Diagnostics (Rs48); Battery Isolator Troubleshooting - Mercury V6 175 Diagnostic Manual

Diagnostics (RS48)

This connector is labeled as "Diagnostics RS48," however Mercury's CDS G3 diagnostic tool always connects to the 10‑pin
SmartCraft connection. This connector is used instead for the connection of a depth transducer. The PCM communicates with
the transducer and then broadcasts the information onto the SmartCraft network for display at the helm. CDS G3 will also
display the depth data under the Vessel tab of the Live Data display for troubleshooting purposes.
H
f
A
4 1
a - Hot stud (battery +)
b - Main power relay (MPR)
c - Fuse block: 2‑amp fuse
d - Chassis ground (–)
e - Diagnostic (RS48) connector
f - PCM connector A
Connector
A B
Hot stud ring terminal
MPR
MPR

Battery Isolator Troubleshooting

Battery isolators allow a single alternator to charge two batteries, while ensuring that the engine essential loads are isolated to
the engine starting battery. Vessel or "house" loads are isolated to the house battery. This makes certain that the engine
starting battery will have a sufficient charge to start the engine even if the house battery was depleted. Battery isolators also
ensure that the starting battery receives a charge from the alternator while the engine is running, and excess available charge
from the alternator is directed to the house battery. If the engine alternator is functioning correctly but one or both batteries fail
to receive a charge, then perform the following test of the battery isolator.
Engine Off Test
1. Turn off the battery charger.
Disable any parallel switches or
2.
VSR's.
3. Turn on the engine battery switch. 3. Turn on the engine battery switch.
4. Turn on the house battery switch. 4. Turn on the house battery switch.
90-8M0146617 eng JULY 2018
b
87
85
a
30
30858687
109B
A1
A2
BLU/WHT
E3
WHT/BLU
E4
H4
Pin Wire Color
A Black
D
C
B Blue/white
C White/blue
61348
D Red/orange
–
86 Yellow/purple
87 Red/white
Engine Key On Test
1. Turn off the battery charger.
Disable any parallel switches or
2.
VSR's.
A1 A2 A3 A4 A5 A6
c
B1 B2 B3 B4 B5 B6
C1 C2 C3 C4 C5
86
2A
A1 B1 B2
105B
105C
Fused (2 A) 12 V power (+)
Red
Main power relay (MPR) control signal
© 2018 Mercury Marine
C6
C6
104B
BLK
RED/ORN D
WHT/BLU
C
BLU/WHT B
A
Function
Chassis ground (–)
Serial communications +
Serial communications –
12 V battery power (+)
Switched 12 V power (+)
Engine Running Test
1. Turn off the battery charger.
2. Disable any parallel switches or VSR's.
3. Turn on the engine battery switch.
4. Turn on the house battery switch.
Accessories
d
e
65449
PCM
–
AE3
AE4
–
–
AA2
–
Page 5C-9