Hopefully this doesn't get long-winded. I have a '98 Cherokee that had an aftermarket radio when I got it. I recently pulled an OEM Radio at a junk yard and put it in, temporarily wire-nutting the wires back to their original 7-pin counterparts that the original owner still had dangling behind the radio. The display lit up, and I could get a quiet bit of sound while jeep is in on position, but upon startup the sound disappears. (Mind you, the aftermarket radio was working fine, just didn't like the look)

I went in and messed with I believe the ground wire, and for a precious few seconds the radio was playing loud and clear, until I pushed it back into place. Thinking the 7-pin connector had a bad connection for the ground wire, I bought new ones and wired them up, but I'm back to the same problem of either no sound or just static on FM. Sometimes I can get AM channels even when FM doesn't work.

I put in a CD and it does work so I think it must either be a problem in the radio itself, a problem with the antenna, or the grounding maybe but I'm not sure the best way to troubleshoot my options. Any help is appreciated, here are a few pictures to give an idea of what I'm working with.

 

Hard to figure out what's going on with that rats nest but there's supposed to be a separate ground going to the chassis of the radio ( in the oe configuration it's a black wire going to one of those male push on connectors on the back of the radio.
If you look at that connector diagram you'll note that there's no negative/ground for the power to the radio and the radio is mounted in plastic.

 

Yeah I'm not looking to have anyone trace these for me, I'm just interested in anyone's knowledge about how I should be troubleshooting this. I think I have read about the black wire being the ground but you are right that the diagram has the mute wire connecting to the black wire.

Could grounding be the problem if it partially works? I would've thought it wouldn't work at all if it wasn't grounded. Its just confusing because it worked perfectly for a couple minutes so I think it must be one of the wires, but I'm not sure if there's a way I could use my multimeter to see if they are all doing their jobs

 

I've spent a lot of time getting that same radio sorted out in my 2000 and it now works great.
a couple things.

1) I have no idea what the " mute wire" you are referring to is. If it matters the pin/wire on the connector identified as park dims the display when the headlights are on.

2) it's possible that the thing is somewhat grounded through the antenna wire shield but it would be a pretty poor ground.

3) again, al least before someone started cutting wires there was a separate black wire that connects to the chassis. Look around for it. If you can't find it try connecting a wire from a solid vehicle ground point to the chassis and see what happens.

4) and of course the radio could be messed up...but you need that ground.

 

There is no Ground wire in the grey/black connector. It was separate and to the body of the factory radio.

The static on FM and AM points at the antenna connector. Make sure its securely in place.

 

So if the black wire is the ground, do I need to attach a lug to the end of it and find a place to screw it to the body of the radio or how did it attach from factory? I had attached it the the last wire on the gray connector because I just assumed all the wires in the harness were supposed to go to the connectors.

 

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Like I said before. The black wire normally has a female push on connector that is pushed on one of the male connector tabs on the back of the chassis. If someone cut off the connector on the black wire you'll need to crimp one on.

Who knows what you might have done by grounding whatever wire you connected the black wire to..

 

While I feel dumb for not having realized it earlier, I have now crimped a push on connector to the ground and connected it to the chassis, and the good news is​​​​​​ that now the speakers are not quiet when I play a CD, the volume is now working properly.

The FM and AM are still not working, but whereas pushing seek a couple days ago would've had the radio continually loop through every station, now pushing seek increments it by 0.4 every time. I have done a continuity test on the antenna and it seems to be good, but if there are any other tests I should run to pinpoint the problem as within or without the radio, I would love to hear them.

 

There's a chance you damaged something in the audio circuit for the fm/am output side.

 

https://www.allpar.com/threads/fixin...-guide.228476/

https://www.cherokeeforum.com/f2/rad...egular-114706/

Ok, here are 2 things to look at, the first gives you an idea of what's going on in there, the second is a recent thread on the forum I found useful.

The unit has 3 basic sections. The top is the CD player, middle is tape player, bottom is radio, amp and power supply. In most cases the sections are connected with ribbon cable.

My problem had been intermittent display. I tried reflowing some solder joints and cleaning a bunch of connectors but the solution turned out to be the funky jail bar connection between the lower and middle board.

Keeping in mind the radio could be unfixable toast, and the fact that your aftermarket radio works with your antenna,if it were mine...and this isn't my first rodeo on this-stuff, I would:

Pull out the radio but keep everything connected

Tune the radio to the frequency of a very strong local station( yeah I know the radio doesn't work, look up the frequency,)

Make sure the volume is turned up all the way
wiggle the antenna wire while it's plugged in..any luck?

Don't get nuts but wack on the left side of the case with something like a plastic screwdriver handle...any luck?

If no luck with above, or the wacking produced a response, consider trying, with great care, to clean the jailbar connector in the forum thread... keep in mind doing more harm than good is a possibility depending on your experience.
but the connector has a history of problems.

BTW wd40 is not a contract cleaner, nor is dielectric grease