Connect the positive (+) lead of digital multimeter to the battery positive (+) post. Connect the negative (-) lead of the multimeter to the starter solenoid M-terminal.
Engage the remote starter switch. Read and record the voltage. The multimeter reading should be 0.5 volt or less.
If the voltage reading is 0.5 volt or less, go to the Starter Motor - Ground Circuit Component Test
If the voltage reading is greater than 0.5 volt , this is an indication of excessive resistance in the connections, the positive battery cable or in the starter solenoid. Move the digital multimeter negative lead to the starter solenoid B-terminal and repeat the test. If the voltage reading at the B-terminal is lower than 0.5 volts , the concern is either in the connections at the starter solenoid or in the solenoid contacts.
Remove the cables at the starter solenoid B-, S-, and M-terminals. Clean the connections and install the cables. Repeat steps 3 through 6 above. If the reading is still higher than 0.5 volt at the M-terminal and 0.5 volt or lower at the B-terminal, the concern is the solenoid contacts. Install a new starter motor.
If the voltage measured in Step 5 is greater than 0.5 volt , the concern is either the positive (+) battery cable connection or the positive (+) battery cable itself. Clean the positive (+) battery cable connection. If this does not solve the problem, replace the positive battery cable.
Motor-Ground Circuit Test
NOTE: Make all multimeter connections at the component terminal rather than the cable or wiring terminal.
Connect the positive (+) lead of digital multimeter to the starter motor housing. The connection must be clean and free of rust or grease. Connect the negative (-) lead to the negative (-) battery terminal.
Engage the remote starter switch and read the voltage. The reading should be 0.2 volt or less.
If the voltage drop is greater than 0.2 volt , clean the negative (-) battery cable connections at the battery, the body ground connections, and the starter ground connections. Retest.
If the voltage is still more than 0.2 volt , install a new cable. If the reading is less than 0.2 volt and the engine still cranks slowly, install a new starter motor.