Starting System: Other Jeep Liberty I

STARTER MOTOR RELAY

The starter relay is an electromechanical device that switches battery current to the pull-in coil of the starter solenoid when ignition switch is turned to Start position. The starter relay is located in the Power Distribution Center (PDC) in the engine compartment. See PDC cover for relay identification and location.

The starter relay is a International Standards Organization (ISO) relay. Relays conforming to ISO specifications have common physical dimensions, current capacities, terminal patterns, and terminal functions.

The starter relay cannot be repaired or adjusted and, if faulty or damaged, it must be replaced.

The starting system components form two separate circuits. A high-amperage feed circuit that feeds the starter motor between 150 and 350 amperes (700 amperes - diesel engine), and a low-amperage control circuit that operates on less than 20 amperes. The high-amperage feed circuit components include the battery, the battery cables, the contact disc portion of the starter solenoid, and the starter motor. The low-amperage control circuit components include the ignition switch, the clutch pedal position switch (manual transmission), the park/neutral position switch (automatic transmission), the starter relay, the electromagnetic windings of the starter solenoid, and the connecting wire harness components.

If the vehicle is equipped with a manual transmission, it has a clutch pedal position switch installed in series between the ignition switch and the coil battery terminal of the starter relay. This normally open switch prevents the starter relay from being energized when the ignition switch is turned to the momentary Start position, unless the clutch pedal is depressed. This feature prevents starter motor operation while the clutch disc and the flywheel are engaged. The starter relay coil ground terminal is always grounded on vehicles with a manual transmission.

If the vehicle is equipped with an automatic transmission, battery voltage is supplied through the low-amperage control circuit to the coil battery terminal of the starter relay when the ignition switch is turned to the momentary Start position. The park/neutral position switch is installed in series between the starter relay coil ground terminal and ground. This normally open switch prevents the starter relay from being energized and the starter motor from operating unless the automatic transmission gear selector is in the Neutral or Park positions.

When the starter relay coil is energized, the normally open relay contacts close. The relay contacts connect the relay common feed terminal to the relay normally open terminal. The closed relay contacts energize the starter solenoid coil windings.

The energized solenoid pull-in coil pulls in the solenoid plunger. The solenoid plunger pulls the shift lever in the starter motor. This engages the starter overrunning clutch and pinion gear with the starter ring gear on the manual transmission flywheel or on the automatic transmission torque converter or torque converter drive plate.

As the solenoid plunger reaches the end of its travel, the solenoid contact disc completes the high-amperage starter feed circuit and energizes the solenoid plunger hold-in coil. Current now flows between the solenoid battery terminal and the starter motor, energizing the starter.

Once the engine starts, the overrunning clutch protects the starter motor from damage by allowing the starter pinion gear to spin faster than the pinion shaft. When the driver releases the ignition switch to the On position, the starter relay coil is de-energized. This causes the relay contacts to open. When the relay contacts open, the starter solenoid plunger hold-in coil is de-energized.

When the solenoid plunger hold-in coil is de-energized, the solenoid plunger return spring returns the plunger to its relaxed position. This causes the contact disc to open the starter feed circuit, and the shift lever to disengage the overrunning clutch and pinion gear from the starter ring gear.

The ISO relay consists of an electromagnetic coil, a resistor or diode, and three (two fixed and one movable) electrical contacts. The movable (common feed) relay contact is held against one of the fixed contacts (normally closed) by spring pressure. When electromagnetic coil is energized, it draws the movable contact away from normally closed fixed contact, and holds it against the other (normally open) fixed contact.

When electromagnetic coil is de-energized, spring pressure returns movable contact to normally closed position. The resistor or diode is connected in parallel with electromagnetic coil within relay, and helps to dissipate voltage spikes produced when coil is de-energized.

PRELIMINARY CHECKS

The battery, starting, and charging systems operate in conjunction with one another, and must be tested as a complete system. For correct starting/charging system operation, all of the components involved in these 3 systems must perform within specifications.

The following starting system components should be carefully inspected whenever any starting system problem is encountered.

Battery

1. Visually inspect battery for indications of physical damage and loose or corroded cable connections. Determine state-of-charge and cranking capacity of battery. Charge or replace battery, if required.

Ignition Switch

1. Visually inspect ignition switch for indications of physical damage and loose or corroded wire harness connections. Clean corroded connections as required. See appropriate article under «WIRING DIAGRAMS»(ref-164343-S12266741212004080200000) .

Clutch Pedal Position Switch

1. If vehicle is equipped with a manual transmission, visually inspect clutch pedal position switch for indications of physical damage and loose or corroded wire harness connections. Clean corroded connections as required.

Park/Neutral Position Switch

1. If vehicle is equipped with an automatic transmission, visually inspect park/neutral position switch for indications of physical damage and loose or corroded wire harness connections. Clean corroded connections as required.

Starter Relay

1. Visually inspect starter relay for indications of physical damage and loose or corroded wire harness connections. Clean corroded connections as required.

Starter Motor

1. Visually inspect starter motor for indications of physical damage and loose or corroded wire harness connections. Clean corroded connections as required. If problem being diagnosed involved improper starter engagement, disengagement or noise complaints, starter motor should be removed. With starter motor removed, inspect starter pinion and ring gears for damaged or missing teeth. Replace faulty components as required.

