SFurie

I haven't had a Jeep for a while but I picked up a 1987 Cherokee Limited back in July. I'm sitting at almost 400K miles original and for the age it's running great but ever since the weather turned colder it's been slower and slower to start. I replaced the alternator in July and the starter checks out. In October I replaced the smaller car battery at 300 CCA with a new 575 CCA battery but saw little improvement. Everyone keeps saying I need a new battery but I just did that! I'm looking for ideas on what else it could be because, quite frankly, the electrical system is so completely FUBAR it needs to just be redone. Is there something else I can check out or do I really need more CCA? I can't afford to Just Empty Every Pocket into re-wiring right now so I'm fixing as I go!

I've read through related threads here but didn't find anything that seems applicable. Thank you for any suggestions you can throw my way!

Roler

Welcome to the forum!

With your Renix Jeep , you might want to check Cruiser54's Mostly Renix Tips for a whole lot of excellent advice and things to do.
Keep in mind that Renix Jeeps take a longer cranktime in general, compared to other jeeps and especially other cars. Increasing CCA's will likely not change this.
Members with renix's will likely chime in soon with advice

Edit: here is the link
https://www.cherokeeforum.com/f51/cr...x-tips-153657/

cruiser54

From the link, and an excellent place to "start".

Renix Ground Refreshing

The Renix era XJs and MJs were built with an under-engineered grounding system for the engine/transmission electronics. One problem in particular involves the multiple ground connection at the engine dipstick tube stud. A poor ground here can cause a multitude of driveabililty issues, wasted time, failed emission tests, and wasted money replacing components unnecessarily.

The components grounding at the dipstick tube stud are:

Distributor Sync Sensor, TCU main ground, TCU “Shift Point Logic”, Ignition control Module, Injectors, ECU main ground which other engine sensors ground through, Oxygen sensor, Knock Sensor, Cruise Control, and Transmission Sync signal. All extremely important stuff.

The factory was aware of the issues with this ground point and addressed it by suggesting the following:

Remove the nut holding the wire terminals to the stud. Verify that the stud is indeed tightened securely into the block. Scrape any and all paint from the stud’s mounting surface where the wires will attach. Must be clean, shiny and free of any oil, grease, or paint.

Inspect the wire terminals. Check to see that none of the terminals are crimped over wire insulation instead of bare wire. Be sure the crimps are tight. It wouldn’t hurt to re-crimp them just as a matter of course. Sand and polish the wire terminals until clean and shiny on both sides. Reinstall all the wires to the stud and tighten the nut down securely.

While you’re in that general area, locate the battery negative cable which is fastened to the engine block just forward of the dipstick stud. Remove the bolt, scrape the block to bare metal, clean and polish the cable terminal, and reattach securely.

Another area where the grounding system on Renix era Jeeps was lacking is the engine to chassis ground. There is a braided cable from the back of the cylinder head that also attaches to the driver’s side of the firewall. This cable is undersized for it’s intended use and subject to corrosion and poor connections at each end.

First off, remove the cable end from the firewall using a 15mm wrench or socket. Scrape the paint off down to bare metal and clean the wire terminal. Reattach securely.
Remove the other end of the cable from the rear of the head using a 3’4” socket. Clean all the oil, paint and crud from the stud. Clean the wire terminal of the cable and reattach securely.

A suggestion regarding the braided cable:
I prefer to add a #4 Gauge cable from the firewall to a bolt on the rear of the intake manifold, either to a heat shield bolt or fuel rail bolt. A cable about 18” long with a 3/8” lug on each end works great and you can get one at any parts store already made up. Napa has them as part number 781116.

A further improvement to the grounding system can be made using a #4 cable, about 10” long with 3/8” terminals at each end. Attach one end of this cable to the negative battery bolt and the other end under the closest 10mm headed bolt on the radiator support just forward of the battery. Napa part number 781115.

For those of us with Comanches, it’s very important to remove the driver’s side taillamp assembly to access the ground for the fuel pump. Remove the screw holding the black ground wire. Scrape the paint from the body and corrosion from the wire terminal. Reattach securely.

If you want to upgrade your grounds and battery cables in general, contact Jon at www.kelleyswip.com. He makes an incredible cable upgrade for a very reasonable price.


Revised 03-04-2013

SFurie

Thank you for the ideas! I am going to try the suggestions about the ground as soon as the weather clears, hopefully this weekend. I had checked to make sure the ground wire was connected but didn't think to check how good of a connection it was. The previous owners really did a number on the electrical (yay for amateur amp wiring). I visited the site link to check out new cables but got a 404 on the PDF list; there's a message about the site being migrated to a new domain so I'll keep checking. I'll update once I can get out there.

Thanks again for the help!