0398365 JOHNSON CARB. ASSY., Lower, 225

Table 1
J1939 Code and Description CDL Code and Description Comments
7598-5
Aftertreatment #1 DEF Backflow Valve #1 : Current Below Normal 5024-5
Aftertreatment #1 DEF Backflow Valve #1 : Current Below Normal This code indicates that there is a problem with the aftertreatment #1 DEF backflow valve #1 and/or the electrical circuit for the backflow valve.
7598-6
Aftertreatment #1 DEF Backflow Valve #1 : Current Above Normal 5024-6
Aftertreatment #1 DEF Backflow Valve #1 : Current Above Normal This code indicates that there is a problem with the aftertreatment #1 DEF backflow valve #1 and/or the electrical circuit for the backflow valve.
7599-5
Aftertreatment #1 DEF Backflow Valve #2 : Current Below Normal 5025-5
Aftertreatment #1 DEF Backflow Valve #2 : Current Below Normal This code indicates that there is a problem with the aftertreatment #1 DEF backflow valve #2 and/or the electrical circuit for the backflow valve.
7599-6
Aftertreatment #1 DEF Backflow Valve #2 : Current Above Normal 5025-6
Aftertreatment #1 DEF Backflow Valve #2 : Current Above Normal This code indicates that there is a problem with the aftertreatment #1 DEF backflow valve #2 and/or the electrical circuit for the backflow valve.
7600-5
Aftertreatment #2 DEF Backflow Valve #1 : Current Below Normal 5026-5
Aftertreatment #2 DEF Backflow Valve #1 : Current Below Normal This code indicates that there is a problem with the aftertreatment #2 DEF backflow valve #1 and/or the electrical circuit for the backflow valve.
7600-6
Aftertreatment #2 DEF Backflow Valve #1 : Current Above Normal 5026-6
Aftertreatment #2 DEF Backflow Valve #1 : Current Above Normal This code indicates that there is a problem with the aftertreatment #2 DEF backflow valve #1 and/or the electrical circuit for the backflow valve.
7601-5
Aftertreatment #2 DEF Backflow Valve #2 : Current Below Normal 5027-5
Aftertreatment #2 DEF Backflow Valve #2 : Current Below Normal This code indicates that there is a problem with the aftertreatment #2 DEF backflow valve #2 and/or the electrical circuit for the backflow valve.
7601-6
Aftertreatment #2 DEF Backflow Valve #2 : Current Above Normal 5027-6
Aftertreatment #2 DEF Backflow Valve #2 : Current Above Normal This code indicates that there is a problem with the aftertreatment #2 DEF backflow valve #2 and/or the electrical circuit for the backflow valve.
Table 2
Required Tools
Part Number Part Name Qty
372-5260 Test Lead Tool Group 1
Illustration 1 g06522459
(1) Coolant diverter valve for Aftertreatment #1 DEF pump #1 system (blue)
(2) Coolant diverter valve for Aftertreatment #1 DEF pump #2 system (green)
(3) Aftertreatment #1 DEF pump #1 header (blue)
(4) Aftertreatment #1 DEF pump #2 header (green)
(5) Aftertreatment #2 DEF pump #1 header (yellow)
(6) Aftertreatment #2 DEF pump #2 header (red)
(7) Coolant diverter valve for Aftertreatment #2 DEF pump #1 system (yellow)
(8) Coolant diverter valve for Aftertreatment #2 DEF pump #2 system (red)
(9) Aftertreatment #2 DEF pump #2 (red)
(10) DEF backflow valve for Aftertreatment #2 DEF pump #2 system (red)
(11) Aftertreatment #2 DEF pump #1 (yellow)
(12) DEF backflow valve for Aftertreatment #2 DEF pump #1 system (yellow)
(13) Aftertreatment #1 DEF pump #2 (green)
(14) DEF backflow valve for Aftertreatment #1 DEF pump #2 system (green)
(15) Aftertreatment #1 DEF pump #1 (blue)
(16) DEF backflow valve for Aftertreatment #1 DEF pump #1 system (blue)
Illustration 2 g06552830
The DEF injectors are on the inlet of the Clean Emissions Module (CEM). There are injectors on both inlets of the dual CEM applications.
(17) Aftertreatment #1 DEF pump #2 DEF injector #1 (green)
(18) Aftertreatment #1 DEF pump #1 DEF injector #2 (blue)
(19) Aftertreatment #1 DEF pump #1 DEF injector #3 (blue)
(20) Aftertreatment #1 DEF pump #2 DEF injector #4 (green)
(21) Aftertreatment #2 DEF pump #2 DEF injector #1 (red)
(22) Aftertreatment #2 DEF pump #1 DEF injector #2 (yellow)
(23) Aftertreatment #2 DEF pump #1 DEF injector #3 (yellow)
(24) Aftertreatment #2 DEF pump #2 DEF injector #4 (red)
Table 3
Troubleshooting Test Steps Values Results
1. Check for Codes
A. Connect Cat® Electronic Technician (ET) to the service tool connector.
B. Determine if a code is active or logged.
Codes
Result: A -5 code is active or logged.
Proceed to Test Step 2.
Result: A -6 code is active or logged.
Proceed to Test Step 3.
2. Check the Backflow Valve Wiring Harness for an Open 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 Diesel Exhaust Fluid Controllers (DCU’s).
B. Disconnect the Pump Electronic Tank Unit (PETU) wiring harness from the affected DEF backflow valve and the affected DCU.
C. Connect the 398-5063 Probe to the DCU connector.
The probe must be used to prevent damage to the DCU connector.
D. Measure the resistance between the following terminals on the affected DEF backflow valve wiring harness connector and the affected 86-pin DCU wiring harness connector:
- For Aftertreatment #1 DCU #1, Terminal 1 (Supply) on the affected DEF backflow valve wiring harness connector and Terminal 11 (DEF Backflow Valve (+)) on the 86-pin DCU connector.
- For Aftertreatment #1 DCU #1, Terminal 2 (Return) on the affected DEF backflow valve wiring harness connector and Terminal 31 (DEF Backflow Valve (-)) on the 86-pin DCU connector.
- For Aftertreatment #1 DCU #2, Terminal 1 (Supply) on the affected DEF backflow valve wiring harness connector and Terminal 11 (DEF Backflow Valve (+)) on the 86-pin DCU connector.
- For Aftertreatment #1 DCU #2, Terminal 2 (Return) on the affected DEF backflow valve wiring harness connector and Terminal 31 (DEF Backflow Valve (-)) on the 86-pin DCU connector.
- For Aftertreatment #2 DCU #1, Terminal 1 (Supply) on the affected DEF backflow valve wiring harness connector and Terminal 11 (DEF Backflow Valve (+)) on the 86-pin DCU connector.
- For Aftertreatment #2 DCU #1, Terminal 2 (Return) on the affected DEF backflow valve wiring harness connector and Terminal 31 (DEF Backflow Valve (-)) on the 86-pin DCU connector.
- For Aftertreatment #2 DCU #2, Terminal 1 (Supply) on the affected DEF backflow valve wiring harness connector and Terminal 11 (DEF Backflow Valve (+)) on the 86-pin DCU connector.
- For Aftertreatment #2 DCU #2, Terminal 2 (Return) on the affected DEF backflow valve wiring harness connector and Terminal 31 (DEF Backflow Valve (-)) on the 86-pin DCU connector.
Open Circuit
Result: There were less than 10 Ohms of resistance