Section 7

DIAGNOSTIC TESTS

2.If engine cranks in Step 3 when Wire 17 is grounded, but will not crank when the Switch is set to “START”, replace the Start- Stop Switch.

3.If the Start-Stop Switch (SW1) failed any part of Steps 5 or 6, replace the switch.

4.If engine will not crank when Wire 17 is grounded, proceed as follows:

a.Use a jumper wire to connect the circuit board's Wire 17 (pin location J1-6) to ground. If engine does NOT crank, proceed to Test 25.

b.If engine cranks now, but would not crank in Step 3 of the procedure, check Wire 17 for con- tinuity between the circuit board and Start-Stop Switch. If “Continuity” is not measured, repair or replace Wire 17 between the engine control board and the Start-Stop Switch.

5.For Problem 9 (Section 6), if switch tests GOOD, go to Test 30.

TEST 25 - CHECK POWER SUPPLY TO WIRE 56

DISCUSSION:

If battery voltage is available to the Engine Controller board in Test 23, then DC voltage should be delivered to Wire 56 when the Start-Stop Switch is set to “START” (Test 24). This test will check to see if the circuit board is delivering battery voltage to the Wire 56 terminal.

PROCEDURE:

1.Set a VOM to measure DC voltage (12 VDC).

2.Disconnect Wire 56 from its Starter Contactor Relay terminal.

3.Connect the meter positive (+) test lead to Wire 56, just discon- nected. Connect the other test lead to frame ground. No volt- age should be indicated.

4.Actuate the Start-Stop Switch to its “START” position. The meter should indicate battery voltage. If battery voltage is pre- sent, stop the procedure.

5.Connect the VOM positive (+) test lead to Wire 56 (Pin Location J1-1) at the Engine Controller Circuit Board. Connect the other test lead to frame ground.

6.Actuate the Start-Stop Switch to the “START” position. The meter should indicate battery voltage.

RESULTS:

1.If battery voltage was measured in Step 6, but not in Step 4, repair or replace Wire 56 between the Engine Controller Circuit Board and Starter Contactor Relay.

2.If battery voltage was not available in Step 6, replace the Engine Controller Circuit Board.

3.If battery voltage is available in Step 4 but engine does not crank, go to Test 26.

TEST 26- CHECK STARTER CONTACTOR

RELAY

DISCUSSION:

If battery voltage is available to Wire 56 but the engine won't crank, the possible cause could be a failed Starter Contactor Relay.

PROCEDURE:

1.Set the VOM to measure resistance (“R x 1” scale). Remove Wire 0 from the Starter Contactor Relay (SCR). Connect one meter test lead to Wire 0, and connect the other meter test lead to frame ground. “Continuity” should be measured. Reconnect Wire 0.

2.Set the VOM to measure resistance (“R x 1” scale). Disconnect Wire 16 and Wire 13 (Wire 13 is 12VDC isolate from ground) from the Starter Contactor Relay (SCR). Connect one meter test lead to an SCR terminal, and connect the other meter test lead to the remaining SCR terminal. “Infinity” should be mea- sured. Set the Start-Stop Switch to “START”. The meter should now read “Continuity”.

Short to Ground:

3.Set the VOM to measure resistance (“R x 1” scale). Disconnect Wire 56 from the Starter Contactor Relay (SCR). Connect one meter test lead to the SCR terminal from which Wire 56 was just removed. Connect the other meter test lead to a clean frame ground. Starter Contactor Relay coil resistance of 155 ohms should be measured. If “Continuity” is measured a short to ground exists.

Note: Current draw of the Starter Contactor Relay coil at nominal voltage is approximately 80ma.

Figure 7-19. – Starter Contactor Relay

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Generac Power Systems 65, 55, 75 manual Test 26- Check Starter Contactor Relay, Set a VOM to measure DC voltage 12 VDC
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