Cat d5g ignition diagram with prelube

[pittsburgh cat man]

I don't know if I would want you to jump the wires on the switch the s terminal used to be always white is there a white wire on your add on solenoid ? and what color wire on s terminal on starter

 

[Nige]

I think you could probably combine the machine schematic that I sent to you with the prelube schematic contained in REHS0439 and you ought to be able to figure it out. As I recall prelube was never standard fitment, therefore the electrical side of it was a "stand alone" wiring installation added on to a basic machine. I hope that your tractor follows this pattern and I believe it will have been installed that way.

This may also help. An electrical schematic for a D10R where prelube was an attachment. The prelube timer controls a relay connected direct to the starter.

 

[Nige]

The override procedure for the prelube just popped into my head. Turn the key to the START position and wait for the prelube motor to start. As soon as it does, turn the key to OFF and then straight back to the START position again. That should bypass the prelube timer. Let us know what happens.

 

[Brian Sanders]

The override procedure for the prelube just popped into my head. Turn the key to the START position and wait for the prelube motor to start. As soon as it does, turn the key to OFF and then straight back to the START position again. That should bypass the prelube timer. Let us know what happens.

I think this is controlled by an oil pressure switch instead of a timer, but I appreciate the info, will definitely try it!

 

[Brian Sanders]

I don't know if I would want you to jump the wires on the switch the s terminal used to be always white is there a white wire on your add on solenoid ? and what color wire on s terminal on starter

There is a white wire on the solenoid but it is a small wire and has nothing to do with the starter (I don’t think). There is a white wire connected directly to the starter solenoid that goes to the battery box and is connected to a relay over there. (All info I verified with the wiring diagram). I am in the process of chasing down where 12v is supplied to that relay

 

[Nige]

I think this is controlled by an oil pressure switch instead of a timer, but I appreciate the info, will definitely try it!

If it is like other machines I’ve been around the oil pressure switch is an input signal to the timer module. Take a good look at the D10R schematic that I attached above. This is a “Prelub” brand system that is from what I can see very similar (or maybe identical) to what was installed on larger tractors.

If the oil pressure reaches the set value the timer module immediately activates the starter.

If the oil pressure fails to reach the set value after X seconds the timer module activates the starter.

 

[pittsburgh cat man]

Sorry but why would it try to start a engine that had no oil pressure kind of defeats the purpose of prelude and could cause major failure

 

[pittsburgh cat man]

Might want to check harnesses around the relay in battery box for cat numbers on them

 

[Nige]

Sorry but why would it try to start a engine that had no oil pressure kind of defeats the purpose of prelude and could cause major failure

The way it was explained to me at the time was the system was designed to get some oil into the bottom end of the engine before cranking, not to generate significant oil pressure. The pressure switch was set at 4psi IIRC.

 

[pittsburgh cat man]

If you look at rpm industries it states it will prevent engine for starting with no oil it’s pretty hard to find any thing about the prelude system I remember years ago when we first put them on it was not much more than a box of parts

 

[Nige]

I worked with a number of marine diesel engines where if the prelube pump didn’t raise the pressure to a certain value the engine would refuse to start.

The Prelub brand systems fitted to Cat equipment didn’t work like that, if the oil pressure remained low after starting it depend on the warning system firing off a low oil pressure warning and under certain conditions would shut the engine down.

 

[Simon C]

From what I have read the pump is to just prelube the rods, mains, and maybe cambearings. The engine will turn 10 times per second at idle and the pump will feed everything else. If it can't it will shut down under oil pressure mangement, whether solenoid or computer.
Simon C

 

[Simon C]

The way it was explained to me at the time was the system was designed to get some oil into the bottom end of the engine before cranking, not to generate significant oil pressure. The pressure switch was set at 4psi IIRC.

Correct according to posted info set for 4-7 PSI.
Simon C