[ct157167]

I have a 1990 Cherokee that, when you turn the key to start, makes the relay center by the battery pop and will not crank the motor. The batter is fully charged and all cables are tight. Could it be a bad relay?

[vaquaro]

Try the oldest trick in the book .....Get some one to operate the key/ignition for you and try taping the starter motor case with a small hammer , this may work to jar the rotor or brushes off a "flat spot" and allow the motor to crank....once its running ,head staight to the parts store and buy a new starter motor.

[Carl48]

Follow the advice about tapping the starter motor. If that fails to get you going, get a voltmeter and see if you have 12 volts at the small terminal on the starter motor when somebody turns the key to the "start" position (be careful, the engine may try to start). If you see 12 volts, everything up to the starter motor is OK and you need to replace the starter motor if it did not crank.