Generac Power Systems GP Series Diagnostic Repair Manual page 55

Table 5-6. LED Notifications
Yellow Short Flash
Yellow Solid
Red Short Flash
Red Solid
Yellow & Red
Long Flashing
Yellow & Red
Solid
No lights
NOTE: A red short flash with a generator shutdown at
any time indicates an elevated level of CO in the area.
The module is functioning properly and is protecting the
operators.
Test 29 – Troubleshooting Engine
Head Temperature Sensor (EHT)
codes 6-7, 6-8)
The engine head temperature sensor (EHT) can be
unplugged from the harness and tested for resistance.
EHT
Figure 5-94. Engine Head Temperature Sensor EHT
Ambient Temperature
0 ºC - 32 ºF
25 ºC - 77 ºF
50 ºC - 122 ºF
100 ºC - 212 ºF
If sensor resistance falls within acceptable parameters
disconnect from harness and perform the following tests
to verify harness integrity.
Use appropriate test probes to test Wire 820G to
1.
ground. A reading of 0 ohms or very low ohms
should be measured.
Use appropriate test probes to test Wire 714 for
2.
voltage to ground. The ECM will need to be active
for this test. Measured voltage should be 4.5–5.0
VDC to ground with an active ECM.
If ground is not measured, or 4.5 VDC is not measured,
the harness will need to be tested for continuity of these
circuits to the ECM. Special care must be used when
working with the ECM connector. Use the wiring diagram
for point-to-point resistance readings of these circuits.
Diagnostic Repair Manual
(Fault
714 ECM-2K
820G SPLICE 2
015046
Resistance
160 ohms ±5%
50 ohms ±5%
18 ohms ±5%
3 ohms ±5%
Section 5 Engine Diagnostic Tests
Test 30 – Troubleshooting Crank
Position Sensor (CKP)
The crankshaft sensor (CKP) can be unplugged from the
harness and tested for resistance.
Coil Resistance
A B
CKP
Figure 5-95. Crank Position Sensor CKP
Use needle type back probes to test the sensor for
cranking voltage and cranking frequency (Hz) while back
probing the sensor Wires 79A (+ Hz signal), 79B (- Hz
signal).
AC Voltage (VAC)
Frequency (Hz)
If the CKP does not read correct output or resistance
replace the CKP. If CKP reads the correct output or
resistance perform a point to point resistance check on
the harness. Verify no continuity to ground on either
conductor. Replace as needed.
Test 31 – Troubleshooting Throttle
Position, Temperature and Manifold
Air Pressure Sensor (TTMAP)
(Fault codes 6-2, 6-3, 6-4, 6-5, 6-6)
The throttle position, temperature and manifold air
pressure sensor (TTMAP) is a 5-wire sensor. The sensor
has a dedicated ground Wire 820G, a dedicated power
supply Wire 820A (4.5–5 VDC), and three output wires:
•
Wire 754 for manifold temperature
• Wire 752 for manifold pressure
• Wire 766 for throttle position.
5
5
4
4
TTMAP
3 3
2 2
1 1
Figure 5-96. Throttle Position, Temperature and
Manifold Air Pressure Sensor (TTMAP)
(Fault code 5-7)
130 ohms ±30%
20
79B ECM-1D
20
79A ECM-1C
Cranking Running
7.1–7.4 37.1–37.3
186–204 appr. 1.43 kHz
752 ECM-2C
820A ECM-3K
820G SPLICE 2
766 ECM-3B
754 ECM-2G
015047
015052
015048
49