56171 Mercruiser COVER, ROCKER (STARBOARD)

Table 1
J1939 Code and Description CDL Code and Description Comments
5966-5
Aftertreatment #1 DEF Control Module Power Supply : Current Below Normal 3965-5
Aftertreatment #1 Diesel Exhaust Fluid Control Module Power Supply #1 : Current Below Normal An open circuit has been detected on the keyswitch circuit between the Selective Catalyst Reduction (SCR) System and the Diesel Exhaust Fluid Control Unit (DCU).
5966-6
Aftertreatment #1 DEF Control Module Power Supply : Current Above Normal 3965-6
Aftertreatment #1 Diesel Exhaust Fluid Control Module Power Supply #1 : Current Above Normal A short circuit has been detected on the keyswitch circuit between the SCR System and the DCU.
5968-5
Aftertreatment #2 DEF Control Module Power Supply : Current Below Normal 4801-5
Aftertreatment #2 DEF Controller #1 Power Supply #1 : Current Below Normal An open circuit has been detected on the keyswitch circuit between the Selective Catalyst Reduction (SCR) System and the Diesel Exhaust Fluid Control Unit (DCU).
5968-6
Aftertreatment #2 DEF Control Module Power Supply : Current Above Normal 4801-6
Aftertreatment #2 DEF Controller #1 Power Supply #1 : Current Above Normal A short circuit has been detected on the keyswitch circuit between the SCR System and the DCU.
6309-5
Aftertreatment #1 DEF Control Module #1 Power Supply #2 : Current Below Normal 3966-5
Aftertreatment #1 Diesel Exhaust Fluid Control Module Power Supply #2 : Current Below Normal An open circuit has been detected on the keyswitch circuit between the SCR System and the DCU.
6309-6
Aftertreatment #1 DEF Control Module #1 Power Supply #2 : Current Above Normal 3966-6
Aftertreatment #1 Diesel Exhaust Fluid Control Module Power Supply #2 : Current Above Normal A short circuit has been detected on the keyswitch circuit between the SCR and the DCU.
6310-5
Aftertreatment 2 Diesel Exhaust Fluid Control Module 1 Power Supply 2 : Current Below Normal 4802-5
Aftertreatment #2 DEF Controller #1 Power Supply #2 : Current Below Normal An open circuit has been detected on the keyswitch circuit between the SCR System and the DCU.
6310-6
Aftertreatment 2 Diesel Exhaust Fluid Control Module 1 Power Supply 2 : Current Above Normal 4805-6
Aftertreatment #2 DEF Controller #1 Power Supply #2 : Current Above Normal A short circuit has been detected on the keyswitch circuit between the SCR and the DCU.
7522-5
Aftertreatment #1 DEF Control Module #2 Power Supply #1 : Current Below Normal 4799-5
Aftertreatment #1 Diesel Exhaust Fluid Controller #2 Power Supply #1 : Current Below Normal An open circuit has been detected on the keyswitch circuit between the SCR System and the DCU.
7522-6
Aftertreatment #1 DEF Control Module #2 Power Supply #1 : Current Above Normal 4799-6
Aftertreatment #1 Diesel Exhaust Fluid Controller #2 Power Supply #1 : Current Above Normal A short circuit has been detected on the keyswitch circuit between the SCR System and the DCU.
7523-5
Aftertreatment #1 DEF Control Module #2 Power Supply #2 : Current Below Normal 4800-5
Aftertreatment #1 Diesel Exhaust Fluid Controller #2 Power Supply #2 : Current Above Normal An open circuit has been detected on the keyswitch circuit between the SCR System and the DCU.
7523-6
Aftertreatment #1 DEF Control Module #2 Power Supply #2 : Current Above Normal 4800-6
Aftertreatment #1 Diesel Exhaust Fluid Controller #2 Power Supply #2 : Current Above Normal A short circuit has been detected on the keyswitch circuit between the SCR System and the DCU.
7533-5
Aftertreatment 2 Diesel Exhaust Fluid Control Module 2 Power Supply 1 : Current Below Normal 4803-5
Aftertreatment #2 DEF Controller #2 Power Supply #1 : Current Below Normal An open circuit has been detected on the keyswitch circuit between the SCR System and the DCU.
7533-6
Aftertreatment 2 Diesel Exhaust Fluid Control Module 2 Power Supply 1 : Current Above Normal 4803-6
Aftertreatment #2 DEF Controller #2 Power Supply #1 : Current Above Normal A short circuit has been detected on the keyswitch circuit between the SCR System and the DCU.
7534-5
Aftertreatment 2 Diesel Exhaust Fluid Control Module 2 Power Supply 2 : Current Below Normal 4804-5
Aftertreatment #2 DEF Controller #2 Power Supply #2 : Current Below Normal An open circuit has been detected on the keyswitch circuit between the SCR System and the DCU.
7534-6
Aftertreatment 2 Diesel Exhaust Fluid Control Module 2 Power Supply 2 : Current Above Normal 4804-6
Aftertreatment #2 DEF Controller #2 Power Supply #2 : Current Above Normal A short circuit has been detected on the keyswitch circuit between the SCR System and the DCU.
Illustration 1 g06300380
The DCUs are on the sides of the Pump Electronic Tank Unit (PETU).
(1) Aftertreatment #2 .DCU #1 (yellow)
(2) Aftertreatment #2 .DCU #2 (red)
(3) Aftertreatment #1 .DCU #2 (green)
(4) Aftertreatment #1 DCU #1 (blue)
Table 2
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 Diesel Exhaust Fluid Control Unit (DCU) Wiring for an Open Circuit
A. Turn the keyswitch to the OFF position for 2 minutes. The keyswitch must be off for 2 minutes to allow the DEF pump to purge, to reset the code, and to reset the DCU.
B. Disconnect the 70-pin J1 and 70-pin J2 connector from the SCR Electronic Control Module (ECM).
C. Disconnect the 53-pin connector from the affected DCU.
D. Connect the 398-5063 Probe to the DCU connector.
The probe must be used to prevent damage to the DCU connector.
E. Measure the resistance between the following pins on the affected DCU wiring harness connector:
- For Aftertreatment #1 DCU #1 measure between pin 10 on the 70-pin SCR System ECM J1 connector and pin 52 on