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Author Topic: Bus starting problem  (Read 2941 times)
jjrbus
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« Reply #15 on: August 06, 2008, 06:31:20 PM »

All the offers of help!!! I am very grateful. Wonderful community we have. I will try to muddle my way through it, I have a few weeks.

 As i sort through all the info and suggestions, it dawned on me that I am having two differnt issues, maybe?  At the rest area I was useing the bus and house batteries, the engin turned over but did not start. When the selonoid acted up I was useing the rear start and only the bus batteries. In the world of diagnostics I am comparing apples to oranges.

 I recently replaced the start bateries. The old ones were 7 years old without a problem. The new ones I am not happy with. I have taken them back twice, but they pass a load test. The old ones would hold a charge for a long time, these need a trickle charger on them or within 2 to 3 weeks are weak.

 On the bright side, I asked around today and found a real starter shop, they test, diagnose and rebuild.   Auto electric rebuilders corp.  623 Pondella rd. N Ft Myers FL  239  995 6334     With the advent of throw away, these places are getting harder to find!!

          Thanks for all   Jim
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JackConrad
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« Reply #16 on: August 07, 2008, 05:35:53 AM »

Jack,
I don't completely agree with you because sometimes the start relay will not pass enough voltage/amps to the solenoid to either engage it or hold it because of burned/corroded connections or termianls or just a weak coil.
This relay is very often the cause of starting problems. If it doesn't work properly nothing else to the starter will either.
A spinning starter means the solenoid is either not engaging the starter motor gear to the flywheel or is not holding it there.
It could be anything between the relay and the starter solenoid. It could even be the starter switch at the panell.  Jumping the relay will quickly show if the relay or switch is the problem. There was a string just recently in which the starter switch failed. As I remember all the starter switch does is ground the start relay.

Gus,
   Thanks for the information, I did not know a relay could suffer a "partial failure". Every relay failure I have experienced was a total failure. At least my relay failures were easy to diagnose LOL  Jack
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« Reply #17 on: August 08, 2008, 04:23:44 PM »

Jack,

The relay coils didn't always fail it was most often corrosion on either primary or secondary connections. Since these relays don't use much current it doesn't take much resistance to put them out of operation. I replaced a couple of them with modern type relays because they were so old.

As I remember once it was also the start switch, mostly old age.

A lot of the wires going into the inst panel and electrical panel connectors on my 4104 were corroded. I have been replacing the connectors gradually as I work on different elec components.
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« Reply #18 on: August 09, 2008, 02:20:31 PM »

Jerry,

I really liked your write up. Smiley  Not many auto electric trouble shooters measure the "drop" across each component.  I get similar info by measuring the V at the first part of the load.  That should be the bat voltage minus the drop across the fuse or ampmeter shunt.  I take that voltage as a ref and then I work down the line, with only the + terminals to find the voltage drop to that point.  I have TS a lot of auto systems and I have never seen erratic voltages EXCEPT if the bat load was causing the voltage to drop low enuf to allow the starter to drop out.  This caused voltage fluctuations "everywhere", including at the bat terminals.  I guess it is how much it drops or fluctuates.   Sooooooo, if I have a fully charged bat and the term voltage is 25V.....and I hit the starter switch.....how many volts is permissible at the starter?  Another way, how many volts can I "legally" drop across the contacts?  I have seen the full bat voltage at the starter + term and the thing still turned over to slowly to start.  Only once did I see this and it was the starter and all the rest it was a bad ground cable "to" the starter, as I recall and I didn't know I would be facing a self quiz. Cheesy

Again, I think your write up was great and to address all the possibilities would be a LARGE book and outside our scope.

Thanks,

John
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jjrbus
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« Reply #19 on: August 09, 2008, 04:25:15 PM »

That Jerry sure is a pro, not much gets by him.  I'm at the same park in N Ft Myers if you want to run down Jerry. 
 The rain and a roof leak have kept me off the starter project plus I have been looking for a analog volt meter. Maybe tomorrow?   Jim
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« Reply #20 on: August 09, 2008, 08:45:52 PM »

Thank you…JohnEd.
Sorry….perhaps I have not made my self clear on this subject. I am not a shop manual writer and not good in grammar but trying my best to get a step by step diagnostic in writing…while I am too far from being there to solve the problem.

You’re not the only one are confuse about my diagnostic check step from my earlier post.  And…I still see more posts after my reply, which they are suggesting whatever it could be. My profession has been diagnostic work in electrical, plumbing, old internal combustion engine (ICE), transmission, front wheel alignment, with/without posi-track rear end, air & hydraulic brake system. Most of it was my everyday job making a living since 1953 to 1970. I am not updated now since computer equips cars & trucks came out and am not perfect by all means.

What I am saying that most diagnostic can be done in must quicker time and replace only the problem’s part or parts or repair. Just follow the diagnostic steps.

