Verify Ecm Powers Up; Circuit Description; Check Ecm Power And Grounds (Non-Scan Diagnostics) - Briggs & Stratton VANGUARD M490000 Repair Manual

Circuit Description

Since all EFI components are dependent on proper
operation of the ECM, any diagnosis must include
checking ECM power and grounds.

Check ECM Power and Grounds (Non-Scan Diagnostics)

Step
1 1. Turn Ignition OFF.
2. Back probe terminal J2-18 (Red wire) of ECM J2 (Black)
connector.
3. Connect terminal J2-18 back probe to red meter test lead on
DVOM.
4. Connect black meter test lead on DVOM to a known good
ground.
5. Set DVOM to read volts DC.
6. Turn Ignition ON, Engine OFF.
7. Observe voltage on DVOM.
8. Is reading 12.2-14.5 volts DC?
2 1. Turn Ignition OFF.
2. Remove probe from terminal J2-18, and back probe terminal
J2-15 (Red wire) of ECM J2 connector.
3. Connect terminal J2-15 back probe to red meter test lead on
DVOM.
4. Connect black meter test lead on DVOM to a known good
ground.
5. Turn Ignition ON, Engine OFF.
6. Observe voltage on DVOM.
7. Is reading 12.2-14.5 volts DC?
3 1. Turn Ignition OFF.
2. Remove probe from terminal J2-15, and back probe terminal
J2-02 (Black wire) of ECM J2 connector.
3. Connect terminal J2-02 back probe to red meter test lead on
DVOM.
4. Connect black meter test lead on DVOM to a known good
ground.
5. Set DVOM to read resistance.
6. Observe reading on DVOM.
7. Is resistance 1.0 ohm or less?

VERIFY ECM POWERS UP

Action
Remove and clean battery terminals. While terminals may
appear clean, corrosion on the inner surfaces can cause
a poor connection to ground.
NOTE: When the ECM is powered up, you may hear
the fuel pump module prime for two seconds. This is not
definitive proof that the ECM is getting proper voltage.
Yes
Go to step 2.
Go to step 3.
Go to step 4.
2
No
Look for open or short
to ground in battery
(B+) feed circuit.
Perform visual and
continuity check of
15 amp Ignition fuse
(Blue).
Look for open or
short to ground in
ignition feed circuit.
Look for open or short
in ECM ground circuit.
Continued...
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