Guardian Technologies 4270 manual TEST 18 - TRY CRANKING THE ENGINE, TEST 19- TEST PRE-HEAT SWITCH

Section 7

DIAGNOSTIC TESTS

*Resistance values in ohms at 20° C. (68° F.). Actual readings may vary depending on ambient temperature. A tolerance of plus or minus 5% is allowed.

RESULTS:

1.For Steps 2 & 3, keep in mind that the resistance values are very low. Depending upon the quality of the VOM, it may read “Continuity” across these windings. Exercise good judgement with these values.

2.If Steps 2, 3, 4, 5 & 6 fail any test, replace the Stator.

3.In Step 7, if Wire 0 reads “Continuity”, but resistor does not measure 1 ohm, replace the Battery Charge Resistor.

4.If all of the Steps in this test pass, perform “Insulation Resistance Test” on page 13.

TEST 18 - TRY CRANKING THE ENGINE

DISCUSSION:

If the Pre-Heat Switch on the generator panel is actu- ated, but the Fuel Pump does not run (priming func- tion doesn't work), perhaps battery voltage is not available.

PROCEDURE:

Hold the Start-Stop Switch at “START”. The engine should crank and start.

RESULTS:

1.If the engine cranks normally, but the pre-heat function still doesn't work, go to Test 19.

2.If engine will not crank, go to Test 21. Refer to Problem 6 of Section 6.

3.If engine cranks but won't start, go to Problem 7 of Section 6.

4.If engine starts hard and runs rough, go to Problem 8 of Section 6.

TEST 19- TEST PRE-HEAT SWITCH

DISCUSSION:

A defective pre-heat switch can prevent the pre-heat function from occurring.

(Also see “Pre-Heat Switch,” page 26).

NOTE: The glow plugs can be damaged by exces- sive use of the preheat switch. Press the preheat switch for 30 seconds or less to prevent such damage.

PROCEDURE:

1.Set a VOM to read battery voltage (12 VDC).

2.Connect the positive (+) meter test lead to the Wire 15 terminal of the Pre-Heat Switch (leave Wire 15 connected to the

switch). Connect the negative (-) meter test lead to ground. The meter should indicate battery voltage.

3.Connect the positive (+) meter test lead to the Wire 150 termi- nal of the Pre-Heat Switch, the negative (-) meter test lead to frame ground.

a.With the Pre-Heat Switch NOT actuated, no voltage should be indicated.

b.Actuate the switch to its “PRE-HEAT” position and the meter should read battery voltage.

4.Set VOM to measure ohms.

5.Connect the positive (+) meter test lead to the Wire 150 termi- nal of the Pre-Heat Switch (leave Wire 150 connected to the switch). Connect the negative (-) meter test lead to a clean frame ground. Continuity should be measured.

	SW
	BH1-10
	150
	15
	150
150
	B. Schematic
15
A. Pictorial
Figure 7-10. –	Pre-Heat Switch
RESULTS:

1.If battery voltage is not indicated in Step 2, and the battery and fuse are both good, Wire 15 will need to be checked for an open condition.

2.If “Infinity” is measured in Step 5, Wire 150 will need to be replaced.

3.If battery voltage is not present in Step 3, replace the switch.

4.If battery voltage is present in Step 3, proceed to the next test in the Flow Chart.

TEST 20- CHECK FUEL PUMP

DISCUSSION:

The fuel pump delivers fuel to the fuel injector pump. It is powered by Wire 14 when the pre-heat switch is pressed or when the unit is running. Without fuel to the engine, combustion will not occur.

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