Gentherm 5220 Operating Manual page 72

28142 Rev 15
Check the Spark Electrode
The spark electrode serves two roles; it ignites the incoming fuel-air mixture in order to start
the TEG, and it also senses a flame while the TEG is running. The ceramic rod insulating the
metal electrode is very brittle and prone to breakage. A broken electrode may short to ground
or spark in an unintended location. If the spark gap is set improperly, the TEG may fail to
ignite, or the electrode may not sense flame properly. Follow these steps to verify that the
spark electrode is functioning properly:
1. Remove the electrode and inspect it for any cracks in the ceramic rod. If any cracks
are found, the electrode must be replaced.
2. If it is not damaged, slide the electrode back into position through the burner-back
until it stops (hits the far wall of the burner), then pull it back 3.2 to 6.4 mm (0.125
to 0.250 in.). If the spark electrode is too close to the burner-back, the sparks may
not deliver enough energy for successful ignition. If the spark electrode is too far from
the burner-back, the SI system may not provide enough total energy for arcing to
reliably occur.
3. Check that the fuel hand valve outside the TEG is closed.
4. Unplug the orange wire connectors from the terminals on the pressure switch and
then short them together. Arcing should occur in the combustion chamber (making a
clicking noise) at the rate of five sparks per second.
5. If consistent sparking occurs at a rate of 5 audible sparks per second, the SI system
is functioning properly.
Check the Pressure Switch
The fuel pressure switch is used by the SI module to sense fuel pressure. A faulty pressure
switch may manifest as a TEG that won't start. Follow these steps to check the pressure
switch:
1. Remove the two wires from the pressure switch and connect a multi-meter across the
pressure switch terminals, set to measure resistance (ohms). See Figure 32 and
Figure 33.
2. With no fuel pressure reading on the gauge, check that the resistance measured
across the switch is near infinity, which indicates the switch being open. Replace the
pressure switch if necessary.
3. Disconnect the solenoid valve by removing the connector. This will prevent any fuel
from flowing.
NOTE:
Switch should open at pressures below 6.9 kPa (1 PSI).
4. Provide fuel pressure to the switch by opening the manual shutoff valve.
5. Check the resistance measured across the switch is near zero, which indicates the
switch being closed. Replace the pressure switch if necessary.
Gentherm Global Power Technologies
TROUBLESHOOTING
Page 66