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OPS relay install

The OPS has 2 functions.

1. Read Oil Pressure

2. Its a switch itself. (to feed the LP, when there is oil pressure)

It isn't built to specs enough to handle the small current load of the LP and fails. THUS, Instead of replacing them months apart. You simply use the OPS to trigger another RELAY, which carries the current safely. No more monthly OPS replacements.

Not sure how the LP relay plays in this.
 
dangerousdave said:
Not wanting to seem dense, I just want more clarification; If I already have a LP relay, adding another one does what?
If the existing LP relay does not handle the load to the LP, what does it do?

I've never had LP or OPS issues, but I'm not the original owner.
Click to expand...



The Factory relay is only used for crank and some models key on engine off.
After your up and running the power for the LP is fed through the OPS, not the factory installed relay.
By adding an additional relay it take the load of the OPS when wired correctly.
 
dangerousdave said:
Thanx, now it makes more sense.
Could we not rewire to use that excellent relay all the time, maybe some diodes to prevent feedback to the computer?
Click to expand...
IMO, its much easyer to put a relay in the OPS circuit by itself,and add a switch to activate the Relay in case the OPS does give the ghost,also handy to use to pressure up the system before start and when bleeding the filter.:thumbsup:
 
Honestly...I'm going to have to read this 3-4 more times to figure what the heck is going on. I can do household electrical stuff and even add fog and backup lamps on my trucks...but getting into the fuses and relays 1) terrifies me and 2) confuses the heck out of me :(
 
treegump said:
Honestly...I'm going to have to read this 3-4 more times to figure what the heck is going on. I can do household electrical stuff and even add fog and backup lamps on my trucks...but getting into the fuses and relays 1) terrifies me and 2) confuses the heck out of me :(
Click to expand...

C'mon, don't be shy :D

Yes you can do it ):h

Watch the pics at post #1 and 2, + wiring (post #8), schwind says it all.

To make it more clear for you, don't use a purple wire but a grey one instead so you will match stock harness.
  • harness stock grey wire must be cut.
    - the part coming FROM the OPS connects to pin 86 of relay
    - the part (cut) going inside the harness, TO the LP connects to PIN 87 of relay (put a grey instead of purple);
  • pin 85 goes to ground;
  • Pin 30 is 12 volts power source, hot at anytimes. You can splice the orange one from stock harness to OPS for "hot at anytime 12 volts source" or choose to connect directely at one of the batteries, it doesn't mind, result is the same.

To make it more clear to you :
  • When the OPS will have to feed the LP, instead it will trigger the relay applying power to pin 86 powering ON the relay coil.
  • doing so, the relay will close internal switch (connecting pin 87 to 30) and goes "ON" status;
  • 12Volts power will then be allowed to go through the relay, coming from either the orange wire or straigth from the battery (whatever you previously choose) and then to the LP through pin 87
  • when you shut off the engine, and after oil pressure has gone down, internal switch of OPS will release and 12 volts coming from it by grey wire to pin 86 will be off. The coil is not fed anymore and release itself.
    The relay opens switch, cutting circuit which was hold between pin 87 and 30.
    It goes "OFF" status.
    The LP shuts off.

To make it complete, the best is to find a BOSCH relay with internal diode which will avoid inductive kickback spikes, though a stockmarket relay will do it's job too.
You can fab yourself a "BOSCH anti-inductive relay" by adding a diode connected to pin 86 and 85, the anode (+) being connected to pin 86, the cathode (-) to pin 85 of a stock aftermarket no name relay. That's what I did on mine.

inductive kickback spikes are explained here : http://www.allaboutcircuits.com/vol_3/chpt_3/9.html (thanks radioman - post #14 ;) )and here : http://www.opamp-electronics.com/tutorials/inductor_commutating_circuits_3_03_08.htm


Hope that helps ;)

You're done.
 
Help with proper relay

Ok Just to Clarify On the Relay...

Do all relays have pins 86 and 87 on them? I know that the one in my engine bay fusebox for the fuel pump (cranking) has those markings....but i don't cant picture it hanging off the firewall since its basically a block with pins...so what EXACTLY should i be looking for? I read use one from same year truck ( I have 95) but which one? What should I ask for at the parts store or what application is the fuse I'm looking for?

