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Relays on my '87 MJ


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Howdy all,

Does anyone know the function of the four relays under the hood? My MJ has some interesting mods to them; The relay closest to the windshield had been spliced to another fifth relay? Not at all sure of what the P.O. intention was with this mod. He also has made some splices from and into the wiring harness near that area as well. It has two additional red wires spliced from the wiring harness, one runs back to my fuel pump and the other into the firewall. Not sure where it goes from there yet. I bought this MJ from an estate sale (the owner's son said it had been in storage for about 9 mos). It ran fine, but added new tires, used cored out radiator, changed fliuds and lubed all the chassis points and no probs for the year I've owned it. Until a few weeks ago when it started this "only runs on starter fluid" scenario. Up until that time I thought, if it aint broke..you know? I had the relays checked at napa and the only bad relay was the fifth added one. Oh, btw, I found my cps. was under the truck blindly copping a feel and couldn't find it. I looked down from above, moving wires, etc. and lo and behold...tada...there she was. Will have to wait to check til my bod isn't screaming at me, but wanted to know what the relays were about in the meantime. I would also like to trace these rerouted wires, but I not sure I want to go that route. It also needs a new exhaust manifold as it's cracked up near where the last down tube meets the header assembly. Also have to install new P. steering unit as it leaks badly and a few minor glitches. Oh, before I forget, there seems to be two female ports near the relays (I assume these are for diagnostics?) true? false?

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From right to left there are 5 relays. The last relay (starter relay) is not colored in this pic. It's the one that pretty much everything including batt, alt and all those fusible links. I believe it powers the whole harness.

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OK Paradise....normally my mj has five relays?...sorry was under the impression my year mj should only have four.

 

four are all in a row, but the fifth is spliced from the first relay and also has splices into portions of the wiring harness.

 

wondering if this could be the root of all my gremlins with my mj.

 

thx 4 responding Paradise

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I took another look at your post with pic of relays and yes it helped greatly,,,THX

 

guess some clarification is needed though, I was not counting the starter relay in with the other ones,

 

I have five relays (cubed in shape) and the starter relay...ok? the fifth (cubed relay) looks to be an add-on as it is clip wired into the wiring harness and from the first relay closest to the windshield.

 

Wish I could figure out how to get my pic from photobucket on here, that would help I am sure,

 

Too tired to go on riht now, been on one of my many insomnia nights

 

Thx agn Paradise and later gator

 

Ron

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I have a couple of added relays on my XJ for lights, and to moderate the voltage draw on the A/C (the mechanic did that one and explained it to me but :dunno:) and only one on the MJ, just for extra lights. There are only 4, besides the starter relay, anything else would have been added.

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No, the relay I added on the MJ was just for extra lighting. I have yet to dive in to the A/C. I've gone thru the whole system during the build and everything is up and running. I did replace all the other relays though, with new.

 

On my XJ the A/C would cut out (not actually turn off just blow hot) after it ran for 10 or so minutes, then it would miraculously blow cold again...my mechanic rewired another relay just for the A/C which solved THAT problem for good.

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