I have an 87 Cherokee XJ with the 4.0 L engine I recently purchased. It didn't run when I got it, I looked it over and found that one of the wires that runs to the positive post of the ignition relay box had melted apart. I replaced it and it turned over once, but stopped. I have since bought and installed a wiring harness out of a different 87 Cherokee, and it started up straight away and ran for a while. I turned it on and off a few times, but it died again while it was running, and that same wire was getting hot and smoking. On the positive post of the ignition relay box there are 3 of the fusable links that are connected. On on of the ones with a green and orange wire, the green one is getting really hot, but only with the ignition on. I replaced the ignition switch and found that a couple of the wires there were melted and it appears that the switch arced between them. I made sure all the fuses were correct, and the battery is fully charged. Any ideas or help would be greatly appreciated.

 

I posted a link to the wiring diagram for an 88 cherokee (87 is the same)

Give me a little bit to look it over and I will see if I can give you any advice...

 

By ignition relay box do you mean ignition control module? aka ignition coil

 

No, by ignition relay box I meant starter relay. One of the fusible links gets really hot and actually melted on the wiring harness that was in the jeep when I bought it. It's one of the double wires Green and Orange into the same plug, it is the green wire of that set. It doesn't get hot until the key is turned to run, or start. I replaced the wiring harness with one from a different 87 XJ and it started up fine and ran. I stopped it and started it up again a few times, and then it just stalled and stopped working, and now it doesn't crank anymore. The instrument panel lights turn on, but no go with the starter, and that wire started to get hot again. I used the other harness to trace the wire back to the fusebox and assumed it was the power wire to the ignition switch seeing as how it only got hot when the ignition was on. I pulled out the ignition switch and found that two of the posts apparently had arced or something. The wires were black and the plastic connector had melted. I bought a new ignition switch and cut the ends of those two wires and replaced them with new spades and covered those individually with electric tape to stop them from touching accidentally. I got it all connected again and.... nothing. I'm kinda stumped. I'm wondering if I just haven't traced enough yet. Or if I have fried one of the fusible links with the old ignition switch and simply need to replace it or if it's just shorting somewhere. In looking at your wiring diagramms (I have been looking all over for a decent diagramm, so thanks a ton) I think it is the power wire for the ignition switch, and says it connects to pin B3 of the switch. You wouldn't happen to have a diagramm of the ignition switch would you? Any ideas or suggestions would be greatly appreciated. Thanks.

 

Find out what those wires power. You could have something going bad, or shorting out. Causing the wire to overheat.

 

I would be very interested in the link...if it is still available. Wiring is next on the list for me over the winter. While the Cherokee still runs great, there are various indicators on the instrument panel that turn on and off for no apparent reason. I hope to trace all this stuff and get fixed this winter.

- Jeff -

 

yes me also. A nice wiring diagram is a terrible thing to waste

 

You guys have PMs

Not to be confused with PMS.. lol

 

woah OP i saw your post and i thought someone was on my account or something, our names are almost identical hahaha

 

The 1987 cherokee is different from all other cherokees. There are 2 kinds of 1987 xj's the first half of 1987 and the second half. The way to tell the difference is the first half of 87 has no fuel pump ballast on the harness ( porcelain strip with wires in it). The second half of 1987 does have this ballast. The fusible links are meant to burn up when there is a short in the system. I have rewired my entire 87 xj and mine is the first half of 87.

The most common problem for 87's is the o2 sensor harness. this harness is a separate harness from the one you described above. it connects to the plastic connector top of firewall on drivers side. this harness connects o2 senseor, knock sensor ect. the heat from the exhaust manifold causes wire insulation to wear away and wires to touch. The touching wires will cause your fusible links to blow. Also the plug connecting the back of the fuse box can have bent pins also resulting in fusible links blowing.

Fist pull the o2 sensor harness and unwrap it. Make sure no wires are exposed especially close to where the sensors are located. repair and re-rout the harness to keep the heat away. I use plastic wire loom wrapped in electrical tape. You can buy this at Harbor freight or any auto parts store.

Second disconnect the plug going into the back of your fuse box. This is located under the brake booster. Check for bent pins. Clean and use some electric grease in there and reinstall.

Third check wires by your relays and starter switch. There will be 4 or 5 yellow wires heading towards the main connector on the firewall drivers side. They are very prone to melting together when a fusible link blows.

This is how i fixed mine. Check all 3 because you want to fix the problem not just the symptom.

Good Luck
-Nae

 

I know this is an older thread, but if the link is still available could you send it my way? Just picked up an 2 door 87 xj, and need to replace a lot of wiring

 

87 and 88 have a "C101" connector there by the power brake booster. 89 & 90 don't. I'm pretty sure there is not much else different. (yea, the fuel pump ballast was added only to quiet the pump some, during 87 maybe..)

http://www.scribd.com/doc/11033020/Jeep-Cherokee-1989

HA! Laureto, a guy just pm'd me this morning with problems he solved with PMS.

 

Hello 87XJ2, If you come across a wiring diagram for your 87 I'd like to know the source. I'm in need of one too. So good luck. I'm looking and posting too. I'll let you know if one comes my way.

Ron

 

Hi ron...that waz 2013. My maybe link to diagrams is in another computer...might or might not get to that any time soon.

Cruiser54 has a bunch of stuff on his site that would likely be helpful though. (.com)

 

Sorry I often forget to look at the dates, I found another site with tons of schematics but not cruiser54, thanks for reminding me about his stuff. On my way there.....

Ron