Kohler COMMAND CH18-745 User Manual download pdf (Page 72)

5B.13

Section 5B

EFI Fuel System

a. If there is no continuity displayed in either of

the tests, check the harness circuit for breaks

or damage, and the connections for poor

contact, moisture, or corrosion. If no continuity

was found in the first test, also check for a

poor/broken ground path back through the

exhaust system, engine, and mounting

(sensor is grounded through its shell).

b. If continuity is indicated, go to step 6.

6. With the key switch in the ‘‘on/run’’ position, using

a high impedance voltmeter, check the voltage

from the wiring harness oxygen sensor connector

to the engine ground location. Look for a steady

voltage from 350-550 mv (0.35-0.55 v).

a. If voltage reading is not as specified, move the

black voltmeter lead to the negative post of the

battery, to be certain of a good ground. If the

voltage is still not correct, the ECU is probably

bad.

b. If voltage readings are correct, clear the fault

codes and run the engine to check if any fault

codes reappear.

To Replace Oxygen Sensor

1. Disconnect the oxygen sensor connector from

wiring harness.

2. Loosen and remove the oxygen sensor from the

exhaust manifold/muffler assembly.

3. Apply anti-seize compound sparingly to threads of

new oxygen sensor, if none already exists. DO

NOT get any on the tip as it will contaminate the

sensor. Install sensor and torque to 50-60 N·m

(37-44 ft. lb.).

4. Reconnect the lead to wiring harness connector.

Make sure it can not contact hot surfaces, moving

parts, etc.

5. Test run the engine.

Electrical Relay

Figure 5B-13. Electrical Relay.

General

The electrical relay is used to supply power to the

injectors, coils, and fuel pump. When the key switch is

turned “on” and all safety switch requirements met, the

relay provides 12 volts to the fuel pump circuit,

injectors, and ignition coils. The fuel pump circuit is

continuously grounded, so the pump is immediately

activated and pressurizes the system. Activation of the

ignition coils and injectors is controlled by the ECU,

which grounds their respective circuits at the proper

times.

Service

A malfunctioning relay can result in starting or

operating difficulties. The relay and related wiring can

be tested as follows.

1. Disconnect the relay connector plug from the

relay.

2. Connect black lead of VOA meter to a chassis

ground location. Connect red lead to the #86

terminal in relay connector (see Figure 5B-14).

Set meter to test resistance (Rx1). Turn ignition

switch from “off” to “on”. Meter should indicate

continuity (ground circuit is completed) for 1 to 3

seconds. Turn key switch back off.

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Kohler COMMAND CH18-745 User Manual Page 72

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