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HomeOff Topics › Car starter gurus input needed
04-19-2018 09:28 PM  60 days agoPost 1
Pistol Pete

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Seffner, FL

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I'm troubleshooting a car starter but have a shorting issue.

Problem...
Turn ignition key, starter cranks, engages, tries to turn engine but quits after a second or two.

Voltmeter across battery displays 12.6V and then drops to 8V under load and finally 0V, all within two seconds. Dashboard lights go out.

Immediately disconnect battery cables to avoid battery from being fried.

Battery is not the problem as it acts same with another known good battery. Initially I had suspected battery and attempted to jump start car. Then installed second battery directly with same results. Had car towed back home and here goes the rest. No prior dash light came on nor engine issues before. It just wouldnt start in driveway after normal use.

Attached an OBDII reader and NO CODE displayed. Arrrg!

Engine ground checks out as does battery negative cable and starter body when installed. Cleaned-polish all contacts and grounded terminals to assure a solid ground. Including engine grounding cable.

Starter "trigger" cable has 0V and then 12V when ignition key is turned ON and ignition relay checks out. All fuses good.

Did a voltage drop across all related cables and all is normal.

On bench, starter acts "normal" as it does when installed.

So...isolated motor and solenoid

Solenoid test...
OHM meter set at 200
Continuity test on coils checks out.
Iron core plunges when power is applied.
Iron core "springs" back to original position when power removed.
I get continuity on both battery input contact and output to motor contact (studs) when power applied. No power, no continuity.
Pushing iron core in by hand with no power also checks out with continuity test.
So far...all is good.

Motor test...
Turns when power applied.
Disassembled motor and removed armature.
Cleaned and polished for good contact. Used a brass brush and compressed air as well as some brake cleaner.
OHM meter set at 200.
NO continuity between commutator and shaft.
NO open circuit when testing windings at 180 phasing or by pairs. All ohm readings are equal.
So far, all still good.

Brushes...
All four are in good condition with at least 1/4 inch material left.
Two are grounded to starter base by means of attaching screws and continuity test confirms both are grounded to each other.
The other two are isolated from body and the two grounded to base brushes above. They are connected to each other by a braided wire that goes out of motor sleeve via a rubber isolator and connects to solenoid. Continuity test confirms they are both connected to each other.

Unless I missed something, everything sounds normal so far, right?

BUT, when I reinstall armature, the "isolated" brushes are now grounded as well. No clue is brake cleaner might have caused this or made it worst.

Unless not normal, then this is my short and armature test was erroneus.

Starter (OEM)
Toyota 28100-20020
Denso 428000-1840
2006 RAV4

Any input appreciated. I cannot find anything on the net about that in particular. Short of taking it to an alternator repair shop or getting a used one, whichever is cheaper. In either event, I figured to ask here 1st before a rav4 forum and their annoying generic forum ads.

I have yet to troubleshoot alternator but problem seems to point at starter...hands down.

Thanks!

~~Enjoying the hobby one flight at a time~~

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04-19-2018 09:45 PM  60 days agoPost 2
spaceman spiff

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Tucson

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Engine has locked up?

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04-19-2018 09:51 PM  60 days agoPost 3
ticedoff8

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Morgan Hill, CA. USA

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If the battery voltage is dropping to 0v within a few seconds of cranking, than there must be smoke coming from someplace - that is a dead short.
And, the battery cables would be red hot before you had a chance to remove the terminal

If the problem is in the starter motor, I would expect you to have seen arcing / scorch marks inside the can.

It may be the alternator's internal voltage regulator is fried.
But, I doubt that would cause the voltage measured across the battery terminals to drop to 0v.

Good luck.

Believe 1/2 of what you see and none of what you hear.
Fake News will be the downfall of our Republic!

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04-19-2018 09:52 PM  60 days agoPost 4
ticedoff8

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Morgan Hill, CA. USA

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spaceman spiff
Engine has locked up?
That is a great question.

Believe 1/2 of what you see and none of what you hear.
Fake News will be the downfall of our Republic!

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04-19-2018 09:55 PM  60 days agoPost 5
tadawson

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Lewisville, TX

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Definitely sounds like a short in the started. OP said the motor *does* crank, so lockup is not an option . . . Pretty much the only thing that can pull a battery down that fast is the starter and associated circuitry. Were it a cable fault, it would do that all the time, not just with the key . . . pretty much leaving the starter as the sole possibility . . . Hard to tell as well, not testing under load. Forces when applying torque may displace something and cause the short that you don't see with the starter loose on the bench. That much current, though, I would think you would see a pretty good size burn spot in the starter somewhere.

Friends don't let friends become electrotarded . . . .

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04-19-2018 09:56 PM  60 days agoPost 6
Pistol Pete

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Seffner, FL

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No. Engine is not seized and has oil. All fluids normal.

Engine did not stop working while on the road. It arrived at destination then just would not start.

Can turn engine by hand by means of serpentine belt until compression. Limited kung-fu grip

Can further turn full rotations by flywheel and a screwdriver.

No indication of mechanical damage which points to electrical.

Edited
Starter has a plastic "stationary gear" that will give in the event of a seized engine. This is to further avoid damage given starters high torque.

~~Enjoying the hobby one flight at a time~~

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04-19-2018 10:11 PM  60 days agoPost 7
dgoss999

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UK - Lancashire

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If this is petrol (gas) pull the plugs and let the engine crank off load.

