Help trouble shooting short to starter solenoid

I’ve been tricked many times now into thinking this was a dead battery, alternator etc, but now I’m certain the issue lies with the wiring to the starter solenoid.

Just left the dealer for the T21 recall (seemingly successfully), drove about 1 hour, stopping and restarting a few times. The last attempt gave me the dreaded click.

A multimeter on the starter solenoid has me zeroing in on this wire. With the key off, the solenoid post is reading 12.7 volts, same as battery. When the key is turned, it drops down to 3v. No wonder it won’t engage.

I’m going to start by removing the solenoid wire and testing it. I assume the short is somewhere in the harness. Any guidance is appreciated.

SkyGypsy said:

I’ve been tricked many times now into thinking this was a dead battery, alternator etc, but now I’m certain the issue lies with the wiring to the starter solenoid.

Just left the dealer for the T21 recall (seemingly successfully), drove about 1 hour, stopping and restarting a few times. The last attempt gave me the dreaded click.

A multimeter on the starter solenoid has me zeroing in on this wire. With the key off, the solenoid post is reading 12.7 volts, same as battery. When the key is turned, it drops down to 3v. No wonder it won’t engage.

I’m going to start by removing the solenoid wire and testing it. I assume the short is somewhere in the harness. Any guidance is appreciated.

Click to expand...

What is the battery voltage when the solenoid post is 3v? If the battery voltage follows, it's the battery.

Regards,

Mark

I believe that the power to the starter solenoid coil is fused.

Assuming a good battery.

If the solenoid clacks in, the starter doesn't turn, and the system voltage drops to 3 volts then maybe the starter has a bad "spot" or bad coil in the starter motor. At 3 volts my bet would be more toward a wonky ground or other bad connection somewhere in the heavy cable section of the system.

That said, it could be other things.

vic

The battery is brand new. I haven’t measured the battery during the “no start click” event this time around but in the past I was reading about 11v during cranking at the battery and 10v at the starter. This is after I got it to start (incidentally by bumping the solenoid lug and big cable starter lug to short and provide the full battery voltage).

I just acquired some tools, and removed the solenoid cable. The lug at the solenoid is showing 12.7 volts, same as battery. Shouldn’t this be 0v when the solenoid is not energized? I’m also getting a reading of about 5v from the cable eyelet.

I’m confused.

Okay. Just ran another test. Removed the relay under the seat and ran a wire from the hot pin to the battery to manually energize the starter solenoid. With the cable eyelet connected, I’m getting a drop from 12.7 to around 3v. With the eyelet disconnected the eyelet is reading anywhere from 0-7v, but not unless the probe is really held well against the eyelet (I have alligator clips for my dmm also.)

When the eyelet is showing voltage and the solenoid is energized, the voltage drops down to 0v then comes back up when deernergized.

added (1st part, see below): By the 7v symptom, i think your starter may have an open coil or a dead spot on the commutator (what the brushes ride on), or simply worn brushes.
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The solenoid is also a relay.
When it's energized (by the little wire from the seat-side starter relay), it closes a very beefy relay internally.

Here's the circuit diagram ... if the starter has a bad (shorted) coil, the current draw can be very high, dragging the battery down. see added
You really do want to see what's happening at the battery when the solenoid is only showing 3v.
The two coils shown inside the "starter motor" box are really in the solenoid. Note how each one goes to a different end of the actual motor.



I'm fairly sure the red notes were added by Vic/AquaPuttana

added: looking at the figure, when the solenoid is actuated, the little wire terminal *will* try to be at 6v or a bit above, since its two coils are bridging 12 volts ... so that's a diagnostic that the MOTOR itself is really an *open* circuit (and open coil).
So now i'm voting for "solenoid working, starter motor has open coil" (or bad commutator segment or brushes).



--dick

Click-No-Start problem, Solved?

Aha!

I'm certain I found the problem.

Troubleshooting:

First off, I was measuring the solenoid voltage incorrectly. When I had the terminal disconnected I first had the DMM connected to the battery positive then to the ring terminal eyelet for the solenoid. I believe the voltage drop I was seeing was because the wire was first showing the voltage from the positive, then it was showing the measurement in parallel to the wire being energized. It was confusing until I switched connections and put the multimeter between the small terminal on the wire and the ground. Then the measurements became more predictable, showing the reverse of what I was seeing. Essentially, when the hot wire from the relay pin was touched to the battery positive, the meter rose to 12.7 volts.

Next came the interesting part. I tried to bridge the starter solenoid with the larger terminal from the big battery cable on the starter. To my surprise nothing happened, not even a click. I started testing the big lug with my DMM. I noticed that the bare end of the cable was exposed and looking fairly green, I used my multimeter test lead to scrape around and clear some corrosion off.

Once connecting the alligator clip to ground and the other clip to the big starter lug, my DMM read 12.6v, the now current battery voltage. I hot wired the solenoid again. To my surprise the voltage dropped from 12.6 to 0.5v. Crazy.

