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Wiring a relay to the oil pressure sending unit?

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Old 04-16-2012, 06:53 PM
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Default Wiring a relay to the oil pressure sending unit?

I've searched this forum like crazy for a couple days and if this one was answered somewhere already, I couldn't find it. Sorry if it's here somewhere and thanks ahead of time for any tips or nods in the right direction.

First, here's a look at my engine compartment if that helps:


I've been playing around with making a Hotsabi HHO booster. (btw, Please don't reply if you have opinions about HHO. I'm past that stage already and looking forward to running my experiment. Also, I'm just asking a [hopefully] simple wiring question.)

Here's my Hotsabi so far just for curiosity's sake:




I'm planning on using an auto relay, 30 amp breaker, 15amp fuse, kill switch and ammeter, plus I'll probably have to buy an EFIE at some point.

It's going to mount real nice next to the evap cannister.



I read that I should wire this hydroxy booster into something that is only hot when the engine is actually running.

After studying my Chilton's guide here for awhile it seems to me that I could wire the low voltage part of the relay to the Oil Pressure Sending Unit.

You can see it there above the oil filter.

So, my question is can I do that? Does that thing send enough voltage through the wire going to the gauge that it would power a relay?

Thanks!
Old 04-16-2012, 07:08 PM
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Whoops, I should also mention that I'm still teaching myself basic electrical wiring and I'm a beginner so if I don't make sense in that dept. that's why. Thanks for your patience.
Old 04-16-2012, 07:12 PM
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pretty sure sender works by ground not volts
Old 04-16-2012, 08:28 PM
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Stay away from the oil pressure sending unit.

If you look at the plug on the coil there is a (dark green/orange) wire that is the 12V feed from the ASD relay. This will provide exactly what you are looking for.
Old 04-17-2012, 11:09 AM
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Originally Posted by ETexas XJ
Stay away from the oil pressure sending unit.

If you look at the plug on the coil there is a (dark green/orange) wire that is the 12V feed from the ASD relay. This will provide exactly what you are looking for.
Whew, I'm glad I didn't have to try and get that oil pressure thingy off to get my tester at it. It looks like some kind of special nut. I would have had to try plumbing pliers.

Thanks for the tip. I'll start looking between the coil and the ASD relay.

The only thing I've been able to dig up online about the ASD relay though is a lot of people asking for help because their Jeeps won't even start and people seem to point them towards the ASD relay.

Also from Yahoo:
"Positive feed to the coil comes from the ASD relay in the power distribution center then though fuse 20 (20A) also in the PDC. That's the dark green/orange wire. Relays should be listed in the PDC lid.

The ASD relay is activated for a couple of seconds when the ignition is first turned on and also when the engine is being cranked or is running. The computer supplies the ground to trigger the coil via the gray wire."

That's a bit enlightening. I had hoped to tie this HHO unit into something that happened to be hot when the engine is actually running, but NOT something that is vital.

So, my new question is, "Is that possible? Or will I need to tap into something vital to get at anything that's hot while the engine is running only?"

In the meantime I'll start looking into this ASD thing. It might be fine if I'm very careful, eh?

I"m having a heckuva time finding any diagrams or pictures of this ASD thing online. I ordered the High Performance Jeep Cherokee XJ Builder's Guide last week and it should show up any day now.

Do you guys know if it'll have a decent diagram of this ASD relay area or should I be looking someplace else?

Thanks! You guys rock.
Old 04-17-2012, 11:30 AM
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The ASD relay is activated for a couple of seconds when the ignition is first turned on and also when the engine is being cranked or is running.
Also, I thought this was the reason that it isn't a good idea to wire into the fuel pump... because it comes on for a second or something to prime when the engine is not running.

Isn't there anything non-vital that gives off a little voltage only when the engine is running?
Old 04-17-2012, 12:22 PM
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what is your average mpg first? would like to see the results from this...btw, i would just take power from the steering column and put it to a switch/relay. turn it on manually...?
Old 04-17-2012, 02:13 PM
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Originally Posted by hankthetank
what is your average mpg first? would like to see the results from this...btw, i would just take power from the steering column and put it to a switch/relay. turn it on manually...?
Thanks but no, it's not safe to turn it on/off manually.

And, some extra mpg would be nice but I'm really doing it to give the engine some love. It's supposed to drastically increase the life of the engine, clean out deposits and generally make it run better. I'll have to get an EFIE later to see any mpg increase with the fuel injectors.

You guys inspired me to start a thread about the whole thing.
https://www.cherokeeforum.com/f67/93...ooster-132595/

Last edited by lucknuts; 04-17-2012 at 03:51 PM. Reason: cross ref
Old 04-17-2012, 04:31 PM
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ignition wire...blue/white on your steering column.
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