4. Start engine and allow engine to idle. Check voltage at BTS connector terminal No. 2 (Violet/Light Green wire on Grand Cherokee) or terminal No. 1 (Pink/Yellow wire on Wrangler). If voltage is 5.5 volts or less, go to next step. If voltage is more than 5.5 volts, repair short to voltage on BTS signal circuit. Perform «ROAD TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__road-test) under VERIFICATION TESTS.
5. Turn ignition off. Turn ignition on. Using scan tool, select SENSORS. Monitor ambient battery temperature voltage. Using a jumper wire, connect BTS harness connector terminals together. Voltage should change from more than 4.5 volts to less than 1 volt. If voltage is as specified, replace BTS. Perform «ROAD TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__road-test) under VERIFICATION TESTS. If voltage is not as specified, replace PCM. Perform «ROAD TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__road-test) under VERIFICATION TESTS.
6. Check generator wiring, terminals and connectors. Start engine. Wiggle wiring harness from BTS to PCM. Using scan tool, read DTCs. If DTC sets, repair wiring harness as necessary where wiggling caused problem to appear. Perform «CHARGING SYSTEM TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__charging-system-test) under VERIFICATION TESTS. If no problem is found, test is complete.

DTC P1493: BATTERY TEMPERATURE SENSOR VOLTAGE TOO LOW

Note. Diagnostic Trouble Code (DTC) is set when ignition is on and Powertrain Control Module (PCM) senses Battery Temperature Sensor (BTS) voltage of less than .5 volt for more than 3 seconds. Possible causes are BTS circuit shorted to ground, BTS or PCM.

1. Turn ignition on. Using scan tool, check for Diagnostic Trouble Codes (DTCs). Check SPECIFIC GOOD TRIP counter for DTC P1493. If zero good trips are displayed (current problem), go to next step. If one or more good trips are displayed (problem not current), go to step 5 .
2. Turn ignition on. Using scan tool, select SENSORS. Monitor ambient battery temperature voltage. Disconnect Battery Temperature Sensor (BTS) harness connector. Voltage should change from less than 1 volt to more than 4.5 volts. If voltage is not as specified, go to next step. If voltage is as specified, replace BTS. Perform «ROAD TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__road-test) under VERIFICATION TESTS.
3. Turn ignition off. Disconnect BTS connector. BTS is located in bottom of battery tray. Disconnect Powertrain Control Module (PCM) connector C3. Using an ohmmeter, check resistance between BTS signal circuit terminal No. 1 on Cherokee and Wrangler (Pink/Yellow wire), or terminal No. 2 on Grand Cherokee (Violet/Light Green wire) and ground. If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground on BTS signal circuit. Perform «ROAD TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__road-test) under VERIFICATION TESTS.
4. Check resistance between BTS harness connector terminals. If resistance is 5 ohms or more, replace PCM. Perform «ROAD TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__road-test) under VERIFICATION TESTS. If resistance is less than 5 ohms, repair short between BTS circuits. Perform «ROAD TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__road-test) under VERIFICATION TESTS.
5. Check generator wiring, terminals and connectors. Start engine. Wiggle wiring harness from BTS to PCM. Using scan tool, read DTCs. If DTC sets, repair wiring harness as necessary where wiggling caused problem to appear. Perform «CHARGING SYSTEM TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__charging-system-test) under VERIFICATION TESTS. If no problem is found, test is complete.

DTC P1594: CHARGING SYSTEM VOLTAGE TOO HIGH

Note. Diagnostic Trouble Code (DTC) is set when monitored battery voltage is one volt less than charging system upper limit threshold for 25 seconds. Powertrain Control Module (PCM) turns off field driver and monitors battery voltage. If voltage remains high, DTC P1594 is set. Possible causes are generator field driver circuit shorted to ground, shorted generator or PCM.

