Starting System: Diagnosis Jeep Cherokee III

TROUBLE SHOOTING

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

If starter does not operate, check battery condition and charge. Check fuses, wiring and connections. Check starter relay, ignition switch, Clutch Pedal Position (CPP) switch (M/T) or Park/Neutral Position (PNP) switch (A/T). Check starter solenoid and starter.

If starter engages, but does not turn engine, Check battery condition and charge. Check starting circuit and starter. Check engine for seized condition.

If starter engages, but disengages before engine starts, check starter ring gear and starter motor.

If starter does not disengage, check starter installation, starter relay, ignition switch and starter motor.

ON-VEHICLE TESTING

CRANKING TEST

Note. Ensure engine is at normal operating temperature. High viscosity oil, extreme cold temperatures, or tight piston ring-to-cylinder wall clearance will increase amperage draw.

1. Using a battery load tester, connect positive and negative leads to battery. Connect inductive ammeter pick-up to positive battery cable. Ensure all lights and accessories are off. Place A/T in Park, or M/T in Neutral. Apply parking brake. Remove Automatic Shutdown (ASD) relay from Power Distribution Center (PDC). Refer to PDC cover for relay location. PDC is located in engine compartment. On M/T models, depress clutch pedal. CAUTION: During cranking, DO NOT draw battery voltage down to less than 9.6 volts. Use care not to overheat starter.
2. On all models, crank engine and observe voltmeter reading. If voltage drops to less than 9.6 volts, recharge and test battery. Retest voltage. If voltage remains at less than 9.6 volts, bench test starter. See «BENCH TESTING»(ref-91677-S16895541972001032700000) . If voltage remains more than 9.6 volts, observe amperage reading. If amperage draw is less than specified, perform circuit resistance tests. See «STARTER SPECIFICATIONS»(ref-91677-S33534801242001032700000) . Also see «FEED CIRCUIT RESISTANCE TESTS»(ref-91677-S00306519872001032700000) .
3. If voltage reads more than 12.5 volts, and starter does not turn, problem is in battery, starter relay, starter solenoid, ignition switch, Park/Neutral Position (PNP) switch, Clutch Pedal Position (CPP) switch or wiring. Check each component until problem is found. If voltage is more than 12.5 volts and starter cranks very slowly, perform circuit resistance tests. See «FEED CIRCUIT RESISTANCE TESTS»(ref-91677-S00306519872001032700000) .

Battery Connection Resistance Test

Connect voltmeter positive lead to negative battery cable clamp. Connect voltmeter negative lead to negative battery post. Crank engine and observe voltmeter reading. If voltage is greater than 0.2 volt, repair poor contact between cable clamp and post. Perform same procedure to positive battery post and cable clamp.

Positive Battery Cable Resistance Test

1. Remove starter heat shield (if equipped) to gain access to starter solenoid connections. Connect voltmeter negative lead to starter solenoid battery terminal and voltmeter positive lead to positive battery post.
2. Crank engine and observe voltmeter reading. If voltage reads more than 0.2 volt, correct poor connection between battery cable and starter solenoid or replace positive battery cable.

Ground Connection Resistance Test

Connect voltmeter negative lead to negative battery post. Connect voltmeter positive lead to engine block, near negative battery cable grounding point. Crank engine and observe voltmeter reading. If voltage is greater than 0.2 volt, repair poor ground connection or replace ground cable.

Starter Ground Connection Resistance Test

Connect voltmeter negative lead to negative battery post. Connect voltmeter positive lead to starter housing. Crank engine and observe voltmeter reading. If voltmeter reading indicates more than 0.2 volt, repair poor starter-to-ground connection.

SOLENOID CIRCUIT TEST

Note. Perform this procedure before testing starter relay circuit and starter relay. Ensure vehicle is in Park (A/T) or Neutral (M/T) and parking brake is applied.

1. Ensure battery is fully charged. Ensure solenoid connections are not loose or corroded. Remove starter relay from Power Distribution Center (PDC). Refer to PDC cover for proper relay location. PDC is located in engine compartment.
2. Connect a remote starter switch or jumper wire between starter relay connector terminal C9 (Cherokee), No. 87 (Grand Cherokee) or B2 (Wrangler) and positive battery post. see scheme 1, see scheme 2 or see scheme 3. If engine cranks, solenoid and starter are good. Go to «STARTER RELAY CIRCUIT TEST»(ref-91677-S24316779872001032700000).
3. If engine fails to crank, or if solenoid chatters, check wiring and connectors from starter relay connector to starter solenoid terminal for loose or corroded connections. Clean and retest. If engine still fails to crank, remove starter and proceed to «SOLENOID TEST»(ref-91677-S14555411962001032700000) under BENCH TESTING.

STARTER RELAY CIRCUIT TEST

Note. Perform SOLENOID CIRCUIT TEST before testing starter relay circuit.

IGNITION SWITCH TEST

1. Disconnect negative battery cable. Remove ignition switch. See appropriate STEERING COLUMN SWITCHES article in ACCESSORIES & EQUIPMENT. With ignition switch in ON position, check for continuity between ignition switch terminals. See «IGNITION SWITCH CONTINUITY»(ref-91677-S02210194402001032700000) table. (Scheme 2)or (Scheme 1). If continuity does not exist, replace ignition switch. If continuity exists, go to next step.
2. With ignition switch in START position, check for continuity between specified ignition switch terminals. See «IGNITION SWITCH CONTINUITY»(ref-91677-S02210194402001032700000) table. If continuity exists at all measurements, ignition switch is okay. If continuity does not exist at any or all measurements, replace ignition switch.

IGNITION SWITCH CONTINUITY

Scheme 1

Scheme 2

SOLENOID TEST

Remove starter. Using DVOM, check for continuity between field terminal (large terminal connected to starter body) and solenoid terminal (smallest terminal). Check for continuity between solenoid terminal and solenoid housing. Continuity should exist. If continuity does not exist in either test, solenoid has open circuit. Replace starter assembly.