TEST 3: Voltage Drop Testing The Battery (+) Cable
There's a good chance that you have cleaned the battery terminals or they look clean but there's a good chance that hidden corrosion is keeping full battery power/current from reaching the starter motor.
This problem in turn will keep the starter motor from working and possibly make you think the starter motor is bad (when it isn't).
So in this last test step, I'm gonna' ask you to do a very simple voltage drop test on the battery cable that feeds battery power to the starter motor.
This voltage drop test will let us know if there's any hidden corrosion (on the battery positive cable) that's blocking battery power from reaching the starter motor (this condition is known as a voltage drop).
To further explain what a voltage drop is: a voltage drop is simply a condition in which something (in our case: unseen corrosion) blocks a lot of the battery power (voltage and current) from reaching its destination (the starter motor). When this happens, the starter motor will not be able to crank the engine in your 1.7L Honda Civic even though the battery is in a fully charged state.
OK, to get started, this is what you need to do:
- 1
Place your multimeter in Volts DC mode.
- 2
Attach the red multimeter test lead to the positive (+) battery post. The positive (+) battery post must be clean and corrosion-free.
You may need two helpers for this test step, since someone will have to hold the red multimeter test lead onto the battery positive (+) terminal bolt and someone else inside the vehicle (to crank it when everything is set up). - 3
Place the black multimeter test lead on the starter motor solenoid stud that connects to the battery positive (+) cable (see illustration above).
The orange arrow with the plus (+) sign, in the illustration above, points to this stud.
Maintain the black multimeter test lead in this position throughout the next step. - 4
When everything is ready, have your helper turn the key to crank the engine.
Although the starter motor won't crank the engine, your helper has to turn the ignition switch to start the engine for the voltage drop test to work. - 5
The multimeter should register 0.5 Volts or less (0.5 V = 0 Volts).
If there's a problem in the wire, your multimeter will register some voltage, usually 5 Volts or more.
Let's take a look at what your results mean:
CASE 1: Your multimeter registered 0 Volts (no voltage drop). This result indicates that the starter motor is receiving all of the battery voltage and amperage it needs to crank the vehicle.
This also means that the starter motor is bad, and here's why:
- In TEST 1 you confirmed that the starter motor doesn't work when you apply power to the S terminal wire of the starter motor solenoid.
- TEST 2 you confirmed that the starter motor is receiving the crank signal.
- In this test step you have confirmed that no voltage drop exists on the battery positive Cable.
These 3 test results, taken together, indicate that the starter motor is bad. Replacing the starter motor should solve your no-crank condition.
I'm going to make two more recommendations to you:
- Before removing the starter motor, manually turn the engine using a 1/2 ratchet and the appropriate socket on the crankshaf pulley. This is just to make sure the engine or the A/C compressor have not locked up and causing the no-crank condition.
- -AND-
- Bench test the starter motor after removing it. This is a super easy test to do and you can find this article by clicking here: How To Bench Test A Starter Motor (Step by Step) (at: easyautodiagnostics.com).
CASE 2: Your multimeter registered 5 Volts or more. This result tells you that a voltage drop does exist and this is not a good result.
The good news is that this can easily be corrected, since a voltage drop is always caused by some sort of corrosion issue on the battery positive Cable or terminals or the battery positive post.
The solution is to thoroughly clean the battery positive post and the battery positive (+) terminal (both the end that attaches to the battery positive post and the end the connects to the starter motor solenoid).
After cleaning, try cranking the engine. If it cranks and starts, no further testing is required.
More 1.7L Honda Civic Test Tutorials
You can find a complete list of Honda Civic tutorials in this index: 1.7L Honda Civic Index Of Articles.
Here's a small sample of the tutorials you'll find in the index:
- How To Test The Crank Sensor (2001-2005 1.7L Honda Civic).
- Maintenance Required Light Reset (2001-05 1.7L Honda Civic).
- How To Do A Cylinder Balance Test (2001-2005 1.7L Honda).
- How To Test Trouble Code P0141 (2001-2005 Honda 1.7L).
- How To Test The TP Sensor (2001-2005 1.7L Honda Civic).
- How To Test Trouble Code P0135 (2001-2003 Honda 1.7L).
If this info saved the day, buy me a beer!
