Cat d5g ignition diagram with prelube

[pittsburgh cat man]

Sounds like bad oil pressure switch The s terminal wire on starter is probably going to your extra solenoid and a wire one the same post goes to a two terminal oil pressure switch then to s terminal on starter to engage starter after ail pressure is reached sounds like you need a oil pressure switch that closes at 20 psi

 

[Simon C]

Sounds like bad oil pressure switch The s terminal wire on starter is probably going to your extra solenoid and a wire one the same post goes to a two terminal oil pressure switch then to s terminal on starter to engage starter after ail pressure is reached sounds like you need a oil pressure switch that closes at 20 psi

That is where in lies the problem if the starter solenoid needs 20 amps to go, it is very short life for the oil pressure switch. Should check with an old pair of vice grips attached to the oil pump motor cable connection and try a large booster cable onto the vice grips to see if the motor turns over, cause if it doesn't or is drawing too many amps for the surplus solenoid something will burn out fast.
Those systems run best with 2 solenoids installed so that the oil pressure switch is only powering up the switching terminal of a solenoid and won't burn out. The output big cable of a second solenoid powers up the "S" Terminal of the starter.
Hard to explain but could draw it out if nothing else works.
Simon C

 

[Nige]

Well I think I can figure it out if I have the wiring diagram (even if it doesn’t include the prelube). Yes there is a lot of butchery on the wiring harness, I am just trying to figure out at what point it is losing the starter signal. It looks like an aftermarket solenoid has been added above and to the left of the starter, but I am not an expert on these things.

Check your message inbox for a machine electrical schematic.

Cat used systems manufactured by this same "Prelub" outfit on larger tractors and on off-highway trucks. In some cases (large tractors) the prelube pump was actually part of the starter motor. In others (trucks) it was a separate electrically-driven pump like yours mounted on the RH frame rail ahead of the front suspension mounting.

If this system works like the ones I have seen before then it either runs until a certain oil pressure has been reached, or until a certain amount of time has passed. In the case of the latter a timer cuts the power to the prelube pump and sends it to the starter just like it would if the specified oil pressure had been attained. If your system has this timer installed then that could be what's not functioning correctly, or you just may have a bad electrical connection somewhere. See attached.

 

[Simon C]

Check your message inbox for a machine electrical schematic.

Cat used systems manufactured by this same "Prelub" outfit on larger tractors and on off-highway trucks. In some cases (large tractors) the prelube pump was actually part of the starter motor. In others (trucks) it was a separate electrically-driven pump like yours mounted on the RH frame rail ahead of the front suspension mounting.

If this system works like the ones I have seen before then it either runs until a certain oil pressure has been reached, or until a certain amount of time has passed. In the case of the latter a timer cuts the power to the prelube pump and sends it to the starter just like it would if the specified oil pressure had been attained. If your system has this timer installed then that could be what's not functioning correctly, or you just may have a bad electrical connection somewhere. See attached.

So studied that schematic some and it only feeds enough oil to lube the main oil gallery, mains , rods and maybe the cammshaft bearings as the cut out switch is cutting off the ground at 4-7 psi which is more than enough for rollover protection prelube.
On his system I see the picture of the relay so bet the installer opted for an oil pressure switch as it is way cheaper than a cat timer with all the wiring aaasociated with the timer.
Most Forget to Remember that those kinds of pumps can only be used with oil pressure switches that are set very low unless you use 0W40 oil only. Why, because even in Texas if you were using a thick oil on a 30-40 Degree F winter morning the electric motor will draw way more amps than the Small solenoid can handle.
They burn out very fast from the arc when the solenoid contacts release.
If he follows the hose feeding the Oil gallery most likely, he will find a Tee with the pressure switch on the tee being fed the oil from the pump.
Would be good to see another picture.
Simon C

 

[pittsburgh cat man]

The size of the oil lines on the pump plus the gray wire wire tied to the hose is why I said about quick oil change I seem to remember that gray wire going to a plate with a switch and a quick connector that was part of some prelube systems Like he said I'd like to see pictures of hoses

 

[Simon C]

The size of the oil lines on the pump plus the gray wire wire tied to the hose is why I said about quick oil change I seem to remember that gray wire going to a plate with a switch and a quick connector that was part of some prelube systems Like he said I'd like to see pictures of hoses

You could be correct about a quick change oil pump instead of it prelubing. Need more pictures. Hard to see through the crystal ball.
Simon C

 

[Brian Sanders]

I will get more pics in a little while when I am at the machine. I appreciate all the help and info!

 

[Brian Sanders]

Hose from the top of prelude goes over front of engine and down to oil filter housing.

 

[Brian Sanders]

The grey wire that comes from the other side that is tie wrapped to the same hose ends up here also, right beside the hose coming over the top. View attachment IMG_3745.jpeg

 

[Brian Sanders]

So yall may be correct, it could have been for a quick oil change setup or something… but it does build oil pressure before letting the machine start. I have also located what I think is the oil pressure switch that controls prelube. It is wired into the extra solenoid above and left of the starter. I think with the schematic I was sent I can piece it all together and figure out where it’s losing the signal.

 

[Brian Sanders]

Oil pressure switch

 

[Simon C]

Post number 10 shows the sticker stating it has a prelube system on it. Don't think anyone would even get a sticker like that without installing it.
Did you see an oil pressure switch at the end of the hose going into the engine, not the suction end, or elsewhere that has that 2 braid wire that is not OEM attached to it. That pump is controlled by a switch, timer, or a toggle switch of some kind.
Did you check if there is any fuses or resettable breakers that feed that solenoid in your picture in post # 10, .
Simon C

 

[Simon C]

Okay seen your pressure switch and the terminals are not the cleanest. Try to follow the wires from it to either a relay or the S-Terminal of starter is my guess.
Simon C

 

[Simon C]

By the way, if it is starting the pump but not starting the engine , the switch is probably not closing the contacts or they are internally burn't out. Have seen many times.
Simon C

 

[pittsburgh cat man]

Here is a few things for you 1 I'm betting there is a wire coming off batt + on starter to your add on solenoid one of bigger terminals the wire on the other larger terminal goes to prelube motor. 2 when it works is there a pause between the prelube pump running and starter engaging ? If There is there is a controller hiding somewhere 3 the plug by the hose that runs over top of engine is for a remote switch to run lube pump for oil change

 

[Brian Sanders]

i assume the oil pressure switch will short internally when the required pressure is reached? So i should be able to just jumper across it with a short jumper wire for a test. if that works I know its the oil pressure switch. if not, it will remove it from the list of possible issues.

 

[Brian Sanders]

Here is a few things for you 1 I'm betting there is a wire coming off batt + on starter to your add on solenoid one of bigger terminals the wire on the other larger terminal goes to prelube motor. 2 when it works is there a pause between the prelube pump running and starter engaging ? If There is there is a controller hiding somewhere 3 the plug by the hose that runs over top of engine is for a remote switch to run lube pump for oil change

yes, there is a wire from starter to large terminal on extra solenoid (12v hot at all times), other large post goes to prelube motor as power. there is a delay when the key is turned over until starter motor kicks on. the prelube solenoids small posts are connected to oil pressure switch shown in post #31. one side of it or both, I am not sure. I will bypass the oil pressure switch and if machine cranks normally without any delay, I will know its the extra oil pressure switch.

 

[pittsburgh cat man]

Does the oil pressure switch you are looking at have one or two terminals?

 

[Brian Sanders]

Does the oil pressure switch you are looking at have one or two terminals?

two terminals

 

[Brian Sanders]

two terminals

And it’s located here…