Getting it to Start:

I put some electrical tape across the solenoid terminal, then got out my jumper cables. I put one side on the larger starter lug and the other on the battery then made sure the connections were secure. I then used the hot wire to trip the solenoid, and my engine turned over.

I think the cable connection at the starter is in need of repair. After the engine turned over, I was able to start it with the key again. I think the engine moving during start up made the connection better. Also, I'm speculating that the cable has arced itself to the large lug terminal piece for the starter. This problem has been plaguing me and once I get it to start it doesn't happen again for a couple weeks or months. Maybe the arc weld is reconnecting then breaking again.

Anyway, maybe tomorrow I'm going to redo the connection at that terminal. Has anyone ever done this? I wonder how many other click-no-start events are rooted at this cause.

IMO change the starter. I’ve been there before with starters, they fail a few times here and there, then one day.....nothing. I had a manual car where is it wouldn’t hit, I could rock the starter by pushing the car in gear..then it would hit...eventually that didn’t work either. The cost of a tow greatly increases the expense of a new starter.

I’m going to agree with POM, at least pull the starter and have it bench tested. Dead spots in motors quickly turn into dead motors

BrennWagon said:

I’m going to agree with POM,
...

Click to expand...

+1

BrennWagon said:

at least pull the starter and have it bench tested. Dead spots in motors quickly turn into dead motors

Click to expand...

If you disassemble the green connection in question and find the corrosion to be 100%, then MAYBE that connection is your problem. Otherwise, I believe replacing the starter is a worthwhile investment.

Given the years and miles on most any T1N a bad starter wouldn't be a surprise. You can always pull the starter and take it to a shop or auto supply house for testing as suggested. We have a local auto electric shop that rebuilds starters and alternators. I have used them many times for boat engine starters. Those businesses are getting more scarce, but a good shop may have quick turn around time.

Doktor A warns that you should stay with OEM brand. Some aftermarket starters have dimension issues which can cause problems. Bosch is a common OEM brand. Valeo may be another possibility.

vic

I've had the starter bench tested in the past while experiencing one of these no start events. It tested fine. Brought it back, put it back on and still no start.

Think about it, bridging the large cable terminal end to the small cable would not even engage the solenoid. There must have been a lack of flow through that large terminal.

I am going to start off with checking the cable end and go from there.

SkyGypsy said:

I've had the starter bench tested in the past while experiencing one of these no start events. It tested fine. ...

Click to expand...

Bench testing isn't always 100%. For one example there can be odd brush assembly/commutator segment issues which are intermittent. The solenoid contacts could have contact surface problems, but that only applies if the solenoid is clacking in. Does the solenoid always "clack" in? It should be fairly loud without an engine turning.

Given the time that has gone by without resolution, and the age of any T1N OEM starter, replacing the starter/solenoid assembly can make sense. (Assuming the starter is OEM, if not OEM branded then replacing an off brand aftermarket starter can also make sense.)

But...
I've not even been close enough to look at your Sprinter from afar let alone do any testing.

vic

Here’s a few questions that I don’t believe have been answered yet.
1. Is your CEL illuminated?
2. Have you ever changed out your engine to chassis ground cable?
3. Did you have this issue before the T21 recall was performed?

A faulty or failing ground strap can intermittently allow enough power flow to allow proper operation and at others not provide enough power to turn the starter motor. The voltage drop that you reported could be consistent with that. The ground strap is less than $20 and a bit of a pain to replace, but may be the solution to your problem, although usually you’ll get a very slow crank from a bad ground, unless the battery to chassis strap is faulty too (less than $10)

Good luck

BrennWagon said:

Here’s a few questions that I don’t believe have been answered yet.
1. Is your CEL illuminated?
2. Have you ever changed out your engine to chassis ground cable?
3. Did you have this issue before the T21 recall was performed?

A faulty or failing ground strap can intermittently allow enough power flow to allow proper operation and at others not provide enough power to turn the starter motor. The voltage drop that you reported could be consistent with that. The ground strap is less than $20 and a bit of a pain to replace, but may be the solution to your problem, although usually you’ll get a very slow crank from a bad ground, unless the battery to chassis strap is faulty too (less than $10)

Good luck

Click to expand...

1. No

2. The battery to chassis has been replaced. I have a new ground strap ready to go on, but I haven't replaced it yet because last time I needed a impact gun to remove it. At that time I cleaned all the cable terminals and the chassis grounds with a dremel and sandpaper, they were mirror shined. I should put the new strap on. Haha, strap-on.

3. Yes


Personally, I think it's the starter cable, but I haven't had a chance to get a closer look yet.

Not that hard to run another heavy gage wire from battery to starter see if the problem goes away.

Patrick of M said:

Not that hard to run another heavy gage wire from battery to starter see if the problem goes away.

Click to expand...

True. I think that's what I'm going to do.