OK, hear are my multimeter results.
All testing done with starter mounted and connected and NSS bypassed using a lead between the C and D pins in the harness connector on the engine side.
1) Battery tested 12.3 volts on both battery posts and at battery cables just past the clamps. Voltage dropped to 12.15 volts when I had the under-hood lamp plugged in, BTW. Is that voltage drop normal or relevant?
2) I attached one end of a jumper cable to the solenoid trigger post. I attached the other end of the jumper to the (+) battery post. Still a no-crank. I believe this is essentially the same test as using a remote starter set-up to bypass the battery cable and get direct current to the solenoid, which should induce crank if the starter is working, correct?
3) I next connected the (+) meter probe to the solenoid trigger wire, not the trigger post. This was actually on the flat metal plate that the solenoid stud passes through. I connected the (-) meter to ground on the vehicle frame. I had my wife turn the key. I received a 10.6 volt reading on the multimeter. This is with the under-hood light on, BTW. So this would indicate that current is actually getting through the battery cable to the solenoid, correct? This should also verify that current is NOT being interrupted by either the NSS (which of course is bypassed anyway, in this scenario) or the ignition switch. So I can eliminate those two as culprits.
4) I next attached the (+) meter probe to the (+) battery post. I touched the (-) meter probe to the constant (+) stud on the solenoid. I had my wife turn the key. I got a 0 volts reading on the meter, which indicates no voltage drop. So this means the starter is receiving enough current.
5) Just by way of double checking, I attached the (-) meter probe to the (-) battery post and alternated the (+) meter probe between both on the trigger stud and wire and the constant (+) stud and wire. With the key off, both the trigger wire and the trigger stud read 0 volts. Both the (+) stud and the (+) wire gave 12.2 volts. So this confirmed for me that the cable from the battery were in fact sending current to the solenoid at the (+) stud. It also confirms that the connection between the wire and the stud is good.
6) I then repeated test 5 except that I had an assistant turn the key to the start position several times. Both the trigger wire and the trigger stud gave 10.9 volts when the key was turned. Both the (+) wire and the (+) stud gave fluctuating readings which dropped as low as 11.5 volts. So this would seem to indicate that, under load, the battery is still sending enough juice to the trigger stud to induce a crank if the solenoid/starter were working properly. It would confirm that the trigger wire is working fine, as is the connection between the wire and stud. It would also confirm that the NSS (bypassed at present) and the ignition switch are NOT interrupting the current to the solenoid, else it wouldn't get its 10.9 volts.
So this means it MUST be a problem within the solenoid/starter, correct? Even though it was somehow testing fine at the parts store. So that means that the starter is failing under load? But I am hearing nothing at all from the starter when the key is turned with me right under it jabbing it with a probe. There's horrible joke potential there, I know.
So how does that happen? How can it test fine on the bench and be as dead as door nail on the other side of the studs when it is actually mounted to the motor? If it fails under load, I would at least expect to hear something try to engage or some mechanical noise from inside the starter housing. But I hear nothing from the starter at all.
And to be clear, the motor is not seized. I was able to turn the crankshaft bolt rather easily with my ratchet and also when tugging on the serpentine belt by hand.
I am OK with replacing the starter. But it does have me scratching my head over why the previous two times this has happened, it tested fine immediately upon removal yet waited some time before it started working again when re-installed only to quit again under the same circumstances one and two years later.
Does that heater control valve only drip when I run the heater inside? And that's why it only happens in the late fall when the weather turns cold? And why it runs fine all spring and summer? Is it possible that coolant in the starter causes the starter to foul, but then operate once the vehicle sits (no drips) and the starter dries out? But if so, how could it test fine on the bench? Wouldn't it still be just as fouled inside from the coolant that has soaked in?
I'm just trying to make sense of it all.
Hey James , thought I would reply to yesterday's post of your multimeter testing .
1. I would say the battery is good and voltage drop probably normal with test lamp used.
2. To use a remote starter , one lead to the starter's big stud with the battery positive already connected for power ( starter mounted on block for ground) and second remote lead to small stud ( solenoid trigger) . Using jumper cables with starter off engine , negative cable clamped to starter mounting ear and positive jumper to large stud. Then use an insulated tool ( screwdriver) to connect across the large and small stud to crank . Do not keep these connections on for longer than necessary , overheating can result .
3. The test for solenoid trigger response performed correct and reading good ( even with bypassed NSS , good job ). Good readings , ign. Switch good . Happy with voltage reading
4. Not too worried about voltage drop on the positive yet , but thanks for the test . Once starter is working , let's try it once more . But a good test .
5. Yes , the trigger stud should be dead if key not held in crank , no short in solenoid . Battery voltage present at starter post and same on positive crimp connector at starter post . Some voltage drop but good . Probably normal but will check after jeep is running again with all connections made normally.
6. Happy with readings and starter circuit working correctly . Again , we will test for load later but readings aren't bad . Good job .
this is the reason I dismiss bench testing . At the store , I don't know what kind of load is placed on the starter in their bench test but if they can spin it , it can't be too much. Mounted on the engine , you are now fighting compression . That is load . This is where a bad starter fails.
Pone thing we have established at the parts store on their bench is that the solenoid works . This would mean to you that the starter motor itself is bad . Be it bad brushes , short in armature , etc. , it means that we need a new starter hung in place . Once working and proper clearance is confirmed between pinion and ring gear we can continue voltage drop tests .
Now if we can just keep the oil and coolant from killing a new starter , we will be fine !
Good job Sir James ! You the man ! Greg
