Mercury BRAVO Service Manual page 574

CORROSION PROTECTION - ALL MODELS
Low Readings (continued)
Faulty MerCathode reference electrode.
Faulty MerCathode Controller.
Additional corrosion protection required.
Boats equipped with a sizable amount of
underwater metal (stainless steel prop,
after planes, etc.), or that are moored in
an area with warm or rapid flowing water
may require additional protection.
Page 7A-20
Cause
SERVICE MANUAL NUMBER 28
Special Instructions
Disconnect the reference electrode
lead(brown) from the controller "R"
terminal. Connect the lead to the positive
(+) terminal of a digital multimeter (set on
0-2000 millivolt scale). Connect the
negative (–) meter lead to the negative (–)
battery terminal. Note the meter reading;
then repeat the test using a MerCathode
Reference Electrode Tester 76675A1. You
should obtain the same reading in both
cases. If not, replace the reference
electrode.
With anode and reference electrode leads
connected to the controller, connect the
jumper wire between "R" and negative (-)
terminals on the controller. Connect the
positive (+) lead of the volt meter (set on
0-20 scale) to terminal "A" on the
controller. Connect the negative (-) meter
lead to the negative (-) controller terminal.
Reading should be as follows:
D Freshwater Areas -
Electrodes Mounted on boat transom: 7.5
- 10.5 Millivolts
Electrode mounted on bottom transom
assembly: 6.2 - 11.8 Millivolts
D Saltwater Areas -
Electrodes mounted on boat transom: 8.8
- 10.5 Millivolts
Electrode mounted on bottom of transom
assembly: 7.5 - 11.8 Millivolts
If the reading is low, replace the controller.
Install additional anodes or MerCathode
system 88334A2. If the unit is already
equipped with a MerCathode system, a
second system may be required.
90-863160 MAY 2000