Mirage642

The patient is a 2000 Cherokee, 4.7l, 4WD. During the past couple of months, it occasionally would not start. 9.5V would show on the instrument gauge and @12.5 at the battery. Attempting to start it would cause the guages to swing through a complete cycle, sometimes you would get a clicking noise (as in a relay re-setting itself) and sometimes you wouldn't. The motor would not crank. After a few minutes of rapidly cycling the key in the switch, she'd fire right up like nothing was wrong. Today, it finally drained the battery. Tried jumping it only to have the motor turn over a few times before it stopped cranking. Before we jumped it, I checked the battery cables and the positive cable was very hot.

I've heard of these getting a short in the dash but I have been able to find out what causes the short. Any ideas before I throw several hundred dollars at it?

Mirage642

Had the thing pulled home by a friend and let it sit today. Slapped a battery charger on it and let it sit for several hours at low charge. Tried to start it and it only clicked. The gauges wobbled, the speedo and tach both stayed all the way around. Pulled battery and tested it by itself. 100% Whatever is cooked is cooked.

Kazman

Well I wouldn't start to just replace things just yet. 1st off check "all" your connections. Battery terminals, the alternator, the starter and to the fuse box for any corrosion or bad connections. Very common things that gets overlooked when charging and starting issues arise.

Mirage642

We haven't had a chance to tear into it yet. We do plan to put a load test on it and see if we can narrow it down to whatever is causing it. Will hold off from replacing things at random.

Mirage642

Tore into it tonight. Battery did checkout OK. The starter was the next suspect on the agenda and was pulled. Attempts to jump it resulted in a zero response. Further tear down continued into the solenoid. Having a healthy battery charger and numerous test have determined the solenoid was a oversized fishing weight. With starter assembly removed, all lights gauges, windows, etc. worked perfectly with a nice 12.+ voltage showing on the gauge. To the parts store I go.

Mirage642

Arrggghh! Replaced starter and solenoid because I couldn't get only the noid. Same problem still. Talked to a mechanic and he said it sounded like the starter. Explained it was new. He said have the battery and the starter tested and if that didn't work call him on Monday.

I wondered if the fuse link went bad but those usually toast themselves pretty good and are obvious when they go.

Kazman

Sorry to say it, but it sounds like you have a bad ground issue. Check "ALL" connections. The ones to your alternator, the passenger fender, the tranny, all of them... Oh and not to be rude.. find a new mechanic. Any and all "good" mechanics would know to look for a bad connection on all related parts before replacing anything

Mirage642

No, you're not rude and I appreciate your help. We tested things pretty throughly when we pulled the starter. Like I said, when the starter was removed all the gauges showed normal. That would indicate to me at least that the ground was good to the block and chassie. I will have the bat and starter checked tomorrow and also start looking for loose connections. This one is challenging the people who know.

The real trip is that the positive cable get VERY HOT when we try and get it started. That again tells me that there is a ground. May not be in the right place but she's grounded.

seed

There must be resistance(in the current flow) to create the heat you're feeling in the positive cable so thoroughly check that as well for any corrosion/damage/bad connections. Other than that i'm with kazman..and definitely make sure the battery is good.

Mirage642

Ok, starter and battery have been tested and pronounced Good. Unscrewed ground connections on the block and body, cleaned and retightened. Tried running jumpers from the battery negative to the body and block still no go. Just clicks.

Thinking about seed's comment about the positive cable and tested it. Shop manual says the cable should only show 0.2 volts between the battery and the starter noid. Bumping the ignition showed only 0.1 but when you held it down for 2-3 seconds it quickly jumped up to 0.35 and 0.4. That, to me would explain the heat in the postive cable and that not enough juice was making it to the starter. I have not tested the ground cable connections yet.

Mirage642

Checked the ground and that meet the shop manual specs. Pulled the postive cable and went online to find a replacement cable. HOLY SMOKES!!!!!!!!!! I haven't been able to find a positive cable online and the ones I've found for the 4.0 are not cheap. Not looking forward to stopping in at the stealership.

Mirage642

It's fixed.

After talking with a friend he said he could make a harness but that he could also conduct a load test on it. While doing that he noticed the amount of corrosion inside the clamp. He cleaned it up and then it passed further load testing. I took sandpaper to the batter post and noticed the black corrosion where I hadn't noticed it before. Cleaned it all up and hit the starter. Turns over like it was a new one. Another experience to learn from.