OPS relay install

[Schwind]

WOW, this thread has taken on a life of its own. seem like a fairly simple project has become a chore.
JMO

Yes this mod was for pre 96. There was no redundancy on the older curcuit. The main reason for the mod was to reduce the electrical load on the OPS from the LP. (current draw)

I have had no problems from the OPS since I did this mods in the original form. matter of fact, I haven't had any problems out of my truck in a long time.

 

[jrsavoie]

'm still using the bad OPS on the Tahoe. It puts out enough juice to engage the relay and the gauge works.

 

[normburns]

Could a stock type relay be used in place of the aftermarket relay, maybe just change the source of the relayed voltage, to ensure the pump gets a full 12vdc? I have a relay, p/n 412210, with the same plug, the same pinout on the schematic... has anyone else considered/looked into this idea? Does anybody know what the actual trigger voltage is, in case the OPS is not giving 12vdc?

 

[Burning oil]

A stock type relay is the better choice IMO, its weather tight and meant for underhod temps.
Trigger is 12v also.
Im developing a Plug and play "kit" for just the LP. GPs you'ed be on your own, but I am also developing a GP override kit too.

 

[normburns]

A stock type relay is the better choice IMO, its weather tight and meant for underhod temps.
Trigger is 12v also.
Yes, I knew the intended trigger is 12vdc, what I am wondering is... what is the low side? I have seen relays trigger with a couple of volts, as long as it is enough to engage the electro-magnetic that kicks the relay into energized mode.

Im developing a Plug and play "kit" for just the LP. GPs you'ed be on your own, but I am also developing a GP override kit too.

Ahem, will it be here by this afternoon, if not, I will have to fake it... :hihi:
What I intend to try first, is to shoot 12vdc through the stock harness to the LP, and see if the pump is even working, I don't know that I have ever heard it run., then I will go from there. I sure am glad this thread is here, as it has given me a couple of ideas on how best to accomplish this, and keep the mod clean at the same time.

 

[jrsavoie]

I like to use relay sockets. That way if you have to pull a relay, you do not have to worry about getting the wires back on correctly.

Leroy,
I really like the double lift pump relay option. I like the priming aspect. It helps reduce the impact of small leaks.

There are links here to places to purchase relay sockets & to the schematic for the double relay update. I got the proper relays from the local dealership for cheaper than the relays I got - that didn't work from the local Nappa

 

[Burning oil]

Norm, the trigger side is the low side.

 

[Darkrider]

Im developing a Plug and play "kit" for just the LP. GPs you'ed be on your own, but I am also developing a GP override kit too.

I would def be interested in this! My sierra currently has the ops completely bypassed and triggers the Lp by the key being switched on. Ideally I would like to keep it like that but add a relay to draw power directly from one of the batteries.


Sent from my SGH-T959D using Tapatalk

 

[normburns]

Okay. I replaced the LP. Not remarkably impressed so far. I did no bleeding, so I was not surprised when it took a bit, and some smoking to get going. I was not impressed AT ALL by my initial results. Then I took it down the road a ways, and it is definitely better. Better power, smoother when running... but it still isn't quite right, not like is has been for over 3 years. I am still inclined to think the problem is the voltage driving the LP. I did not change the OPS... took a look and said to myself: "Self, shall we tackle this?" Upon this query, self said" "No, hell no!"

Now then, I have a source for battery power, I have no wiring diagram, and I want to modify the circuit so that the trigger voltage is "key switched 12vdc", and the relayed voltage is 12vdc, from the battery, SO:
1st, What color wire do I cut for the trigger voltage? My vision ain't the greatest, so I will do better with a wire color, than with a pin number.
2nd, where do I find a switched 12vdc nearby?
3rd, what wire do I cut for the battery supply voltage?

I THINK the purple one is power to the pump, is that right? That is one I should not have to mess with then.

I appreciate the help. I have to use the truck in about 2 weeks to move a little crippled up (even more than me) fellow about 15 miles. If I can get the truck running right, then I can use the big trailer, and cut down the number of loads I have to make.

Yesterday was not a good day. Getting up and down during the LP change process had me stiff. Then, just to add insult to injury, when I gassed the mower so I could mow... I grabbed the wrong can, and put in some #2... yep, diesel. Oddly enough, the mower did not want to run on it. Who would have thought that? Got that taken care of, did the mowing, and by then I had topped off the batteries on the truck (if they are down even a little, it does not like to cooperate). She fired up with lots of smoke, white smoke. Let her even out, and took her down the road. Better, but not quite right though, hence the above questions.

 

[Burning oil]

I would def be interested in this! My sierra currently has the ops completely bypassed and triggers the Lp by the key being switched on. Ideally I would like to keep it like that but add a relay to draw power directly from one of the batteries.


Sent from my SGH-T959D using Tapatalk

I see you tried to PM me. Try again please or email me.

Okay. I replaced the LP. Not remarkably impressed so far. I did no bleeding, so I was not surprised when it took a bit, and some smoking to get going. I was not impressed AT ALL by my initial results. Then I took it down the road a ways, and it is definitely better. Better power, smoother when running... but it still isn't quite right, not like is has been for over 3 years. I am still inclined to think the problem is the voltage driving the LP. I did not change the OPS... took a look and said to myself: "Self, shall we tackle this?" Upon this query, self said" "No, hell no!"

Now then, I have a source for battery power, I have no wiring diagram, and I want to modify the circuit so that the trigger voltage is "key switched 12vdc", and the relayed voltage is 12vdc, from the battery, SO:
1st, What color wire do I cut for the trigger voltage? My vision ain't the greatest, so I will do better with a wire color, than with a pin number.
2nd, where do I find a switched 12vdc nearby?
3rd, what wire do I cut for the battery supply voltage?

I THINK the purple one is power to the pump, is that right? That is one I should not have to mess with then.

I appreciate the help. I have to use the truck in about 2 weeks to move a little crippled up (even more than me) fellow about 15 miles. If I can get the truck running right, then I can use the big trailer, and cut down the number of loads I have to make.

Yesterday was not a good day. Getting up and down during the LP change process had me stiff. Then, just to add insult to injury, when I gassed the mower so I could mow... I grabbed the wrong can, and put in some #2... yep, diesel. Oddly enough, the mower did not want to run on it. Who would have thought that? Got that taken care of, did the mowing, and by then I had topped off the batteries on the truck (if they are down even a little, it does not like to cooperate). She fired up with lots of smoke, white smoke. Let her even out, and took her down the road. Better, but not quite right though, hence the above questions.

If your going to be cutting wires see post #1

 

[Darkrider]

I see you tried to PM me. Try again please or email me.

PM Sent...hopefully it got through this time lol

 

[jrsavoie]

Check post #68 for a schematic for the dual relay upgrade.

Check my posts for the 94. I think I actually took pictures of that.

It sounds to me as if you have some issue other than your lift pump not running right.

DID you use the lift pump for a 1993? Maybe there should be another thread for further diagnosis