Jeep CJ/Scrambler 1971-1986 Repair Guide




See Figures 1, 2, 3, 4, 5, 6, 7 and 8

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Fig. Fig. 1: Battery maintenance may be accomplished with household items and with special tools like this post cleaner

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Fig. Fig. 2: The underside of this special battery tool has a wire brush to clean post terminals

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Fig. Fig. 3: Be sure to clean the battery cable clamps before installing them on the battery

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Fig. Fig. 4: Place the tool over the terminals and twist to clean the post

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Fig. Fig. 5: The specific gravity of the battery can be checked with a simple hydrometer, which can be purchased at most auto parts stores

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Fig. Fig. 6: If the battery cells are low, fill each to the bottom of the ring with distilled water

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Fig. Fig. 7: Battery specific gravity readings

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Fig. Fig. 8: You can use a small puller to remove the battery cables

Loose, dirty, or corroded battery terminals are a major cause of "no-start." Every 3 months or so, remove the battery terminals and clean them, giving them a light coating of petroleum jelly when you are finished. This will help to retard corrosion.

Check the battery cables for signs of wear or chafing and replace any cable or terminal that looks marginal. Battery terminals can be easily cleaned and inexpensive terminal cleaning tools are an excellent investment that will pay for themselves many times over. They can usually be purchased from any well-equipped auto store or parts department. Side terminal batteries require a different tool to clean the threads in the battery case. The accumulated white powder and corrosion can be cleaned from the top of the battery with an old toothbrush and a solution of baking soda and water.

Unless you have a maintenance-free battery, check the electrolyte level (see Battery under Fluid Level Checks in this section) and check the specific gravity of each cell. Be sure that the vent holes in each cell cap are not blocked by grease or dirt. The vent holes allow hydrogen gas, formed by the chemical reaction in the battery, to escape safely.


The cold power rating of a battery measures battery starting performance and provides an approximate relationship between battery size and engine size. The cold power rating of a replacement battery should match or exceed your engine size in cubic inches.


The correct level should be at the bottom of the well inside each cell opening. The surface of the electrolyte should appear distorted, not flat. Only colorless, odorless, preferably distilled, water should be added. It is a good idea to add the water with a squeeze bulb to avoid splashing and spills. If water is frequently needed, the most likely cause is overcharging, caused by voltage regulator problems. If any acid should escape, it can be neutralized with a baking soda and water solution.

Avoid sparks and smoking around the battery! It gives off explosive hydrogen gas. If you get acid on your skin or eyes, rinse it off immediately with lots of water. See a doctor immediately if you get acid in your eyes! In winter, add water only before driving to prevent the battery from freezing and cracking.

Original equipment batteries with the ganged caps are often chronically wet on top, causing a lot of corrosion in the battery tray. The problem is insufficient venting. Solve it by removing the caps and drilling a tiny vent hole for each cell through the top of the cap.

If water is added during freezing weather, the truck should be driven several miles to allow the water to mix with the electrolyte. Otherwise the battery could freeze.

At least once a year check the specific gravity of the battery. It should be between 1.20-1.26 in. at room temperature. Clean and tighten the terminal clamps and apply a thin coating of petroleum jelly to the terminals. This will help to retard corrosion. The terminals can be cleaned with a stiff wire brush or with a terminal cleaner made for the purpose. These are inexpensive and can be purchased in most any decently equipped parts store.


At least once a year, check the specific gravity of the battery. It should be between 1.20 in.Hg and 1.26 in.Hg at room temperature.

The specific gravity can be check with the use of an hydrometer, an inexpensive instrument available from many sources, including auto parts stores. The hydrometer has a squeeze bulb at one end and a nozzle at the other. Battery electrolyte is sucked into the hydrometer until the float is lifted from its seat. The specific gravity is then read by noting the position of the float. Generally, if after charging, the specific gravity between any two cells varies more than 50 points (0.50), the battery is bad and should be replaced.

It is not possible to check the specific gravity in this manner on sealed (maintenance free) batteries. Instead, the indicator built into the top of the case must be relied on to display any signs of battery deterioration. If the indicator is dark, the battery can be assumed to be OK. If the indicator is light, the specific gravity is low, and the battery should be charged or replaced.


Once a year, the battery terminals and the cable clamps should be cleaned. Loosen the clamps and remove the cables, negative cable first. On batteries with posts on top, the use of a puller specially made for the purpose is recommended. These are inexpensive, and available in auto parts stores. Side terminal battery cables are secured with a bolt.

Clean the cable lamps and the battery terminal with a wire brush, until all corrosion, grease, etc., is removed and the metal is shiny. It is especially important to clean the inside of the clamp thoroughly, since a small deposit of foreign material or oxidation there will prevent a sound electrical connection and inhibit either starting or charging. Special tools are available for cleaning these parts, one type for conventional batteries and another type for side terminal batteries.

Before installing the cables, loosen the battery holddown clamp or strap, remove the battery and check the battery tray. Clear it of any debris, and check it for soundness. Rust should be wire brushed away, and the metal given a coat of anti-rust paint. Replace the battery and tighten the holddown clamp or strap securely, but be careful not to overtighten, which will crack the battery case.

After the clamps and terminals are clean, reinstall the cables, negative cable last; do not hammer on the clamps to install. Tighten the clamps securely, but do not distort them. Give the clamps and terminals a thin external coat of grease after installation, to retard corrosion.

Check the cables at the same time that the terminals are cleaned. If the cable insulation is cracked or broken, or if the ends are frayed, the cable should be replaced with a new cable of the same length and gauge.

Keep flame or sparks away from the battery; it gives off explosive hydrogen gas. Battery electrolyte contains sulfuric acid. If you should splash any on your skin or in your eyes, flush the affected area with plenty of clear water. If it lands in your eyes, get medical help immediately.


Battery chargers are relatively inexpensive, easy to use and available at any retail outlet that sell auto parts. For the average vehicle owner, a 6 amp charger is more than sufficient. Always follow the manufacturer's instructions when using the charger.

Keep flame or sparks away from the battery! It gives off explosive hydrogen gas, while it is being charged.