Ford Full-Size Cars 1968-1988 Repair Guide



Batteries normally produce explosive gases which can cause personal injury. Do not allow flames, sparks or lighted tobacco to come near the battery. When charging or working near a battery, always shield your face and protect your eyes. Always provide ventilation when working on a battery.


See Figures 1, 2 and 3

Corrosion of the battery terminals and cable clamps interferes with both the flow of power out of the battery and the charge flowing back into the battery from the charging system. This can result in a "no start" condition. If the battery becomes completely discharged, battery life may be shortened. In some cases, a totally discharged battery may not readily accept a charge.

To reduce the need for service and to extend battery life, keep the top of the battery, the battery terminals, and the cable clamps clean and free of corrosion. Make sure the cable clamps are tightly fastened to the battery terminals. If corrosion is found, disconnect the cables and clean the clamps and terminals with a wire brush. Neutralize the corrosion with a solution of baking soda and water. After installing the cables, apply a light coating of petroleum jelly to the cable clamps and terminals to help prevent corrosion.

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Fig. Fig. 1: Battery care may be accomplished with household items like baking soda, and/or special tools like terminal cleaners

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Fig. Fig. 2: The underside of the battery post tool contains a brush to clean the post terminals

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Fig. Fig. 3: Place the tool over the terminal and twist to clean the post


Maintenance free batteries are sealed units, and therefore cannot have their fluid levels checked or adjusted.

Check the battery electrolyte level every month, or more often in hot weather or during periods of extended car operation. The level can be checked through the case on translucent polypropylene batteries; the cell caps or covers must be removed on other models. The electrolyte level in each cell should be kept filled to the split ring inside, or the line marked on the outside of the case.

If the level is low, add only distilled water, or colorless, odorless drinking water through the opening until the level is correct. Each cell is completely separate from the others, so each must be checked and filled individually.

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

Never add electrolyte (battery acid) to the battery, as this could shorten the life of the battery.


See Figure 4

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 when at room temperature.

The specific gravity can be checked with the use of an hydrometer, an inexpensive instrument available from many sources, including automotive 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.

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Fig. Fig. 4: Checking battery specific gravity

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 most maintenance free batteries registers a colored display on the condition of the battery. 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. Consult the label of your battery for the exact colors in which to be aware of.


See Figures 5, 6 and 7

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 clamps 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.

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Fig. Fig. 5: Removing the battery cable with a puller

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Fig. Fig. 6: Spreading the battery cable clamp

Before installing the cables, loosen the battery hold-down clamp or strap, remove the battery and check the battery tray. Clean the tray of any debris, and check it for soundness. The battery tray can be cleaned with a solution of baking soda and water. Use 2 teaspoons of baking soda to every 1 cup of water. Rust should be wire brushed away, and the metal given a coat of anti-rust paint. Install the battery and tighten the hold-down clamp or strap securely. Be careful not to overtighten, which could crack the battery case.

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Fig. Fig. 7: Cleaning the battery cable clamp

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/petroleum jelly or equivalent 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.

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.


Keep flame or sparks away from the battery. The battery emits explosive hydrogen gas, especially when being charged. Battery electrolyte contains sulfuric acid. If electrolyte accidently comes in contact with your skin or eyes, flush with plenty of clear water. If it lands in your eyes, get medical help immediately.

A cold battery will not readily accept a charge, therefore allow the battery to warm up to approximately 41°deg;F (5°deg;C) before charging. This may take 4 to 8 hours at room temperature, depending on initial temperature and battery size.

A completely discharged battery may be slow to accept a charge initially and in some cases may not accept a charge at all. If the battery is in this condition, it should be replaced.

If it has been determined that the battery has begun to accept a charge, it can be charged either using the manual (constant current) setting on the charger or the automatic (adjusting current) setting, if the charger is so equipped.

If the charger is equipped with an automatic setting, the charging rate can be maintained at a safe level. A completely discharged battery will require approximately 2-4 hours to charge to a serviceable state. For a full state of charge, the charge can be completed by a low current rate of 3-5 amps for several hours.

To charge the battery using the manual setting, initially set the charging rate for 30-40 amps and maintain this setting for approximately 30 minutes or as long as there is no excessive gassing or oozing of electrolyte. If there is excessive gassing, reduce the charge rate to a level where the gassing stops. This is especially important with maintenance free batteries as the excessive gassing results in the non-replaceable loss of electrolyte, shortening battery life.

