Onan MDKBH Series, Service Manual

Page: 46 / 90

6-5
GLOW PLUGS
Refer to engine Workshop Manual 981-0533 when
replacing the glow plugs (Figure 6-5).
Note: If a glow plug does not come out after unscrew-
ing it, or the end has broken off, it will be necessary to
remove the engine head. Glow plugs can swell if pre-
heat voltage is greater than 14 volts, such as when a
battery booster is used for starting.
Inspect the glow plugs as follows:
1. Check for B+ at the glow plug terminals during
cranking. If there is no B+ , remove glow plug
relay K3 from its socket, test for proper opera-
tion (p. 9-7) and replace if necessary. Also
check for B+ at relay socket terminal 30, for
continuity between terminal 87 and the glow
plugs and for continuity between terminal 86
and B– (ground). Clean and tighten connec-
tions and replace wiring as necessary.
2. Check for B+ at relay socket terminal 85 while
cranking. If there is no B+ , disconnect connec-
tor P1 (black) from the genset controller (p. 9-1)
and check for a missing, bent or corroded Pin
1 and for faulty wire and repair as necessary.
3. Remove the glow plug bus bar and check for
electrical continuity between each glow plug
terminal and B– (ground). Replace any open
glow plug.
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