Need to clarify this diagnostic step by step check points via using analog voltage meter to pin point problems….It is not all about resistant load in electrical system. Read on!
The following tests is using an analog volt meter is not to measure voltage but to see what the contact’s points condition are or wiring connections are like, by watching the needle movement for either erratically or steady while under load or cranking.

About erratic voltage meter reading…dirty or worn relay contact points from either the starter solenoid relay (before solenoid) or solenoid’s high current contact point (heavy duty relay). In other words, a partial contact or arcing points will cause a guarantee voltage meter to read erratically. If it good contacts…it will read a steady and low resistant voltage of less then .5 volt as per manufacture spec. (in general terms).

About measuring voltage….digital volt meter is much more accurate then analog version but cannot tell if how much of how high or big it is erratically if any.

On the other hand, you can use a cheap portable AM radio at about 1300 hertz with no station tune in. Hold radio near by starter or relay or whatever needs to check for arcing points/contacts or loose connection. It will sound cracking or scratching if it arcing or moving a loosen connection.
You can use AM radio to locate loaded or switch “ON” AC wiring in wall via listing for the humming “60 cycle sine wave” sound.

Also you can tell if you have shorted or open alternator’s diode by listening for high whining sound. Bad diode will sound growling and very hot alternator.

My hearing aid set on “telephone” mode will do the same as AM radio…cracking sound.

FWIW to you.

Sojourn for Christ, Jerry
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« Reply #21 on: August 10, 2008, 12:53:25 AM »

Spinning Jim:

Please if you will reopen my earlier "step by step" diagnostic post.

It all been modified to explain more clearly with a attach wiring map and labels.

Remember all testing results are done with cranking speed and fully charge battery.

Take care and say Hi to Josephine

Jerry & Lynette

PS...thanks for your support. LOL
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jjrbus
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« Reply #22 on: August 10, 2008, 09:22:06 AM »

Thanks Jerry, I hope they add your post to the wiki archives. I have moved it around the computer and managed to print it. I am also greatful for all others input an offers of help as well. After some searching I have obtained a analog meter, Home Depot was the only place I could find one. When it is dry I will attempt to muddle through this and post the results.  Spinning Jim
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« Reply #23 on: August 10, 2008, 12:02:04 PM »

Jerry,

I hope you understood that I was agreeing with you.  My alternate method of finding the voltage drop across a device by taking measuring the voltage at input and output (+ and -) and taking the difference is just that, another way to do the same thing as you did.

You evidently have a lot of experience in an assortment of automotive associated specialities.  I think that makes a better trouble shooter than a singular discipline trouble shooter.  I started out as a RADAR tech. in the AF.  Radar is unique as a field as it contains hydraulics for antenna drive and control, diesel powered AC generators,  Aplidine generators, mechanical drivelines and devices, house ac power distribution, DC circuits and , of course, electronics up the yin yang.  I, as all others in my field, had to stay current and work on the systems that had the various specialties/skill requirements daily.  It kept your nose in the books.  For three and a half years I taught these subjects as a work center supervisor, OJT supervisor and in a formal classroom environment, at least as far as the equipment was contained in my Radars.  All of that military experience is sans computers.  I guess I was good at it as I promoted every man that worked for me, and to a man, they had "outstanding" fitness reviews that they well earned.  Every man reinlisted for 4 years and that from a base of 450 that saw not a single first term reenlistment in 4 years except from my men.

I have a friend that is the sole proprietor of "Always Jake" Auto Electric Repair.  I spend an hour a week sitting with Chris and talking about starters and generators and DC motors.  He is not only knowledgeable but generous with his 20 + years of experience and believe me when i say that I ask a lot of questions and do a lot of listening.  There is no substitute for experience and in his field he has seen it all or almost all.  All of my training and experience insures only that I fully understand everything that Chris says about DC devices.  Yep, it is my humility that I am most proud of in my many virtues. Roll Eyes

Like you I guess that I am  a "jack of all trades" in some regards.  Even with 4 degrees i don't think I have mastered any of the ones I had.  Based on results I was good at them, though.  And you seem to share that experience and skill, and most importantly, willingness to share.  And like Van, I enjoy and profit from your company. Smiley

If you want to track down the source of "noise" on a DC line or detect a missing leg on a rectifier you can switch the analog Multi Meter to the AC scale.  Noise and excessive ripple register as AC voltage.  For those of us that don't have "hearing aids" to give us the edge in DC circuit analysis Grin Grin Grin Embarrassed

Hope this is clear,

John

PS: what is the significance of "to you" in you sign-off?
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"An uneducated vote is a treasonous act more damaging than any treachery of the battlefield.
The price of apathy towards public affairs is to be ruled by evil men." Plato
“We can easily forgive a child who is afraid of the dark; the real tragedy of life is when men are afraid of the light.”
—Pla
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