Starter Solenoid

1. Visually inspect starter solenoid for indications of physical damage and loose or corroded wire harness connections. Clean corroded connections as required.

STARTER FAILS TO OPERATE

1. Battery Discharged Or Faulty: Test and replace if necessary
2. Starting Circuit Wiring Faulty: Test and repair if required. See «WIRING DIAGRAMS»(ref-164343-S12266741212004080200000) .
3. Starter Relay Faulty: Test and replace if required. See «STARTER RELAY»(ref-164343-S40725808752004080200000) under COMPONENT TESTING.
4. Ignition Switch Faulty: Test and replace if required
5. Clutch Pedal Position Switch Faulty
6. Park/Neutral Position Switch Faulty Or Misadjusted: Replace if required
7. Starter Solenoid Faulty: See «STARTER SOLENOID»(ref-164343-S17783190312004080200000) under COMPONENT TESTING. Replace if required
8. Starter Motor Faulty: See «STARTER MOTOR»(ref-164343-S04509724852004080200000) under COMPONENT TESTING.

STARTER ENGAGES, FAILS TO TURN ENGINE

1. Battery Discharged Or Faulty: Charge and replace if necessary
2. Starting Circuit Wiring Faulty: Test and repair if required. See «WIRING DIAGRAMS»(ref-164343-S12266741212004080200000) .
3. Starter Motor Faulty: See «STARTER MOTOR»(ref-164343-S04509724852004080200000) under COMPONENT TESTING.
4. Engine Seized: See appropriate article in ENGINES.

STARTER ENGAGES, SPINS OUT BEFORE ENGINE STARTS

1. Starter Ring Gear Faulty: Remove and replace if required
2. Starter Motor Faulty: See «STARTER MOTOR»(ref-164343-S04509724852004080200000) under COMPONENT TESTING.

STARTER DOES NOT DISENGAGE

1. Starter Motor Improperly Installed: See «REMOVAL & INSTALLATION»(ref-164343-S00636642732004080200000) use «TORQUE SPECIFICATIONS»(ref-164343-S29374494272004080200000) .
2. Starter Relay Faulty: Test and replace if required. See «STARTER RELAY»(ref-164343-S40725808752004080200000) under COMPONENT TESTING.
3. Ignition Switch Faulty: Replace if required
4. Starter Motor Faulty: check components, if OK, then replace starter motor. See «STARTER MOTOR»(ref-164343-S04509724852004080200000) under COMPONENT TESTING.

Correct starter motor operation can be confirmed by performing the following free running bench test. This test can only be performed with starter motor removed from vehicle. Refer to Specifications for starter motor specifications.

1. Remove starter motor from vehicle.
2. Mount starter motor securely in a soft-jawed bench vise. The vise jaws should be clamped on the mounting flange of starter motor. Never clamp on starter motor by field frame.
3. Connect a suitable volt-ampere tester and a 12-volt battery to starter motor in series, and set ammeter to 100 ampere scale. See instructions provided by manufacturer of volt-ampere tester being used.
4. Install jumper wire from solenoid terminal to solenoid battery terminal. The starter motor should operate. If starter motor fails to operate, replace faulty starter motor assembly.
5. Adjust carbon pile load of tester to obtain free running test voltage. Refer to Specifications for starter motor free running test voltage specifications.
6. Note reading on ammeter and compare reading to free running test maximum amperage draw. Refer to Specifications for starter motor free running test maximum amperage draw specifications.
7. If ammeter reading exceeds maximum amperage draw specification, replace faulty starter motor assembly.

This test can only be performed with starter motor removed from vehicle.

Scheme 13

1. Remove starter motor from vehicle. Refer to Starter Motor Removal and Installation.
2. Disconnect wire from solenoid field coil terminal.
3. Check for continuity between solenoid terminal and solenoid field coil terminal with a continuity tester. (Scheme 13) There should be continuity. If OK, go to Step 4. If not OK, replace faulty starter motor assembly.
4. Check for continuity between solenoid terminal and solenoid case. (Scheme 14) There should be continuity. If not OK, replace faulty starter motor assembly.

Scheme 14

The starter relay is located in the Power Distribution Center (PDC) in engine compartment. Refer to label on PDC cover for relay location.

1. Remove starter relay from PDC. see scheme 7
2. A relay in de-energized position should have continuity between terminals 87A and 30, and no continuity between terminals 87 and 30. If OK, go to Step 3. If not OK, replace faulty relay.
3. Resistance between terminals 85 and 86 (electromagnet) should be 75 +/- 5 ohms. If OK, go to Step 4. If not OK, replace faulty relay.
4. Connect a battery to terminals 85 and 86. There should now be continuity between terminals 30 and 87, and no continuity between terminals 87A and 30. If OK, perform following Relay Circuit Test. If not OK, replace faulty relay.

2003

For starter wiring see STARTING/CHARGING in SYSTEM WIRING DIAGRAMS article.

2004

For starter wiring see STARTING/CHARGING in SYSTEM WIRING DIAGRAMS article.