Schematic Reference: Engine Exhaust Brake Schematics

1

Did you review the Exaust Brake Description and Operation and perform the necessary inspections?

Go to Step 2

Go to Symptoms - Engine Exhaust Brake

1. Drain the auxiliary air tank.
2. Turn ON the ignition.

Does the auxiliary air compressor turn ON?

Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

1. Disconnect the auxiliary air tank pressure switch connector.
2. Use a fused jumper wire to connect the two leads of the auxiliary air tank pressure switch connector.
3. Turn ON the ignition.

Does the auxiliary air compressor turn ON?

Go to Step 4

Go to Step 6

Test for an intermittent or poor connection at the auxiliary air tank pressure switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 15

Go to Step 5

Replace the auxiliary air tank pressure switch.

Did you complete the repair?

Go to Step 15

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Test for an intermittent or poor connection at the auxiliary air compressor switch and relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 15

Go to Step 7

Test for an open or short to ground in the ignition 3 circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 15

Go to Step 8

1. Reconnect the auxiliary air tank pressure switch.
2. Disconnect the auxiliary air compressor connector.
3. Connect a test lamp to a good ground and probe the battery positive voltage circuit. Refer to Probing Electrical Connectors in Wiring Systems.
4. Turn ON the ignition.

Does the test lamp turn ON?

Go to Step 9

Go to Step 10

Test for an intermittent or poor connection at the auxiliary air compressor connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 15

Go to Step 13

Test for an open or short to ground in the battery positive voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 15

Go to Step 11

Test for an open in the auxiliary air compressor relay ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 15

Go to Step 12

Replace the auxiliary air compressor relay.

Did you complete the replacement?

Go to Step 15

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Test for an open in the auxiliary air compressor ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 15

Go to Step 14

Replace the auxiliary air compressor.

Refer to Auxiliary Air Compressor Replacement .

Did you complete the replacement?

Go to Step 15

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1. Turn ON the ignition.
2. Wait up to 5 minutes.

Does the auxiliary air system pressurize then turn off?

System OK

Go to Step 2