Ford 2600 warning lights

Jeffstewart1980 · Apr 3, 2016

I have a 1979 ford 2600 3 cylander diesel with an alternator and regulator. The warning lights come on when the key is turned as they should but do nothing when the engine is running even when they are unplugged. And when you unplug the oil sensor with the key on but not running the air restriction and oil sensor light goes off.

Jeffstewart1980 · Apr 3, 2016

After looking further into it. It seems that the diode running to the
lamps is bad. Anyone have any experience with this or ideas to fix it?

rvirgil_KS · Apr 4, 2016

Is your alternator charging? Does battery voltage increase when you start the engine?

Are you referring to a diode connected between oil pressure and air restriction lamps? If so it's purpose is to have both oil pressure and air restriction lamps glow when there is an oil pressure drop, but only the air restriction lamp to glow when the air cleaner flow is restricted. Both lamps should go out when you disconnect lead from oil pressure sender. I suspect that diode is not your problem.

Oil pressure sender switch is closed when engine is off, thus providing ground to the lamps. When engine starts and oil pressure gets to prescribed level the switch opens and with no ground the lamps go out. Air restriction sensor switch is open during normal operation and closes with restriction to ground the air lamp.

Jeffstewart1980 · Apr 4, 2016

You are correct after taking the diode off and testing it it tested good. My altanator is charging when the motor is running I get 12.56 from battery with the engine off and 14.1 with it running. Am I correct in my thinking that if I unplug the sensors while the engine is running that the lights should come on?

rvirgil_KS · Apr 4, 2016

No. One side of the oil and air lamps are supplied power and the oil lamp is grounded through the oil pressure sensor. The diode acts as a one way switch and allows the oil pressure sensor to also ground the air lamp. When engine runs and system comes up to normal operating specs, the oil sensor opens the ground connection and turns off the lamps. When you unplug the sensor you are also opening the ground connection so the lights should not come on.

The air sensor is normally open and closes with an air restriction. This grounds the air lamp to turn it on but the one way action of the diode prevents the oil lamp from coming on.

Jeffstewart1980 · Apr 4, 2016

Thak you guys for all the help I have my instruments working as expected. I really appreciate it.

Ford 2600 warning lights

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