1. Ensure battery is fully charged, and generator belt tension and condition are okay. See «ADJUSTMENTS»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators). Turn ignition on. Using scan tool, actuate generator field driver. Using a voltmeter, measure voltage between ground and generator field connector terminal No. 2 (Dark Green wire). (Scheme 1) If voltage changes from low to high, go to next step. If voltage does not change from low to high, go to step 5.
2. Turn ignition on, with engine not running. Using scan tool, actuate generator field driver. Using scan tool, stop generator field driver actuation, then read target charging voltage. If target voltage is more than zero volts, go to next step. If target voltage is zero volts, go to step 4.
3. Start engine. Adjust engine speed to 1600 RPM. Using scan tool, read target charging voltage and actual voltage. Monitor readings for 5 minutes. If voltage readings remain within one volt of each other, go to next step. If voltage readings differ one volt or more, replace Powertrain Control Module (PCM). PCM is located in right rear of engine compartment. Perform «CHARGING SYSTEM TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__charging-system-test) under VERIFICATION TESTS.
4. Measure underhood temperature near battery using scan tool temperature probe. Using scan tool, read Battery Temperature Sensor (BTS) temperature. If scan tool display is within 10°F of actual underhood temperature, replace PCM. Perform «CHARGING SYSTEM TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__charging-system-test) under VERIFICATION TESTS. If scan tool display is not within 10°F of actual underhood temperature, replace BTS. Perform «CHARGING SYSTEM TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__charging-system-test) under VERIFICATION TESTS.
5. Turn ignition off. Disconnect PCM harness connectors. Disconnect field harness connector on rear of generator. Using an ohmmeter, measure resistance of generator field driver circuit between PCM connector C2 terminal No. 10 (Dark Green wire) and ground. (Scheme 2)and (Scheme 3). If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground on generator field driver circuit. Perform «CHARGING SYSTEM TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__charging-system-test) under VERIFICATION TESTS.
6. With generator field connector disconnected, measure resistance from either generator field terminal (on back of generator) to ground. (Scheme 1) If resistance is less than 5 ohms, replace shorted generator. If resistance is 5 ohms or more, replace PCM. Perform «CHARGING SYSTEM TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__charging-system-test) under VERIFICATION TESTS.

DTC P1682: CHARGING SYSTEM VOLTAGE TOO LOW

Note. Diagnostic Trouble Code (DTC) is set when monitored battery voltage is one volt less than charging system lower limit threshold for 25 seconds. Powertrain Control Module (PCM) turns on field driver and monitors battery voltage. If voltage remains low, DTC P1682 is set. Possible causes are open or high resistance in battery supply circuit between generator and battery, open field driver circuit, high resistance in ground circuit, defective generator or defective battery temperature sensor.

