Charging System - Generators & Regulators: Diagnosis Jeep Cherokee III

TROUBLE SHOOTING

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

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»(ref-91694-S10160436522001032800000) .
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»(ref-91694-S10160436522001032800000) . If voltage tests are as specified, reduce engine speed, and turn off blower motor, headlights and ignition switch.

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 .

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»(ref-91694-S03328021852001032800000) .
2. If DTCs are displayed, see «DIAGNOSTIC TROUBLE CODE IDENTIFICATION»(ref-91694-S29612232002001032800000) 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»(ref-91694-S17344876722001032800000) 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.

CHARGING SYSTEM NO CODE TEST

1. Verify battery condition. Charge or replace battery as necessary. Inspect generator belt tension and condition. See «ADJUSTMENTS»(ref-91694-S17264980932001032800000). 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»(ref-91694-S29612232002001032800000) table under SELF-DIAGNOSTIC SYSTEM. If any charging system DTCs are set, perform appropriate test under «DIAGNOSTIC TESTS»(ref-91694-S12010638782001032800000). 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). (Схема №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»(ref-91694-S29359334762001032800000) under VERIFICATION TESTS. If wiggling did not interrupt voltage cycling, go to next step.
3. Read DTCs. See «DIAGNOSTIC TROUBLE CODE IDENTIFICATION»(ref-91694-S29612232002001032800000) table under SELF-DIAGNOSTIC SYSTEM. If any charging system DTCs are set, perform appropriate test under «DIAGNOSTIC TESTS»(ref-91694-S12010638782001032800000). 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»(ref-91694-S29359334762001032800000) 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»(ref-91694-S29359334762001032800000) 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). (Схема №2)or (Схема №3). If difference between voltage readings is less than one volt, replace PCM. Perform «CHARGING SYSTEM TEST»(ref-91694-S29359334762001032800000) under VERIFICATION TESTS. If difference between voltage readings is one volt or more, repair high resistance between PCM and battery. Perform «CHARGING SYSTEM TEST»(ref-91694-S29359334762001032800000) 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»(ref-91694-S41116950642001032800000) 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»(ref-91694-S19913164312001032800000) 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»(ref-91694-S12118667412001032800000) 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»(ref-91694-S29612232002001032800000) 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»(ref-91694-S29612232002001032800000) 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»(ref-91694-S29612232002001032800000) 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»(ref-91694-S28344683702001032800000) under SELF-DIAGNOSTIC SYSTEM.

BENCH TESTING

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