The total charge required will vary with battery size and initial state of charge. As a rule, to bring a discharged battery to a serviceable state of charge, current-time input should equal the battery amp-hour capacity. For example, a 45 amp-hour battery will require a 15 amp charge for 3 hours or a 9 amp charge for 5 hours. To achieve a full state of charge, the charge can be completed by a low constant current of 3-5 amps for several hours.


See Figure 8

Whenever a vehicle must be jump started, precautions must be followed in order to prevent the possibility of personal injury. Remember that batteries contain a small amount of explosive hydrogen gas which is a by product of battery charging. Sparks should always be avoided when working around batteries, especially when attaching jumper cables. To minimize the possibility of accidental sparks, follow the procedure carefully.

NEVER hook the batteries up in a series circuit or the entire electrical system may go up in smoke, especially the starter!

Always follow these precautions:

Be sure that both batteries are of the same voltage. All vehicles covered by this information and most vehicles on the road today utilize a 12 volt charging system.
Be sure that both batteries are of the same polarity (have the same grounded terminal; in most cases NEGATIVE).
Be sure that the vehicles are not touching or a short circuit could occur.
On serviceable batteries, be sure the vent cap holes are not obstructed.
Do not smoke or allow sparks anywhere near the batteries.
In cold weather, make sure the battery electrolyte is not frozen. This can occur more readily in a battery that has been in a state of discharge.
Do not allow electrolyte to contact your skin or clothing.

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Fig. Fig. 8: Connect the jumper cables to the batteries and engine in the order shown

  1. Make sure that the voltages of the 2 batteries are the same. Most batteries and charging systems are of the 12 volt variety.
  3. Pull the jumping vehicle (with the good battery) into a position so the jumper cables can reach the dead battery and that vehicle's engine. Make sure that the vehicles DO NOT touch.
  5. Place the transmissions of both vehicles in NEUTRAL or PARK, as applicable, then firmly set their parking brakes.

If necessary for safety reasons, both vehicle's hazard lights may be operated throughout the entire procedure without significantly increasing the difficulty of jump starting the dead battery.

  1. Turn all lights and accessories OFF on both vehicles. Make sure the ignition switches on both vehicles are turned to the OFF position.
  3. Cover the battery cell caps with a rag, but do not cover the terminals.
  5. Make sure the terminals on both batteries are clean and free of corrosion or proper electrical connection will be impeded. If necessary, clean the battery terminals before proceeding.
  7. Identify the positive (+) and negative (-) terminals on both batteries.
  9. Connect the first jumper cable to the positive (+) terminal of the dead battery, then connect the other end of that cable to the positive (+) terminal of the booster (good) battery.
  11. Connect one end of the other jumper cable to the negative (-) terminal of the booster battery and the other cable clamp to an engine bolt head, alternator bracket or other solid, metallic point on the dead battery's engine. Try to pick a ground on the engine that is positioned away from the battery, in order to minimize the possibility of the 2 clamps touching should one loosen during the procedure. DO NOT connect this clamp to the negative (-) terminal of the bad battery.

Be very careful to keep the jumper cables away from moving parts (cooling fan, belts, etc.) on both engines.

  1. Check to make sure that the cables are routed away from any moving parts, then start the donor vehicle's engine. Run the engine at moderate speed for several minutes to allow the dead battery a chance to receive some initial charge.
  3. With the donor vehicle's engine still running slightly above idle, try to start the vehicle with the dead battery. Crank the engine for no more than 10 seconds at a time and let the starter cool for at least 20 seconds between tries. If the vehicle does not start within 3 tries, it is likely that something else is also wrong.
  5. Once the vehicle is started, allow it to run at idle for a few seconds to make sure that it is properly operating.
  7. Turn ON the headlights, heater blower and, if equipped, the rear defroster of both vehicles in order to reduce the severity of voltage spikes and subsequent risk of damage to the vehicles' electrical systems when the cables are disconnected.
  9. Carefully disconnect the cables in the reverse order of connection. Start with the negative cable that is attached to the engine ground, then the negative cable on the donor battery. Disconnect the positive cable from the donor battery, then disconnect the positive cable from the formerly dead battery. Be careful when disconnecting the cables from the positive terminals not to allow the alligator clips to touch any metal on either vehicle or a short circuit and sparks will occur.