811669A 1 Mercury CYLINDER

Contact with high pressure fuel may cause fluid penetration and burn hazards. High pressure fuel spray may cause a fire hazard. Failure to follow these inspection, maintenance and service instructions may cause personal injury or death.
This procedure covers the following diagnostic trouble codes.
Table 1
Code Description Conditions Notes
651-3 Open circuit of harness/coil in first cylinder injector Engine is running.
Battery voltage is normal.
Occurs during injection
CPU is normal Open circuit occurs eight times or more.
Engine derates
EGR stops.
Intake throttle is open 100 percent
Warning Level 3
Other injectors continue to operate, which will cause increase vibration.
652-3 Open circuit of harness/coil in second cylinder injector
653-3 Open circuit of harness/coil in third cylinder injector
654-3 Open circuit of harness/coil in fourth cylinder injector
651–6 Coil Short in first Injector (only applies to C3.8 Tier 4 Final / Stage IV) Battery voltage is normal.
During injection.
CPU is normal. Injector coil short (over current) 8 times or more.
Injector with error stops injection.
Engine derates 25%.
EGR Stop.
652-6 Coil Short in third Injector (only applies to C3.8 Tier 4 Final / Stage IV)
653-6 Coil Short in fourth Injector (only applies to C3.8 Tier 4 Final / Stage IV)
654-6 Coil Short in second Injector (only applies to C3.8 Tier 4 Final / Stage IV)
3361-5 DEF Injector Short to Ground or Open Circuit or Short to +B (ground short or open circuit of harness or DEF Injector Coil) Battery voltage is normal
Key switch signal (ECM: V13 & V33, DCU: 18 terminal) is continuously activated more than 2 sec
Starter Switch signal (ECM: V12 terminal) is not activated except within 2 sec after starter stopped
CAN communication is normal between DCU and engine ECM
PWM duty cycle is more than 6% When the DEF injector is operating, the injector electrical current monitoring voltage is 0.200 V or less, or 1.1 V or more for 40 ms (4 ms sampling) or more for 3 times.
Stop DEF Injection
523523-2 Common 1 System Injector Drive Circuit Open
Engine is running
Battery voltage is normal
Occurs during injection
CPU is normal
Engine derated
EGR stop
Intake throttle is open 100%
Warning Level 3
523524-2 Common 2 System Injector Drive Circuit Open
523523-3 Common 1 TWV Actuation System Ground Short
Engine is operating
Battery voltage is normal
Injectors that have DTC will stop injection
Engine is derated
EGR stop
Intake throttle is 100% open
Warning Level 3
523523-4 Common 1 TWV Actuation System +B Short
523524-3 Common 2 TWV Actuation System Ground Short
523524-4 Common 2 TWV Actuation System +B Short
523525-1 Injector charge voltage: Low
Battery Voltage is normal
Injector charge voltage is Low
Engine derated
EGR stop
Intake throttle 100% open
523535-0 Injector Charge Voltage: High
Battery voltage is normal
Injector charge voltage: High for more than 10 seconds
Engine derated
EGR stop
Intake throttle 100% open
For the 3361-5 DEF Injector Short to Ground or Open Circuit or Short to +B (ground short or open circuit of harness or DEF Injector Coil), use Table 2.For the Coil Short in Injector codes (651-6, 652-6, 653-6, 654-6) use Table 4.For the 523535-0 Injector Charge Voltage High, use Table 5.For all other codes, refer to Table 6.For the 523525-1 Injector Charge Voltage Low, turn off engine clear the DTC code and restart engine.
Illustration 1 g06204051
(1) Terminal INJ (+)
(2) Terminal INJ (-)
(a) Terminal Layout
(b) DEF Injector
(c) DCU Connector
Table 2
Troubleshooting Steps for 3361-5
Troubleshooting Test Steps Values Results
1. Measure the Resistance Between the DEF Injector Terminals
A. Check the DEF injector wiring harness for damage or poor contact with the connector.
B. Unplug the DEF injector connector, and measure the resistance between injector terminals pin 1 and 2.
DEF Injector
Result: The resistance is not 7Ω.
Repair: Replace the DEF injector.
If the problem is not resolved, proceed to Test Step 2.
Result: The resistance is 7Ω.
Repair: Replace the DEF injector wiring harness.
If the problem is not resolved, proceed to Test Step 2.
2. Measure the Resistance of the DCU Harness
A. Turn the keyswitch to OFF.
B. Unplug the DCU wiring harness connector from the DCU socket.
B. Measure the resistance between terminals pin 40, 41, 46, 47, 48 or 49 of the connector and the chassis ground.
DCU Harness
Result: The resistance is 1.5 Ω or lower.
Proceed to Test Step 3.
Result: The resistance is not 1.5 Ω or lower.
Repair: Inspect/replace the DCU wiring harness.
3. Measure the Resistance Between Pin 7 and 8 of the DCU Wiring Harness Connector
7 Ω
Result: The resistance is 7Ω.
Proceed to Test Step 4.
Result: The resistance is not 7Ω.
Repair: Inspect the DCU connector and wiring for damage. Repair or replace the connector as needed.
4. Check the DCU for Damage