Note: This is provided for information only. Perform at your own risk. If you are inexperienced, get help from an experienced technician. Instructions shown are for Jeep ZJ (Grand Cherokee) but basic steps are the same for all vehicles.
The stock Jeep ZJ positive cable has a large molded connector that has both the battery cable (the battery +) and the start solenoid wire molded into one. It makes it easy to hook up the wires, but impossible to replace just the battery cable without modification. In addition, some Jeeps have a negative “Y” cable with one side going to the block and the other goes to another large molded connector at the back of the alternator. Once again that makes it impossible to replace the cable without buying the entire expensive assembly from Jeep or making some sort of modification. Important: Always use appropriate safety measures (safety glasses, jack stands, etc). Use the correct tools for the job.
Installation and Modification Steps:
Step 1: Disconnect both battery cables, removing the negative battery terminal first, being careful not to short circuit the battery. Always disconnect ground cable first and connect it last. See our Battery Cable Tips and Tricks page for more info.
Step 2: Separate the battery cables from the wiring harness by carefully cutting any tape holding it to the wire harness.
Step 3: Jack up the Jeep enough to get to the starter and rest vehicle on appropriate jack stands. DO NOT rely on the jack to hold up the vehicle while you work on it.
Step 4: Remove the nuts holding the molded connector to the starter.
Step 5: Cut the small wire as close as possible to the molded connector
Step 6: Strip the end of the wire and crimp a new “blue” (16-14 ga) ring terminal on the end of the small wire and heat shrink (use a heat gun or blow dryer).
Step 7: Replace small wire on the starter and replace the nut.
Step 8: Disconnect the wire going from positive battery terminal to the under-hood fuse block at the fuse block and alternator if wire also goes there and new alternator wire is included in the kit.
Step 9: Remove the old positive cable from the vehicle (there should not be anything connected to it)
Step 10: Connect the new positive battery cable to the starter making sure to use the starter lug cover.
Step 11: Route the positive cable to the battery being careful to avoid any hot or moving parts that could damage the cable.
Step 12: Connect the positive cable to the battery and to the fuse block.
Step 13: If an alternator wire is included with your kit, connect it from the alternator to fuse block.
Step 14: Remove and replace negative cable following the same basic procedure (separate from the harness, remove from the block and inner fender, replace) – use the “Y” kit if needed. See Jeep Y cable modification page
Step 15: Using electrical tape, loom or wire ties, secure any hanging or dangling wires away from hot or moving parts. Neatness counts.
Step 16: Lastly, connect the negative battery terminal being careful not to short out the battery with a wrench.
Jeep “Y” negative battery cable modification:
I don’t know why Jeep used that cable but apparently, it’s an impossible cable to find. Below is what I did on my 1997 Jeep Grand Cherokee and it seems to be working great. In fact, I think the voltmeter went up slightly when I hooked up the new ground cable.
Step 1: Disconnect the negative cable from the battery.
Step 2: Disconnect the other end of the negative cable from the stud on the engine block.
Step 3: Using a box cutter, carefully cut the tape that holds the corrugated loom and cables together.
Step 4: Locate the “Y” in the negative cable and cut the wire going to the alternator as close as possible to the “Y”. Crimp a heavy-duty #8 gauge 5/16 lug (#10 gauge is too small) on to the end of the wire coming from the alternator (the one you just cut – a 310 gauge crimper works OK). Apply heat sink to seal the connection.
Step 5: Plae the ring end of the new battery cable on the engine ground stud, then install the alternator ground wire (with the new end) and replace the nut.
Here is a sketch of what it all looked like when done.
The chassis ground on our cables is a few inches longer than stock for ease of installation.
The cable is a little long at 30 inches but that is what the factory cable was.