Simple GP controller mod to stop cycling after start

[mblaney]

I made a simple modification to stop the GP controller from cycling after engine start. I think the controller is programmed to keep GP's hot (cycling) for too long after starting for emissions BS; this puts a lot of wear on the controller relay.

My mod is simple enough; I tee'd in an oil pressure switch (part number SP64) and ran the controller white wire through it. (this switch has three connections, NO and NC, you need to use the NC).

I am extremely happy with the results; on a cold start (-20 C) I get about two cycles after starting. When hot, I can start right up (say after a visit to the diesel pump) and the GP is OFF as soon as I have oil pressure.

I figure this reduces GP relay cycles by 60 - 80% and probably adds life to the GP's themselves.

 

[Thewespaul]

Nice mod, now you just need a temp sensor that keeps it from cycling when the truck is warmed up, maybe tie in the ignition source for the controller to the feed for the cold advance

 

[Cubey]

I figure this reduces GP relay cycles by 60 - 80% and probably adds life to the GP's themselves.

A manual button reduces glow plug use by 90-95%. I don't have to cycle them because its warmed up enough most of the time when it's being cranked.

 

[mblaney]

A manual button reduces glow plug use by 90-95%. I don't have to cycle them because its warmed up enough most of the time when it's being cranked.

No way I would consider a manual button... GUARANTEED that anyone else using it will burn up either the GP's or the starter. My wife drives it maybe twice a year ... so that is 16 GP's off the bat... add in a few other occasional drivers...

An operational controller will also instantly tell you when you have a bad GP (short cycling). With a manual system you really have no indication that there is a problem, other than excessive smoke if a cylinder(s) doesn't light off right away.

 

[Tim McKay]

I like this, great idea!
I am new to this truck/engine, so I need to ask: Where do you put the pressure switch on the block? is there a tapped hole with a plug in it somewhere?
I apologize ahead of time for the stupid question

 

[mblaney]

I have a turbo so I tee'd where the oil pressure sensor attaches to the turbo.

If no turbo, then the sensor is at the rear of the block just behind the intake. You could tee into that or using another port elsewhere on the block (search for info, I forget where).

edit:
https://www.oilburners.net/threads/the-best-oil-pressure-port.54791/

 

[Tim McKay]

Great, I will give it a look.
I have definitely noticed the cycles after start. Its just added wear and tear.
Thanks again

 

[laserjock]

I like it! My solution was slightly more archaic. I put a switch in line to kill the controller. On cold start I flip the switch. GP controller does its thing. After it’s warm, turn the switch off and no more GP unless you need them the rest of the day. Saves wear and tear on a lot of things. GP, batteries, alternator, starter (batteries aren’t pulled down from the GP cycling so you get full voltage). One of the better things I’ve done. I considered the temp switch mod. In fact that’s how I was going to wire it it and I traded the temp switch for the in cab. No no mans land (luke warm) hard starts if although if using the stock temp switch it should not be an issue. They do go bad however and you’d have no GP.

 

[franklin2]

I like it! My solution was slightly more archaic. I put a switch in line to kill the controller. On cold start I flip the switch. GP controller does its thing. After it’s warm, turn the switch off and no more GP unless you need them the rest of the day. Saves wear and tear on a lot of things. GP, batteries, alternator, starter (batteries aren’t pulled down from the GP cycling so you get full voltage). One of the better things I’ve done. I considered the temp switch mod. In fact that’s how I was going to wire it it and I traded the temp switch for the in cab. No no mans land (luke warm) hard starts if although if using the stock temp switch it should not be an issue. They do go bad however and you’d have no GP.

Hmmm... a manual glowplug switch only it works the opposite. We are turning on our glowplugs manually for 10 sec, you are turning off your glowplugs with a manual switch.

 

[mblaney]

I like it! My solution was slightly more archaic. I put a switch in line to kill the controller. On cold start I flip the switch. GP controller does its thing. After it’s warm, turn the switch off and no more GP unless you need them the rest of the day. Saves wear and tear on a lot of things. GP, batteries, alternator, starter (batteries aren’t pulled down from the GP cycling so you get full voltage). One of the better things I’ve done. I considered the temp switch mod. In fact that’s how I was going to wire it it and I traded the temp switch for the in cab. No no mans land (luke warm) hard starts if although if using the stock temp switch it should not be an issue. They do go bad however and you’d have no GP.

I considered a manual switch but decided the pressure switch would be much more reliable - don't have to count on occasional drivers remembering how to use it. I don't see the advantage of the temp switch; hot - truck should start right up anyway (so don't need to baby the batteries) and if it is in 'no mans land' it would do more damage than good. To work well the temp switch should be adjustable and set to to some threshold temperature where GP's are not needed. That sounds like a PITA.

Been a week with this mod and I love it!