The starting system consists of an ignition switch, starter relay, neutral safety switch, wiring harness, battery, and a starter motor with an integral solenoid. These components form two separate circuits: a high amperage circuit that feeds the starter motor up to 300 or more amps, and a control circuit that operates on less than 20 amps.
Before commencing with the starting system diagnostics, verify:
Starter Feed Circuit
- Connect a volt-ampere tester (multimeter) to the battery terminals.
- Disable the ignition system.
- Verify that all lights and accessories are off, and the transmission shift selector is in Park (automatic) or Neutral (manual). Set the parking brake.
- Rotate and hold the ignition switch in the START position. Observe the volt-ampere tester:
- If the voltage reads above 9.6 volts, and the amperage draw reads above 250 amps, go to the starter feed circuit resistance test (following this test).
- If the voltage reads 12.4 volts or greater and the amperage reads 0-10 amps, refer to the starter solenoid and relay tests.
- After the starting system problems have been corrected, verify the battery state of charge and charge the battery if necessary. Disconnect all of the testing equipment and connect the ignition coil cable or ignition coil connector. Start the vehicle several times to assure the problem was corrected.
Before proceeding with this test, refer to the battery tests and starter feed circuit test. The following test will require a voltmeter, which is capable of accuracy to 0.1 volt.
- Disable the ignition system.
- With all wiring harnesses and components (except for the coils) properly connected, perform the following:
- Connect the negative ( - ) lead of the voltmeter to the negative battery post, and the positive ( + ) lead to the negative ( - ) battery cable clamp. Rotate and hold the ignition switch in the START position. Observe the voltmeter. If the voltage is detected, correct the poor contact between the cable clamp and post.
- Connect the positive ( + ) lead of the voltmeter to the positive battery post, and the negative ( - ) to the positive battery cable clamp. Rotate and hold the ignition switch key in the START position. Observe the voltmeter. If voltage is detected, correct the poor contact between the cable clamp and post.
- Connect the negative lead of the voltmeter to the negative battery terminal, and positive lead to the engine block near the battery cable attaching point. Rotate and hold the ignition switch in the START position. If the voltage reads above 0.2 volt, correct the poor contact at ground cable attaching point. If the voltage reading is still above 0.2 volt after correcting the poor contact, replace the negative ground cable with a new one.
- Refer to removal and installation procedures to gain access to the starter motor and solenoid connections. Perform the following steps:
- Connect the positive ( + ) voltmeter lead to the starter motor housing and the negative ( - ) lead to the negative battery terminal. Hold the ignition switch key in the START position. If the voltage reads above 0.2 volt, correct the poor starter to engine ground.
- Connect the positive ( + ) voltmeter lead to the positive battery terminal, and the negative lead to the battery cable terminal on the starter solenoid. Rotate and hold the ignition key in the START position. If the voltage reads above 0.2 volt, correct poor contact at the battery cable to the solenoid connection. If the reading is still above 0.2 volt after correcting the poor contacts, replace the positive battery cable with a new one.
- If the resistance tests did not detect feed circuit failures, refer to the starter solenoid test.
ON VEHICLE test
- Before testing, assure the parking brake is set, the transmission is in Park (automatic) or Neutral (manual), and the battery is fully charged and in good condition.
- Connect a voltmeter from the small terminal (terminal 50 ) on the solenoid to ground. Turn the ignition switch to the START position and test for battery voltage. If battery voltage is not found, inspect the ignition switch circuit. If battery voltage is found, proceed to next step.
- Connect an ohmmeter between the battery negative post and the starter housing. The ohmmeter should read zero (0). If not, repair the faulty ground.
- If both tests are performed and the solenoid still does not energize, replace the solenoid.
- Note the radio security code and the radio presets.
- Disconnect the battery negative cable then the positive cable.
- Remove the starter from the vehicle.
- Disconnect the field coil wire from the field coil terminal.
- Check for continuity between the solenoid terminal and field coil terminal with a continuity tester. Continuity (resistance) should be present.
