3034 Engine for Caterpillar Built Machines Caterpillar

Illustration 1	g00395324
Glow plugs and connectors (1) Terminal of the glow plug (2) Connector

Test the Continuity of the Glow Plug Circuit

1. Connect the 8T-0500 Test Light between ground and the terminal of glow plug (1). Choose the terminal of glow plug (1) that is farthest from the battery. Turn the starting aid switch to the ON position.

   The test light should turn on if the circuits are correct for the power supply.

   If the test light does not turn on, inspect the circuits for the power supply for loose connections, broken wires, and other damage.

2. Disconnect connectors (2) from each glow plug.

3. Connect the test light to the positive terminal of the battery and to terminal (1) of a glow plug. If the light turns on, there is a continuous electrical path to the glow plugs.

   If the light does not turn on, replace the glow plug.

   Repeat this step for each glow plug.

Test the Operation of the Glow Plugs

1. Disconnect the cable for the power supply to connectors (2). Disconnect the connectors from terminals (1) of the glow plugs.

2. Connect the 6V-7070 Digital Multimeter between the cable for the power supply and the terminal of a glow plug. Turn on the starting aid switch. Observe the amperage reading of the multimeter. Then, connect the leads of the multimeter between the terminal of the glow plug and a ground. Measure the voltage.

   The initial current to a glow plug should be approximately 12.5 amperes. The current should decrease to 7 ± 1 amperes after 30 seconds.

   The voltage should be 12 ± 0.5 volts.

   Perform this step for each glow plug.

3. If the initial current to a glow plug is below 12.5 amperes and the current decreases to a value that is below 7 ± 1 amperes, replace the glow plug. If there is no reading, replace the glow plug.

   If the voltage reading of the multimeter is zero, inspect the starting aid switch and the power supply for faulty components and loose connections.

4. When the tests are complete, connect the connectors to the terminals of the glow plugs. Connect the cable for the power supply to the glow plugs.

Note: Earlier engines were supplied with 177-7559 Glow Plugs. Later engines are shipped with 153-0525 Glow Plugs. The initial current to 153-0525 Glow Plugs is 12.5 amperes. The initial current to 177-7559 Glow Plugs is 25 amperes. If 153-0525 Glow Plugs are replaced by 177-7559 Glow Plugs, electrical connectors of correct current carrying capacity must be used. Please refer to Table 2.

Illustration 2	g00712246
(1) Glow plugs (2) Glow plug wires (3) Electrical cable from glow plug relay to glow plug (4) Glow plug relay (5) Electrical cable from starter motor solenoid to glow plug relay (6) Starter motor solenoid

Note: If the 177-7559 Glow Plug replaces 153-0525 Glow Plug, the electrical connector (3) between the glow plug relay and the fourth glow plug must be replaced. If the 177-7559 Glow Plug replaces 153-0525 Glow Plug, the electrical connector (5) between the starter motor solenoid and the glow plug relay must also be replaced. Please refer to Illustration 2.