Starter motor on car testing

Make of vehicle     Mazda                    Model     323                    Year of manufacture     1984

Is the vehicle equipped with Automatic transmission?     NO
Is the vehicle equipped with any device that requires a power source for its memory?     NO

If the answer to the above question had been yes: -What would you do before disconnect the battery?
I would insert a 9V battery inside it to retain the memory if the car had cigarette light.

1. Preliminary check before carrying out starter circuit voltage drop tests
a) De-activate the ignition or fuel injection system.     YES
b) Has the battery been checked for serviceability?     YES
c) Have you selected the right range on your meter ( digital)?     YES
d) Is the vehicle's transmission in neutral?     YES

2. Check the OCV of the battery 12.40V Percentage of charge 50%

3. Check the available voltage across the battery terminal while cranking.

Refer to page 80 of Gregory's Electrics and Electronics to obtain the voltage specification while cranking, it is the same as when load testing the battery.
Cranking voltage spec     9.5V
Cranking voltage             11.30V     Pass

If the cranking voltage fails the battery must be retested to determine its condition before continuing with this test.
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Starter Motor Circuit Tesing

Now proceed to check the starter circuit for voltage drop as detailed below.

Refer to the diagram below to obtain the correct position at which to take the following voltage drop reading.

a) Check loss between battery positive post and solenoid starter input stud while cranking.

Spec less than 0.20 volts, Volts drop 0.07 V1     Pass

b)Check loss across solenoid main input and output terminal studs while

Spec less than 0.10 volts, Volts drop 0.04 V2     Pass

c) Check loss between battery negative and starter motor body while cranking.

Spec less than 0.20 volts, Volts drop 0.25 V3     Fail

d) Add all the voltage drop together to find maximum voltage drop

Maximum Allowed 0.50 volts, Total volts drop 0.36 Volts     Pass

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Starter Motor Circuit Testing

3. Checking the starter motor current draw

Refer to fig 7-41 page 101 of Gregory's Electrics and Electronics to obtain current draw specification for your vehicle.

Note:

The chart fig 7-41 is for inertia and Pre-engaged starters only see your lecturer if you have a gear reduction starter.

Starter current draw Spec: 125~150 amps.

To check the current drawn by the starter motor it is necessary to use the inductive ammeter ( Clamp meter) .

a) Set the meter on 400 amps DC and push the Zero Button to zero the meter, if the reading doesn't Zero push the Hold Button and repeat the procedure.

b) Once the meter is Zeroed clamp the pick up around the positive battery lead anywhere between the positive terminal and the "B" terminal of the solenoid.

c) Have someone crank the engine and sa it is cranking push the hold button, this will retain your reading.

Starter current draw 105.8amps          Fail

We had two problenms on this starter motor, one is about the starter circuit for valtage drop between battery negative and starter motor body while cranking, the volts drop result higher than Spec less 0.20 volts, we have to clear the terminal then check it again. Other one is about starter current draw it was lower than starter current draw Spec 125-150amps

Starter circuit test     Fail