1. Ensure battery is fully charged. Check belt tension. See «ADJUSTMENTS»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators). Start engine. Using scan tool, read target charging voltage. If target charging voltage is more than 15.1 volts, go to next step. If target charging voltage is 15.1 volts or less, go to step 9.
2. Ensure engine is at normal operating temperature. Using scan tool, read Battery Temperature Sensor (BTS) temperature. Measure underhood temperature with a thermometer. If BTS temperature is not within 10°F of actual underhood temperature, go to next step. If BTS temperature is within 10°F of actual underhood temperature, go to step 9.
3. Turn ignition off. Disconnect BTS harness connector. BTS is mounted in bottom of battery tray. Connect jumper wire across BTS harness connector terminals. Turn ignition on. Using scan tool, read BTS voltage. If voltage is zero, replace BTS. Perform «ROAD TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__road-test) under VERIFICATION TESTS. If voltage is present, go to next step.
4. Record all DTCs. Erase all codes. Check all connectors and terminals for damage and corrosion. Repair any damage or corrosion as necessary. Using scan tool, actuate generator field. Using a voltmeter, measure voltage between ground and generator field source terminal (Dark Green/Orange wire on Cherokee, Light Blue/Red wire on Grand Cherokee or White/Dark Blue wire on Wrangler). (Scheme 1) If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair open circuit on field source wire between generator and PCM connector terminal No. 25. Perform «CHARGING SYSTEM TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__charging-system-test) under VERIFICATION TESTS.
5. Turn ignition off. Disconnect Power Control Module (PCM) harness connectors. Disconnect 2-pin generator field connector. Using ohmmeter, measure resistance of Dark Green wire between PCM harness connector C2 terminal No. 10 and 2-pin generator field harness connector terminal No. 2. (Scheme 2)or (Scheme 3). If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open field source circuit. Perform «CHARGING SYSTEM TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__charging-system-test) under VERIFICATION TESTS.
6. Using an ohmmeter, measure resistance between ground and PCM harness connector C3 generator field source terminal No. 25 (Dark Green/Orange wire on Cherokee, Light Blue/Red wire on Grand Cherokee or White/Dark Blue wire on Wrangler). If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair field source circuit for short to ground and replace PCM. Perform «CHARGING SYSTEM TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__charging-system-test) under VERIFICATION TESTS.
7. Using an ohmmeter, measure resistance between ground and PCM harness connector C2 generator field driver terminal No. 10 (Dark Green wire). If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair field driver circuit for short to ground. Perform «CHARGING SYSTEM TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__charging-system-test) under VERIFICATION TESTS.
8. Turn ignition off. Connect 2-pin generator field harness connector. Connect a voltmeter between generator case and battery negative terminal. Start and warm engine to operating temperature. If voltage is.1 volt or less, go to step 17. If voltage is more than.1 volt, repair generator ground for high resistance between generator case and battery negative terminal. Perform «CHARGING SYSTEM TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__charging-system-test) under VERIFICATION TESTS.
9. Turn ignition on. Connect a voltmeter between generator B+ terminal and battery positive terminal. (Scheme 1) Start engine. If voltage is.4 volt or less, go to next step. If voltage is more than.4 volt, repair B+ circuit for high resistance between generator and battery. Perform «CHARGING SYSTEM TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__charging-system-test) under VERIFICATION TESTS.
10. Ensure engine is at operating temperature. Connect a voltmeter between generator case and battery negative terminal. Start engine. If voltage is.1 volt or less, go to next step. If voltage is more than.1 volt, repair generator ground for high resistance between generator case and battery negative terminal. Perform «CHARGING SYSTEM TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__charging-system-test) under VERIFICATION TESTS.
11. Turn off all accessories. Set engine speed to 1600 RPM. Using scan tool, read target charging voltage and charging voltage. If readings differ by more than one volt, go to next step. If both readings are within one volt, test is complete.
12. Turn ignition off. Turn ignition on. Using scan tool, actuate generator field. Check voltage at both generator field terminals. (Scheme 1) If voltage is less than 3 volts at either terminal, go to next step. If voltage at both terminals is more than 3 volts, test is complete.
13. Record all DTCs. Erase all codes. Check all connectors and terminals for damage and corrosion. Repair any damage or corrosion as necessary. Using scan tool, actuate generator field. Using a voltmeter, measure voltage between ground and generator field source terminal (Dark Green/Orange wire on Cherokee, Light Blue/Red wire on Grand Cherokee or White/Dark Blue wire on Wrangler). If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair open circuit on field source wire between generator and PCM connector terminal No. 25. Perform «CHARGING SYSTEM TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__charging-system-test) under VERIFICATION TESTS.
14. Turn ignition off. Disconnect PCM harness connectors. Using an ohmmeter, measure resistance between ground and PCM harness connector C2 generator field driver terminal No. 10 (Dark Green wire). (Scheme 2)or (Scheme 3). If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair short to ground inDark Green wire. Perform «CHARGING SYSTEM TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__charging-system-test) under VERIFICATION TESTS.
15. Disconnect 2-pin generator field connector. Using an ohmmeter, measure resistance of Dark Green wire between PCM harness connector C2 generator field driver terminal No. 10 and generator field harness connector terminal No. 2. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open field circuit. Perform «CHARGING SYSTEM TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__charging-system-test) under VERIFICATION TESTS.
16. Using an ohmmeter, measure resistance between ground and PCM harness connector C3 generator field source terminal No. 25 (Dark Green/Orange wire on Cherokee, Light Blue/Red wire on Grand Cherokee or White/Dark Blue wire on Wrangler). If resistance is 5 ohms or more, go to next step. If resistance is less than 5 ohms, repair field source circuit for short to ground and replace PCM. Perform «CHARGING SYSTEM TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__charging-system-test) under VERIFICATION TESTS.
17. If no other problems were found, replace PCM. Perform «CHARGING SYSTEM TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__charging-system-test) under VERIFICATION TESTS.

