4000,S L4-1781cc 1.8L SOHC (MG) (1985)
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1.8 bar on 4 and 5 cylinder engines
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2.5 bar on V6 engines
Troubleshooting tips
Follow these guidelines when troubleshooting a dynamic oil pressure system:
1.
What is the specific customer complaint?
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Does the light come on above or below 2000 RPM?
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How often does the light come on?
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How long does it stay on?
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What are the driving conditions when the light is on?
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What value is displayed on the oil pressure gauge when the light is on (if so equipped)?
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Can the complaint be duplicated?
2.
Check oil level.
3.
Check oil quality. (Is there sludge, contamination or dilution that could affect oil pressure?)
4.
Check oil pressure with an external gauge at idle and above 2000 RPM. It may be necessary to check oil pressure at both switches if one is located
on the cylinder head. DON'T ASSUME THAT THE OIL PRESSURE IS OK. If the vehicle has an auxiliary gauge and it shows sufficient pressure
when the oil pressure light is on, don't assume that the gauge is reading correctly and that the dynamic oil system is malfunctioning.
5.
Check for proper operation of the dynamic oil pressure system.
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engine running less than 2000 RPM with wire to .3 bar oil pressure switch disconnected and grounded
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oil pressure light must flash
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buzzer/chime must NOT sound on vehicles w/o autocheck, must sound on vehicles w/autocheck
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engine running greater than 2000 RPM with wire to the 1.8 or 2.5 bar oil pressure switch disconnected, but not grounded
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oil pressure light must flash
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buzzer/chime must sound
Potential problems to look for
1.
Low oil pressure due to:
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Low oil level
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Diluted or contaminated oil
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Defective oil pump or pressure relief valve
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Mechanical engine problems
2.
Incorrect low oil pressure signal from either oil pressure switch (oil pressure OK).
3.
Low pressure switch circuit has short to ground (light on below 2000 RPM, oil pressure OK).
4.
High pressure switch circuit has open circuit (light on over 2000 RPM, oil pressure OK).
5.
Incorrect low oil pressure indication from oil pressure control module (oil pressure OK, no low oil pressure signals from oil pressure switches).