Measure for any DC voltage drop across the connections to +ve and -ve ie.. between the +ve LEAD POST on the battery and the +ve wire to the starter. The -ve LEAD POST and the -ve lead to the chassis. Also measure the voltage between the engine block and the -ve post on battery.. All this while the engine is cranking!!

There should be minimal to zero volts DC across any of these 3 points.. Any significant potential across any of these 3 will indicate a poor connection. I know you said you did resistance test of these points, but a voltage drop across any of them under load will show a problem where Resistance testing doesn't.. The connection under load may be failing.

DG

"Believe none of what you hear, and only half of what you see." • Benjamin Franklin

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04-19-2018 11:39 PM  60 days agoPost 8
outhouse

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auburn ca

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Need a new starter

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04-20-2018 12:34 AM  60 days agoPost 9
Damper

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Point Blank TX USA

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How about that in line fuse going bad?

Full Throttle Spooning Leads To Forking

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04-20-2018 02:22 AM  60 days agoPost 10
RM3

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Killeen, Texas - USA

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had that scenario happen twice... your starter is fried. Although the bench test indicates that it does spin with power applied, it will not indicate that a few of the winding may now be shorted to each other, thus the motor doesnt have the torque to spin the engine, plus as the windings are shorted to each other, it draws alot of current when under a load, which is not indicated when testing without a load on the starter... simple answer: get a new one.

I know you stated you did an ohms test on the windings... but shorted windings will only vary the ohm reading by fraction of an ohm as copper wire has a resistance of 4 ohm per 1000 feet for 14ga wire... and Im more than positive you dont have anywhere near 1000 feet of wire per winding...

showing a preference will only get you into trouble, 90% of everything is crap...

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04-22-2018 02:55 AM  58 days agoPost 11
pctomlin

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Texas

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Agree with RM3s assessment, starter is toast. To ultimately prove it you need to find out how many amps the starter is pulling when you try to start the car. The RAV4 should pull no more than 150 amps IMO, typical range is 60 to 150 amps on most gasoline engines.

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04-22-2018 03:44 AM  58 days agoPost 12
InvertedDude

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USA

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Pistol Pete
1)Check starter by running a test

2)Check ACL relay (main relay that powers your entire car) Relay can work normally until energized, then drops your voltage to 0v as you described.

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04-22-2018 05:15 PM  58 days agoPost 13
Pistol Pete

rrProfessor

Seffner, FL

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Thanks for "troubleshooting" feedback.

While replacing is the easy solution, my goal was to troubleshoot to component level, sort of speaking, as I wanted a definite answer.

I couldn't do an amp load test when mounted test since it would short batt and disabled car.

However, I was able to load test starter on bench. Took some rigging but managed to recreate short.

I then bought a used working starter with one year warranty for only $32 and confirmed suspicion by swaping armature.

Since toyota uses the same starter across many models and years, they're not hard to find. The place I got it from displays many photos from the car it comes from. Mine came from a 2014 wrecked from behind car. I now have a spare solenoid as well which cost about $26 new. Win-win. Called in 1st and it was ready at counter for pick up.

http://gagelsautoparts.com

~~Enjoying the hobby one flight at a time~~

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04-23-2018 07:58 PM  57 days agoPost 14
AirWolfRC

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42½ N, 83½ W

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Something like this can measure your starting current without disconnecting any wires.

https://www.amazon.com/Auto-Ranging...L70_&dpSrc=srch

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04-23-2018 08:08 PM  57 days agoPost 15
Pistol Pete

rrProfessor

Seffner, FL

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Indeed a clamp on amp meter with max hold would have been great...last week.

~~Enjoying the hobby one flight at a time~~

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04-23-2018 08:37 PM  57 days agoPost 16
BeltFedBrowning

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Kansas City

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Here is what I have used at my mechanic job for the last 25 years.

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04-23-2018 09:32 PM  56 days agoPost 17
Machinehead01

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Lower Michigan

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Sounds like the engine ground
Check for corroded or even disintegrating(falling apart) ground lead.
Had my Subaru do the same thing. It was the engine to body ground lead.

"You judge according to the flesh; I am not judging anyone."

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04-24-2018 04:30 PM  56 days agoPost 18
tadawson

rrElite Veteran

Lewisville, TX

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AirWolfRC
Something like this can measure your starting current without disconnecting any wires.

https://www.amazon.com/Auto-Ranging...L70_&dpSrc=srch
The specs on that are very vague, and note that most clamp on ammeters cannot do DC current . . . it's a feature more typically reserved for higher end gear. They say "AC/DC voltage" but just "Current", so pretty hard to tell ....I'd be skeptical on that one, not only as an ammeter that can do DC, but period . . . that cheap typically means unsupported, unrepairable crap . . .

Friends don't let friends become electrotarded . . . .

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04-24-2018 04:50 PM  56 days agoPost 19
AirWolfRC

rrProfessor

42½ N, 83½ W

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Look closer . . . that one can measure DC current up to 400 amps.
You will have to pay a bit more to get peak measurements. I paid $40 for my version.
https://www.amazon.com/MS2108A-Rang...L70_&dpSrc=srch

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04-24-2018 05:22 PM  56 days agoPost 20
outhouse

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auburn ca

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Just replaced a starter that was intermittent and would drag when hot, solenoid was bad. On those Toyota starters, some have replaceable copper contacts on back of motor that make the actual connection, which if worn can fail under load but bench test fine.

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