Connector Pin Wire Color Function PCM
A Black Chassis ground (–) –
B Purple 12 V wake circuit (+) CC1
C White/blue Power steering AG4
Troubleshooting an Inoperable Power Steering Pump
1. Verify that battery cables, power steering pump signal harnessing, and driver module are installed according to the
engine’s installation/service manual architecture.
2. Verify that battery voltage is present on the battery cables leading to the power steering pump (be sure to check the
voltage on the power steering pump side of the fuse located on the positive cable).
a. When battery voltage is present on these leads, indicating a good fuse, the power steering pump will actuate when
the expected voltage is completed from the power steering signal harness/driver module. This voltage is sent in a
two‑step process: Step 1 ‑ key on, then Step 2 ‑ engine starts and runs.
• The power steering pump may ramp‑up slowly if this two‑step process is not performed as instructed.
• The power steering pump will not actuate unless the engine is running.
3. Check for proper voltage across the power steering driver module. To test, break the connection point between the driver
module and the power steering pump wiring.
a - Power steering pump harness connector
b - Power steering driver module
c - Pin 1 (blue/white)
d - Pin 2 (purple)
a. With the key in the off position, no voltage should be present across the blue/white to purple wire or across either of
these wires to ground.
b. With the key on and the engine off, battery voltage must be present across the purple lead and the engine/battery
ground.
• There should be less than 1 volt (< 1 volt) across the blue/white wire and battery ground.
DMT Meter Leads
Red Black Circuit voltage =
Power steering driver module ‑
key on and engine off
Purple Engine/battery ground Battery voltage
Blue/white Engine/battery ground < 1 volt
c. With the engine running, battery voltage should be present across the blue/white lead and engine/battery ground and
across the purple lead to the engine/battery ground.
DMT Meter Leads
Red Black Circuit voltage =
Power steering driver module ‑
engine starts and runs
Purple Engine/battery ground Battery voltage
Blue/white Engine/battery ground Battery voltage
Accessories
90-8M0146617 eng JULY 2018 © 2018 Mercury Marine Page 5C-5
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