Dead glowplugs draw virtually no current, but
other parts of the vehicle are drawing some
current, up to 8 amps. If any glowplugs are
drawing any current, then the protective
control box is probably OK.
For a good description of how glowplugs cycle
and how to check for proper cycling, refer to
Disconnect negative battery cable before
disconnecting and reconnecting protective
control box harness.
There is battery voltage at the PCB at all times.
Failure to disconnect battery cable will result in
damage to equipment or injury to personnel.
If most or all of the glowplugs are bad, you may
also have a problem with the protective control
box or the glowplug controller which caused
them to go bed (usually they burn out from
being on too long or not turning off at all). After
replacing the bad glowplugs, rerun the
glowplugs test chain paying special attention to
the glowplugs cycling, especially that they turn
OFF when they should.
Replace glowplugs, wires, or harness, refer to
Disconnect ALL the glowplugs.
Disconnect the negative battery cable. Disconnect the PCB
connector harness from the PCB. Reconnect the negative
battery cable. Measure the resistance between pin Din the
engine connector harness of the protective control box and
ground. There should NOT be continuity (resistance reading
off-the-scale). If there is continuity, repair or replace the
Repeat the following for each glowplug
Reconnect the wiring harness to the glowplug while you
repeat the resistance measurement described in step 2.
When you reconnect the wire to the glowplug, the
resistance should drop to between 1 and 2 ohms
(glowplugs are typically 1.6 ohms).
If step a passed;
disconnect the glowplug again, making sure the resistance
goes off-scale again. Repeat step a for the next glowplug.
If step a failed;
then either the glowplug or its wire is no good. Take the
wire off the glowplug again and measure the resistance
from the glowplug to the engine block. If the resistance is
1-2 ohms, then the cable is no good, otherwise replace
the glowplug and check the cable for continuity, just to be
Reconnect the PCB and all wires.