The starter has three electrical connections:
1) White wire from CAS that powers the starter solenoid. When start button is pressed, voltage on the white wire activates the internal starter motor relay that allows high amperage battery voltage to power the starter motor.
2) Large red cable directly from battery that powers the starter motor when the starter motor relay is activated by the starter solenoid.
3) Battery ground for both the starter solenoid and starter motor provided by the starter casing via the engine and chassis grounds.

What you refer to as the "solenoid stud" is the starter motor stud.

 

Steps 1-4 in the LoadPro instructions are the first tests you should do for both the starter solenoid and starter motor.

Measure voltage across the two battery posts and note it.

Step 1: Disconnect the starter solenoid connector and the large red starter motor cable.

Steps 2-3 for starter solenoid circuit. Touch red LoadPro probe to white wire pin in starter solenoid and black probe to clean metal area of starter. Make DC voltage reading.
Step 2-3 for starter motor circuit. Touch red LoadPro probe to large red cable and black probe to clean metal area of starter. Make DC voltage reading.
Are both voltage reading identical or very close to the battery voltage you noted? If so, proceed to step 4.

Step 4: In each of the two configurations tested in steps 2-3, press the LoadPro button to check for voltage drops. Post the voltage drops.

Step 5: If voltage drops are detected in the circuits, determine whether + or - sides of the circuits are responsible for the drops.

 

This is what I did with the Load Pro for the starter solenoid circuit. I disconnected the plug from the starter solenoid and put the LoadPro in it (black grounded to chassis) and measured battery voltage when pressing start button. When applying the load via the LoadPro I got a tiny reduction in voltage.



The rest of the voltage drops were done without the load pro. Just the multimeter.

 

Do the LoadPro tests below and post all of the measurements.

Measure voltage across the two battery posts and note it.

Step 1: Disconnect the starter solenoid connector and the large red starter motor cable.

Steps 2-3 for starter solenoid circuit. Touch red LoadPro probe to white wire pin in starter solenoid connector and black probe to clean metal area of the starter casing. Make DC voltage reading.
Step 2-3 for starter motor circuit. Touch red LoadPro probe to large red cable and black probe to clean metal area of starter casing. Make DC voltage reading.

Post all the voltage readings measured above.

Step 4: In each of the two test configurations in steps 2-3, press the LoadPro button to check for voltage drops. Post the measured voltage drops.

Step 5: If a voltage drop is detected in one or both circuits, post the drop(s) and then determine whether + or - side of the circuits is responsible for the drop(s).

 

If you do the LoadPro starter solenoid and starter motor tests exactly as described and find NO VOLTAGE DROPS, then your starter is bad.

 

Notes:

1. To do LoadPro test of the starter solenoid circuit, you must insert the key and press start with brake pedal depressed (clutch pedal depressed for manual transmission).
2. To do LoadPro test of the starter motor circuit, you DO NOT NEED to insert the key and press start with brake pedal depressed.

 

okey dokes I will try again with the load pro.

 

When you complete the LoadPro tests, you should know what the problem is in your starter circuit.

 

(By the way, thanks so much for your help)

Reporting LoadPro tests

1. Battery terminals: 13.04 (no load)

2. Starter solenoid circuit plug and starter body (I had to use some 25 foot alligator leads because I need to read the multimeter in the cabin as I press brake -automatic trans- and START, since I'm alone)




While pressing Start, foot on brake:
Unloaded: 12.21v
Loaded (with Loadpro button): 12.01v = 0.20V drop

Not pressing Start
Unloaded: 0.037 (not pressing Start, but Key On Engine OFF or in our case gauge pod lights are on but engine is obviously not running)
Loaded (with Loadpro button): 0.000 (not pressing Start, but Key On Engine OFF) = 0.037 drop (this test was not needed..silly me)


3 Starter wire from battery and starter body

End of wire from battery wrapped in a cloth so it wouldn't contact the body and ground itself.



While pressing Start, foot on brake:
Unloaded: 12.25
Loaded (with Loadpro button depressed) : 12.08 =0.17v drop

Not pressing Start (not sure this test was needed)
Unloaded: 12.37
Loaded (with Loadpro button depressed): 12.21 =0.16v drop

 

Nice work, lex! Your test results clearly point to a bad starter.

 

Thanks! I still don't understand why I was getting 10.7 volts at Terminal 50 when backprobing...

 

Post #23, right?

What are the two meter probes touching in the picture? What 2P connector is that? And the test was only the multimeter without LoadPro, right?

 

no, here:

How can I get 12+ volts at the end of the circuit and 10.7v here midway through the circuit?

 

What specific connector are you probing in the picture to read 10.7V? The circuit diagram shows 2 connectors (X2498 and X9331) between CAS and the starter solenoid connector (X9135).

 

 

In the picture, you are probing two pins in a disconnected connector (either X2498 or X9331), right?

Does the connector have two wires and one of them is white? What color is the other wire?

 

yes that's the white wire that goes to the starter solenoid.

I thought the other wire was a ground wire but maybe that is incorrect.

I assumed they both went to the starter solenoid but now that I think about it that's not true because the starter solenoid grounds to the engine.

 

You are correct! That's why you did not read 12V.

 

haha...indeed only one of those wires on that connector make it to the solenoid....not sure where the other goes.

 

The test light was another option but required 2 people. Unfortunately I had to test on my own.

 

Is your starter problem fixed?

For your starter issue, the test light would not have worked to test the starter motor circuit because you did not have a convenient way to test that part of the starter circuit under load. In contrast, the LoadPro was able to yield clear answers because it loads the circuit.

 

Why not? He just connected to the negative battery terminal and tested for current under load at S and B terminals and the chassis ground.

I just received the starter from FCP Euro. Will install on weekend.

 

He was able to load the starter motor circuit. You were not.

 

I loaded it, it just didn't start. CAS was working and sending signal, no?

 

I agree that the test light method likely would have yielded an interpretable result on the starter solenoid side of your starter circuit because you could hear the solenoid click when supplied with voltage, indicating a current draw.

However, it's less clear that the test light method would have yielded an interpretable result on the starter motor side because there was no hint that the motor drew any current when the solenoid clicked. For example, if the motor had an internal open circuit, no current would flow through it, and you would not detect a voltage drop on the + or - side of the circuit, even if there was excess resistance present there. If you didn't know that the voltage drop test requires current flow to draw conclusions, you would incorrectly interpret the results to indicate that the + and - sides of the motor circuit were good.