Refer to the Caterpillar 3126B HEUI (Hydraulically Actuated Electronic Unit Injectors) Diesel Truck  Engine Service Manual (Cat® Form No. RENR1360), Electronic Troubleshooting Section (Cat® Form No. RENR1367), for additional information about the operation of the engine exhaust (EE) brake system.

System voltage and controls ground are provided by the powertrain control module (PCM). The PCM monitors all the necessary inputs and outputs for the engine exhaust (EE) brake system operation.

When all conditions are met, the PCM provides a 12 volt output at terminal 12 that supplies power through circuit 1961 (WHT) to the EE brake switch. If the EE brake switch is selected (closed), the switch supplies that power to the EE brake/ air interlock relay through circuit 1164 (PPL) and splice S250 to terminals 30 and 85. The electronic brake control module (EBCM) provides a ground through circuit  1905 (PNK) at terminal K1, connector C2 , for the control-side of the EE brake/ air interlock relay at terminal 86. When the EE brake switch is selected (closed), voltage is applied from the normally-closed contacts of the EE brake/ air interlock relay at terminal 87A to splice S252. From splice S252, circuit 1962 (BLK/WHT) then powers the EE brake switch indicator and the EE brake solenoid valve. The EE brake solenoid valve and the EE brake switch indicator are grounded by circuit 150 (BLK) at ground G101. The EE brake solenoid valve and the EE brake switch indicator will remain energized as long as power is received from the PCM, the switch is selected, and ground is provided by both the EBCM and ground G101.

Refer to the Caterpillar 3126B HEUI (Hydraulically Actuated Electronic Unit Injectors) Diesel Truck  Engine Service Manual (Cat® Form No. RENR1360), Electronic Troubleshooting Section (Cat® Form No. RENR1367), for additional information about the operation of the engine exhaust (EE) brake system.

System voltage is provided by the powertrain control module (PCM). Ground is provided by G101. The PCM monitors all the necessary inputs and outputs for the engine exhaust (EE) brake system operation.

When all conditions are met, the PCM provides a 12 volt output at terminal 12 that supplies power through circuit 1961 (WHT) to the EE brake switch. If the EE brake switch is selected (closed), the switch supplies that power through circuit 1962 (BLK/WHT) to splice S252. From splice S252 circuit 1962 (BLK/WHT) then powers the EE brake switch indicator and the EE brake solenoid valve. The EE brake solenoid valve and the EE brake switch indicator are grounded by circuit 150 (BLK) at ground G101. The EE brake solenoid valve and the EE brake switch indicator will remain energized as long as power is provided by the PCM, the EE brake switch is selected and ground is provided by ground G101.