HOSE ASSEM. 3N7237 - Caterpillar

Table 2
Required Tools
Part Number Part Name Qty
372-5260 Test Lead Tool Group 1
Illustration 1 g06071647
Illustration 2 g06022979
The Diesel Exhaust Fluid (DEF) pumps are on the front side of the Pump Electronic Tank Unit (PETU).
(1) DEF pump 1
(2) DEF pump 2
Illustration 3 g06032975
The Diesel Exhaust Fluid Control Units (DCUs) are on the rear of the PETU.
(3) DCU 2
(4) DCU 1
Table 3
Troubleshooting Test Steps Values Results
1. Check the Pump Electronic Tank Unit (PETU) Wiring Harness for the DEF Pump Motor for an Open Circuit
A. Turn the keyswitch to the "OFF" position. The keyswitch must be OFF for 2 minutes to allow the DEF pumps to purge, reset the code, and reset the Diesel Exhaust Fluid Control Units (DCU's).
B. Disconnect the PETU wiring harness from the affected DEF pump and the affected DCU.
C. Connect the 398-5063 Probe to the DCU wiring harness connector.
D. Connect the 398-5056 Probe to the pump wiring harness connector.
The probe must be used to prevent damage to the DCU and pump wiring harness connectors.
E. Measure the resistance between the following terminals of the affected DEF pump wiring harness connector and the affected 86-pin DCU wiring harness connector:
- Terminal 9 (PWM +) on the DEF pump wiring harness connector and Terminal 46 (PWM +) on the 86-pin DCU wiring harness connector.
- Terminal 8 (PWM -) on the DEF pump wiring harness connector and Terminal 26 (PWM -) on the 86-pin DCU wiring harness connector.
- Terminal 10 (PWM SIGNAL) on the DEF pump wiring harness connector and Terminal 24 (PWM SIGNAL) on the 86-pin DCU wiring harness connector.
Open Circuit
Result: There were less than 10 Ohms of resistance on all the DEF pump motor circuit wires.
Proceed to Test Step 2.
Result: There were more than 10 Ohms of resistance on any one of the DEF pump motor circuit wires.
Repair: There is an open in the wiring harness. Repair or replace the wiring harness.
Verify that the repair eliminated the problem.
Proceed to Test Step 4.
2. Check the PETU Wiring Harness for the DEF Pump Motor for a Short Circuit
A. Turn the keyswitch to the "OFF" position. The keyswitch must be OFF for 2 minutes to allow the DEF pump to purge, reset the code, and reset the DCU.
B. Disconnect the PETU wiring harness from the affected DEF pump and the affected DCU.
C. Connect the 398-5063 Probe to the DCU wiring harness connector.
D. Connect the 398-5056 Probe to the pump wiring harness connector.
The probe must be used to prevent damage to the DCU and pump wiring harness connectors.
E. Measure the resistance between the following terminals on the affected DEF pump wiring harness connector and a known good chassis ground:
- Terminal 9 (PWM +) on the DEF pump wiring harness connector and a known good chassis ground.
- Terminal 8 (PWM -) on the DEF pump wiring harness connector and a known good chassis ground.
- Terminal 10 (PWM SIGNAL) on the DEF pump wiring harness connector and a known good chassis ground.
Short Circuit
Result: There were more than 100K Ohms of resistance between the connector terminal