CHARGING SYSTEM NO CODE TEST

1. Verify battery condition. Charge or replace battery as necessary. Inspect generator belt tension and condition. See «ADJUSTMENTS»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators). Replace generator belt as necessary. Start engine. Turn on all accessories. Set engine speed to 2000 RPM for 30 seconds, then return to idle. Using scan tool, check for Diagnostic Trouble Codes (DTCs). See «DIAGNOSTIC TROUBLE CODE IDENTIFICATION»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators) table under SELF-DIAGNOSTIC SYSTEM. If any charging system DTCs are set, perform appropriate test under «DIAGNOSTIC TESTS»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators). If no charging system DTCs are set, go to next step.
2. Turn ignition on, with engine off. Using scan tool, actuate generator field. Using test light, backprobe generator field driver terminal No. 2 (Dark Green wire). (Scheme 1) Test light should flash on and off every 1.4 seconds. While observing test light, wiggle field terminal wiring harness back to Powertrain Control Module (PCM). If any interruption of voltage cycling occurred, repair wiring harness where wiggling caused failure. Perform «CHARGING SYSTEM TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__charging-system-test) under VERIFICATION TESTS. If wiggling did not interrupt voltage cycling, go to next step.
3. Read DTCs. See «DIAGNOSTIC TROUBLE CODE IDENTIFICATION»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators) table under SELF-DIAGNOSTIC SYSTEM. If any charging system DTCs are set, perform appropriate test under «DIAGNOSTIC TESTS»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators). If no charging system DTCs are set, go to next step.
4. Turn ignition on. Using a voltmeter, check voltage between generator B+ terminal located on rear of generator and battery positive terminal. Ensure voltmeter wires are clear of moving engine parts. Start engine and observe voltmeter. If voltage is.4 volt or less, go to next step. If voltage is more than.4 volt, repair high resistance between generator B+ terminal and battery positive terminal. Perform «CHARGING SYSTEM TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__charging-system-test) under VERIFICATION TESTS.
5. Ensure engine is running. Using a voltmeter, check voltage between generator case and battery negative terminal. If voltage is.1 volt or less, go to next step. If voltage is more than.1 volt, repair high resistance between generator and battery negative terminal. Perform «CHARGING SYSTEM TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__charging-system-test) under VERIFICATION TESTS.
6. Check voltage between battery terminals. Check voltage between battery cables. If difference between voltage readings is one volt or more, go to next step. If difference between voltage readings is less than one volt, test is complete.
7. Turn ignition on. Using scan tool, read and record battery voltage. Turn ignition off. Disconnect PCM connectors. Turn ignition on. Using a voltmeter, check voltage at PCM harness connector C1 terminal No. 22 (Dark Green/Black wire on Cherokee, Red/Black wire on Grand Cherokee and Red/White wire on Wrangler). (Scheme 2)or (Scheme 3). If difference between voltage readings is less than one volt, replace PCM. Perform «CHARGING SYSTEM TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__charging-system-test) under VERIFICATION TESTS. If difference between voltage readings is one volt or more, repair high resistance between PCM and battery. Perform «CHARGING SYSTEM TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__charging-system-test) under VERIFICATION TESTS.

BATTERY TEMPERATURE SENSOR (BTS) NO CODE TEST

1. Ensure engine is at normal operating temperature. Using scan tool, read Battery Temperature Sensor (BTS) temperature. Measure underhood temperature with a thermometer. If BTS temperature is not within 10°F of actual underhood temperature, go to next step. If BTS temperature is within 10°F of actual underhood temperature, go to next step.
2. Turn ignition off. Disconnect BTS harness connector. BTS is mounted in bottom of battery tray. Connect jumper wire across BTS harness connector terminals. Turn ignition on. Using scan tool, read BTS voltage. If voltage is zero, replace BTS. Perform «ROAD TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__road-test) under VERIFICATION TESTS. If voltage is present, test is complete.

TEST VER-2

Note. If replacing Powertrain Control Module (PCM), the correct vehicle mileage and Vehicle Identification Number (VIN) must be programmed into PCM to prevent Diagnostic Trouble Codes (DTC) from being stored in Anti-Lock Brake System (ABS) module and Air Bag Control Module (ACM). If replacing PCM and vehicle is equipped with a Smart Key Immobilizer Module (SKIM), secret key data must also be updated to enable engine starting.

1. Inspect vehicle to ensure all engine components are connected. Reassemble and reconnect components as necessary. If test is being performed after performing a repair that did not involve a Diagnostic Trouble Code (DTC) test, go to next step. If test is being performed after performing a repair that involved a DTC test, go to step 3 .
2. Check if initial symptom still exists. If initial or another symptom exists, repair is not complete. Check for Technical Service Bulletins (TSBs) that apply to symptom. Go to «ON-VEHICLE TESTING»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__on-vehicle-testing) for diagnosis by symptom. If initial symptom no longer exists and no DTCs are present, test is complete.
3. If repair procedure did not include replacing PCM, go to next step. If PCM has been replaced and has already been programmed, go to next step. If PCM has been replaced but has not been programmed, connect scan tool to Data Link Connector (DLC). DLC is located below driver's side of instrument panel. Using scan tool, enter correct VIN and mileage into PCM. Using scan tool manufacturer's instructions, clear DTCs from ABS and SRS modules. For more information, see PROGRAMMING in SYSTEM & COMPONENT TESTING article in ENGINE PERFORMANCE. After PCM is programmed, go to next step.
4. Road test vehicle for at least 5 minutes. If repair involved A/C relay control circuit, ensure A/C is on during road test. Road test vehicle at a speed of at least 40 MPH at some point during road test. Stop vehicle. Turn engine off for at least 10 seconds. Start engine and continue road test. Ensure transmission shifts through all gears. After road test, turn engine off and go to next step.
5. Recheck for DTCs. If any DTCs exist, diagnose and repair as necessary. If no DTCs exist, repair is complete.