- Check for continuity between the solenoid terminal and solenoid housing. Continuity should be detected. If continuity is detected, the solenoid is good.
- If continuity is not detected in either test, the solenoid has an open circuit, is defective, and must be replaced.
When performing these tests, it is important that the voltmeter be connected to the terminals, not the cables themselves.
Before testing, assure that the ignition control module (if equipped) is disconnected, the parking brake is set, the transmission is in Park (automatic) or Neutral (manual), and the battery is fully charged and in good condition.
- Check voltage between the positive battery post and the center of the B+ terminal on the starter solenoid stud.
- Check voltage between the negative battery post and the engine block.
- Disconnect the ignition coil wire from the distributor cap and connect a suitable jumper wire between the coil cable and a good body ground.
- Have an assistant crank the engine and measure voltage again. Voltage drop should not exceed 0.5 volts.
- If voltage drop is greater than 0.5 volts, clean metal surfaces. Apply a thick layer of silicone grease. Install a new cadmium plated bolt and star washer on the battery terminal and a new brass nut on the starter solenoid. Retest and replace cable not within specifications.
REMOVAL & INSTALLATION
- Note the radio security code, and then disconnect the battery ground cable.
- Raise and safely support the front of the vehicle with jackstands.
- If installed, remove the lower engine shield.
- If necessary, label the small wires before disconnecting them.
- On 1990-97 Passat models:
- To support the weight of the engine and transaxle, install the engine support Tool Nos. 10-222A and 10-222A/1, or use a floor jack (with a block of wood on the chock) to support the engine by the oil pan. Do NOT jack the car by the oil pan under any circumstances! The floor jack is ONLY to support the engine while the starter is being removed. This is necessary because the bolts that secure the starter to the transaxle are also used to secure the front engine mount to the transaxle.
- Disconnect the large cable, which is the positive battery cable, from the solenoid.
- If equipped, remove the bracket that secures the starter to the engine.
- On Audi A4 and 1998-00 Passat models:
- Release the number 50 electrical connector from the starter.
- Then remove the nut for the large battery cable and remove the cable.
- Loosen then remove the clamp that secures the heat shield to the starter.
- Remove the fasteners securing the bracket at the front of the starter and remove the bracket.
- Remove the starter mounting bolts, while supporting the weight of the starter.
- Pull the starter straight out from the transaxle.
- Install the starter into the transaxle.
- Tighten the related starter motor fasteners as follows:
- Starter support bracket, M5 nut: 35 inch lbs. (4 Nm)
- Starter support bracket, M8: 16 ft. lbs. (22Nm)
- Battery cable to solenoid, M8 nut:10 ft. lbs. (13Nm)
- hydraulic hose support bracket, M8: 84 inch lbs. (10Nm)
- Starter mounting fasteners, M10: 44 ft. lbs. (60 Nm)
- Starter mounting fasteners, M12: 48 ft. lbs. (65 Nm)
- The balance of the installation is in reverse order of removal.
- Lower the vehicle from the jackstands.
- Connect the negative battery cable and enter the radio security code.
Usually the starter and solenoid are replaced as an assembly. Finding a replacement solenoid is not as easy as finding a complete new or rebuilt starter. It's very possible the cost of the solenoid could be equal to the cost of a rebuilt starter motor. If the solenoid is worn, chances are that the starter motor has an equivalent amount of wear. Replacing both as an assembly reduces the chance of having problems with the starter motor soon after replacing the solenoid.
To replace the solenoid:
- Remove the starter motor.
- Disconnect the copper braid lead from the solenoid terminal. Be careful not to twist and pull on the lead as the nut is removed.
- Remove the 2 or 3 screws at the nose end of the solenoid. A hand impact and Phillips bit may be necessary.
- Remove the solenoid. Use care to not lose the spring in the solenoid.
- Install the solenoid onto the body of the starter. Coat the threads of the screws with a suitable thread-locking compound and tighten.
- Connect the copper braid lead to the solenoid terminal. Be careful not to twist or pull on the lead as the nut is tightened.
- Install the solenoid and reinstall the starter motor assembly.