The starter on a 1990 Nissan pickup is mounted to the transmission housing and can prevent the truck from starting when it goes bad. The starter can be removed and bench tested to ensure it is faulty before spending a lot of money on a replacement starter. The bench test can be done at most automotive parts stores. Most stores sell brand new starters and remanufactured starters. The latter are rebuilt and cost less than a new starter.
Open the hood to disconnect the battery. Unbolt the negative and positive cable from the battery with a socket wrench. This will isolate the electrical power from the vehicle.
Chock the back wheels and ensure the parking brake is set. This will prevent the truck from rolling back when it is raised.
Place a jack under the front crossmember. Raise the truck high enough off the ground to place jack stands under the front doors. Lower the truck onto the jack stands.
Crawl under the passenger side of the truck and locate the starter bolted to the transmission bell housing. The starter is secured by two bolts.
Unbolt the two bolts with a socket wrench, freeing the starter from the truck. Tap the starter with a hammer to free the seal created from being mounted to the truck.
Unbolt the positive and negative wires from the top of the starter with a socket wrench. Wrap masking tape around the positive cable to help identify the correct wires during installation.
Bolt the positive and negative wires to the battery. Tighten with a socket wrench to ensure the wires are securely mounted to the starter.
Position the starter to the truck. Start both bolts by hand. Do not tighten either bolt until both are started.
Tighten the bolts with a socket wrench. Ensure the starter is tight by shaking it by hand to ensure it is secure.
Raise the vehicle with a jack to remove the jack stands. Lower the truck to the ground once the jack stands are removed.
Connect the battery by bolting the positive cable to the positive terminal. Bolt the negative cable to the negative terminal.
Start the truck to ensure the starter is working adequately. Close the hood.
