4-52 4181383 First Edition
ELECTRICAL
4
Instrumentation Circuit
Lamp and Audible Alarm Check Circuit
The control module provides a lamp and audible alarm check circuit. When the key switch is turned to the run position
the control module turns on the following for approximately 3 seconds:
• Glow plug light
• Hydraulic filter pressure light
• Hydraulic oil level light
• Horn (chirping)
After the lamp and audible alarm check circuit times out, the alternator and oil pressure light remains on because the
engine is not operating. If any of the lights fail to turn on check the light bulbs.
Symptom: Engine oil pressure light does not turn on.
Symptom: Engine oil pressure light stays on with engine running.
Symptom: Glow plug wait light does not come on.
Probable Cause Remedy
Faulty engine oil pressure switch. With the key switch in the off position, check continuity between engine oil pressure
switch and ground. Continuity must be indicated. If continuity is not indicated, replace
engine oil pressure switch.
Faulty engine oil pressure light switched
power circuit.
With the key switch in the run position (engine off), measure voltage between engine oil
pressure light org/wht wire terminal and ground. Voltage must be approximately 12
VDC.
Faulty engine oil pressure switch circuit. Check continuity between engine oil pressure switch terminal and engine oil pressure
light terminal (blue wire). Continuity must be indicated.
Faulty LED. Substitute the LED with a known good LED.
Probable Cause Remedy
Low engine oil pressure. Check engine oil pressure.
Faulty engine oil pressure switch. If engine oil pressure tests good, replace engine oil pressure switch.
Probable Cause Remedy
Faulty control module output circuit. With key switch in the run position, check control module glow plug lamp output LED. If
the LED turns on for approximately 3 seconds, check continuity between control
module glow plug lamp output terminal J2-11. Continuity must be indicated.
If the LED does not turn on, substitute the control module with a known good control
module.
Faulty switched power circuit. Measure voltage between glow plug lamp Org/Wht terminal and ground. Voltage must be
approximately 12 VDC.
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