CHARGING SYSTEM TEST

1. Inspect vehicle to ensure all engine components are connected. Reassemble and reconnect components as necessary. Connect scan tool to Data Link Connector (DLC). DLC is located below driver's side of instrument panel. Clear all DTCs. If PCM has been replaced, go to next step. If PCM was not replaced, go to step 3 .
2. Using scan tool, enter correct VIN and mileage into PCM. Using scan tool manufacturer's instructions, clear DTCs from ABS and SRS modules. For more information, see PROGRAMMING in SYSTEM & COMPONENT TESTING article in ENGINE PERFORMANCE. After PCM is programmed, go to next step.
3. Start engine. Check charging system voltage output. See «OUTPUT VOLTAGE TEST»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__output-voltage-test) under ON-VEHICLE TESTING. Adjust engine speed to 2000 RPM for 30 seconds. Allow engine to idle. Turn ignition off. Turn ignition on. Using scan tool, check for DTCs. If any DTCs exist, diagnose and repair as necessary. See «DIAGNOSTIC TROUBLE CODE IDENTIFICATION»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators) table under SELF-DIAGNOSTIC SYSTEM. If no DTCs exist, repair is complete.

ROAD TEST

1. Inspect vehicle to ensure all engine components are connected. Reassemble and reconnect components as necessary. Connect scan tool to Data Link Connector (DLC). DLC is located below driver's side of instrument panel. Clear all DTCs. Ensure fuel tank is at least 25 percent full. If PCM has been replaced, go to next step. If PCM was not replaced, go to step 3 .
2. Using scan tool, enter correct VIN and mileage into PCM. Using scan tool manufacturer's instructions, clear DTCs from ABS and SRS modules. For more information, see PROGRAMMING in SYSTEM & COMPONENT TESTING article in ENGINE PERFORMANCE. After PCM is programmed, go to next step.
3. If any DTCs have not been diagnosed, go to appropriate test and finish diagnosing remaining DTCs as necessary. See «DIAGNOSTIC TROUBLE CODE IDENTIFICATION»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators) table under SELF-DIAGNOSTIC SYSTEM. If all DTCs have been diagnosed, go to next step.
4. Using scan tool OBDII monitor, verify DTC repair. See scan tool instructions. Allow PCM to run appropriate monitor(s) and increment a GOOD TRIP (drive cycle). Enabling conditions must be met before PCM will run OBDII monitor. Scan tool monitor pretest screen will display enabling conditions.
5. If repaired DTC has reset or was seen in OBDII monitor while on road test, repair is not complete. Check for any technical service bulletins and return to appropriate test. Repair as needed.
6. If any other DTCs are set, repair as needed. See «DIAGNOSTIC TROUBLE CODE IDENTIFICATION»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators) table under SELF-DIAGNOSTIC SYSTEM. If OBDII monitor is run and GOOD TRIP counter is incremented and no new DTCs are set, repair is successful and complete. Erase DTCs. See «CLEARING DIAGNOSTIC TROUBLE CODES»(/jeep/grand-cherokee/wj-1998-2004/remont/charging-system/#charging-system-generators-regulators__clearing-diagnostic-trouble-codes) under SELF-DIAGNOSTIC SYSTEM.

BENCH TESTING

Note. Generator is not serviceable. Replace generator if defective.

TORQUE SPECIFICATIONS

TORQUE SPECIFICATIONS

Charging System Wiring Diagram (Cherokee). Scheme 4

Charging System Wiring Diagram (Grand Cherokee). Scheme 5

Charging System Wiring Diagram (Wrangler). Scheme 6

See also:
• BELT ADJUSTMENT
• TORQUE SPECIFICATIONS
• VOLTAGE DROP TEST
• SELF-DIAGNOSTIC SYSTEM
• CLEARING DIAGNOSTIC TROUBLE CODES
• INITIAL CHECKS
• ON-VEHICLE TESTING
• CHARGING SYSTEM NO CODE TEST
• P0622
• P1492
• P1493
• P1594
• P1682
• CHARGING SYSTEM TEST
• ROAD TEST
• OUTPUT VOLTAGE TEST