Control Circuit Test

CONTROL CIRCUIT TEST

The starter control circuit has:

- Starter motor with integral solenoid
- Starter relay
- Body Control Module (BCM)
- Ignition switch
- Battery
- All related wiring and connections
- Powertrain Control Module (PCM)
- Starter Button

CAUTION: Before performing any starter tests, the ignition and fuel systems must be disabled.

- To disable ignition and fuel systems, disconnect the Automatic Shutdown Relay (ASD). The ASD relay is located in the Power Distribution Center (PDC). Refer to the PDC cover for the proper relay location.

STARTER SOLENOID

WARNING: CHECK TO ENSURE THAT THE TRANSMISSION IS IN THE PARK POSITION WITH THE PARKING BRAKE APPLIED.

1. Verify battery condition. Battery must be in good condition with a full charge before performing any starter tests. Refer to Battery Tests.
2. Perform Starter Solenoid test BEFORE performing the starter relay test.
3. Perform a visual inspection of the starter/starter solenoid for corrosion, loose connections or faulty wiring.
4. Locate and remove the starter relay from the Power Distribution Center (PDC). Refer to the PDC label for relay identification and location.
5. Connect a remote starter switch or a jumper wire between the remote battery positive post and terminal 87 of the starter relay connector.
a. If engine cranks, starter/starter solenoid is good. Go to the Starter Relay Test.
b. If engine does not crank or solenoid chatters, check wiring and connectors from starter relay to starter solenoid for loose or corroded connections. Particularly at starter terminals.
c. Repeat test. If engine still fails to crank properly, trouble is within starter or starter mounted solenoid, and replace starter. Inspect the ring gear teeth.

STARTER RELAY

WARNING: CHECK TO ENSURE THAT THE TRANSMISSION IS IN NEUTRAL POSITION WITH THE PARKING BRAKE APPLIED.

RELAY TEST

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

Remove the starter relay from the PDC as described to perform the following tests:

1. A relay in the de-energized position should have continuity between terminals 87A and 30, and no continuity between terminals 87 and 30. If OK, go to 2. If not OK, replace the faulty relay.
2. Resistance between terminals 85 and 86 (electromagnet) should be 75 ±5 ohms. If OK, go to 3. If not OK, replace the faulty relay.
3. Connect a battery B+ lead to terminals 86 and a ground lead to terminal 85 to energize the relay. The relay should click. Also test for continuity between terminals 30 and 87, and no continuity between terminals 87A and 30. If OK, refer to Relay Circuit Test procedure. If not OK, replace the faulty relay.













RELAY CIRCUIT TEST

1. The relay common feed terminal cavity (30) is connected to battery voltage and should be hot at all times. If OK, go to 2. If not OK, repair the open circuit to the PDC fuse as required.
2. The relay normally closed terminal (87A) is connected to terminal 30 in the de-energized position, but is not used for this application. Go to 3.
3. The relay normally open terminal (87) is connected to the common feed terminal (30) in the energized position. This terminal supplies battery voltage to the starter solenoid field coils. There should be continuity between the cavity for relay terminal 87 and the starter solenoid terminal at all times. If OK, go to 4. If not OK, repair the open circuit to the starter solenoid as required.
4. The coil battery terminal (86) is connected to the electromagnet in the relay. It is energized when the ignition switch is held in the ON position after depressing the clutch pedal. Check for battery voltage at the cavity for relay terminal 86 with the ignition switch in the ON position and push the start button after depressing the clutch pedal. If OK, go to 5. If not OK, check for an open or short circuit to the ignition switch and repair, if required. If the circuit to the ignition switch is OK, see the Ignition Switch Test procedure.
5. The coil ground terminal (85) is connected to the electromagnet in the relay. It is grounded through the PCM. Check for continuity between the PCM and cavity for relay terminal 85.

SAFETY SWITCHES

If diagnostics of the Clutch Interlock/Upstop Switch, refer to Diagnosis and Testing in Clutch.

IGNITION SWITCH

After testing starter solenoid and relay, test ignition switch and wiring. Check all wiring for opens or shorts, and all connectors for being loose or corroded.

STARTER BUTTON

Check starter button and wiring. Check all wiring for opens or shorts, and all connectors for being loose or corroded.

BATTERY

For battery diagnosis and testing, refer to Battery for procedures.

ALL RELATED WIRING AND CONNECTORS

Refer to Wiring Diagrams for more information.