Also I replace my OPS (ac Delco) about 3k miles ago and it cured the problem...but since then the fuel pump is not getting enough current again. I can jump with 12 volts to the obd test port and it runs fine. I have 12volts while running , but it wont run the pump... I guess its not getting enough current through the OPS switch, and to the best of my knowledge the ground for this is the fuel pump itself( but it does have 2 wires ???)....but again staright 12volts run the pump.

Is my OPS Toast again??? PO (my dad) never ever heard the Lift Pump run until I replaces the OPS 3k miles ago ( of course he got it used with 20k and Rebuilt Injection pump...which was prob faulty pmd)


Added Note: Also with engine off and in Drive turning the key to start position activates Fuel pump...so relay is good


Thanks for any help.... Just trying to save my IP.
 
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All aftermarket or general application relays have the markings not all oem do. Sounds like you need to clean grounds and the lift pump does have one. Follow the wire to the frame. OPS could be going bad but 3k would be unusually early. defineately shound do the realy mod
 
What Markings am I looking for?
Geez I hope its not the OPS again...Will have to look harder for the ground wire...I did follow it back into a loom...so i dont know exactly were it pops out.
 
I think AK was referring to the one to the one that goes from the LP to the frame.
 
OPS can easily fail in 3K if you got a cheap parts store version. Even my "HD" OPS from SSD failed in less than a year. You need to do the OPS relay mod and use an ACDelco OPS.

They fail so much faster in OBD1 trucks since it is the sole power source to the LP while running. OBDII trucks run off their LP relay while operating, or the OPS if the relay fails.

Not all relays actually have the 87a pin, but all of the Bosch type have 86 and 87. The LP relay needs the 87A in the middle too. GM labeled the pins different, but they operate the same. The 87A pin is what goes back to your OBD1 port. The 94s and earlier on the firewall did not use that cube box Bosch tpye relay.

Do yourself a favor and get an OPS extension hose from PMDcable.com, just PM Leroy (member burning oil). You can use any hydraulic (or grease) hose with 1/4" mail and female fittings, but then you also have to make sure the fittings are connected with the steel braiding so the OPS is grounded or run another ground to the OPS base. The one from Leroy is very good. Then your OPS can be raised and easily accessable if it ever fails again.
 
I replaced my OPS with Said AC DELCO brand as thats what i read was best...so I'm Hoping it didnt fail already (less than 6months old).

So I have the Cube style relay in my engine fusebox (cranking relay)....Can I just tap into that relay for this to work? I was thinking it would just be easier to buy the right relay and wire it in....but thats me thinking ;)
 
I got mine at the a-Zone, in the lights section. they called it a 4 pole on relay. It would be best to get an additional relay rather than tapping in to that existing one. It only cost like 5 bucks.
 
For the OPS relay mod you dont need an 87A (5-contact) relay type, and I would not tap into the stock relay. You can use stock relay, but then you would need a diode on the line going to the stock relay from the ignition switch, that if it failed might cause starter to engage at any time.

Even the ACDelcos can fail, for said OBD1 reason.

You can use any relay for your mod. One with internal coil diode is preferred.
 
Okay I went to autozone they had a couple for around $5 but didn't appear to have the diode in them...was looking for some kind of squiggly graphic if I'm correct. Gonna check out a stereo install shop and see if they have any there with the diode.

I did notice that either the PO, or dealer had one installed and tapped up under the dash and it had no diode sign on it. I think it was for either the alarm or brake controller...have to investigate further. I'm guessing to er the side on keeping all the electrical circuits safe, I should probably change this with a diode type to.


Also the parts guy said they got all kinds of boxed up ones...but without a specific vehicle they were not goin to let me go thru them all to find the right one. So if anybody can help me there i would appreciate it!






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Ok, I called the electronics supershop and asked if they had any 12v relays with an internal coil diode and they said NO!

....the search continues.....



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Relay info

Okay I think I found a site that has all the info, diagrams, and yes even animation about relays that you'll ever want to know here http://www.bcae1.com/relays.htm

They also call it a Quenching Diode"You can use virtually any type of rectifier or switching diode (i.e. 1N4001, 1N4002, 1N400x... or Radio Shack part #s 276-1101, 276-1102, 276-1103, 276-1104)" that I found at RS web site for $.99 a piece. I'm guessing that any of these could work if I cant find a hanging relay with one built in.

In a earlier post i said i was looking for a squiggly on the relay ...but I'm thinking I should be looking for a triangle with a line balancing on a point.



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