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Topic: Trouble Starting - Ignition solenoid? 95 U300 CAT 3176 (Read 1597 times) previous topic - next topic

Re: Trouble Starting - Ignition solenoid? 95 U300 CAT 3176

Reply #20 –
Chuck,

I tried something else maybe this will help the diagnostic.

Same test but this time with the boost switch turned on, results below

Key turned off - Battery side HOT (13v), Starter side not HOT
Key turned on - Battery side HOT (13v), Starter side HOT (13v)

Tired to start it, heard a click and all lights flashed but no start, acted like a dead battery...... is there a chance that the batteries are bad? I mean how could 3 new batteries go bad like that? They are all fully charged, showing 13V.

Re: Trouble Starting - Ignition solenoid? 95 U300 CAT 3176

Reply #21 –
Doesn't sound like the ignition solenoid.  EASY test.  Verify that the dash HVAC fan works with ignition on.  No need for a voltmeter.

And with voltage dropping that much, almost has to be a bad connection if voltage at the chassis battery doesn't drop with ignition on.

Re: Trouble Starting - Ignition solenoid? 95 U300 CAT 3176

Reply #22 –
I have a 4 terminal unit

Re: Trouble Starting - Ignition solenoid? 95 U300 CAT 3176

Reply #23 –
Quote from: wolfe10 –
Doesn't sound like the ignition solenoid.  EASY test.  Verify that the dash HVAC fan works with ignition on.  No need for a voltmeter.

And with voltage dropping that much, almost has to be a bad connection if voltage at the chassis battery doesn't drop with ignition on.
Nothing comes on when key is turned to on position. No lights, no HVAC.

Im checking the voltage at batteries with key on now. EDIT: No change in voltage at chassis batteries when key is turned on. 13.06v key off, 13.06v key on

Re: Trouble Starting - Ignition solenoid? 95 U300 CAT 3176

Reply #24 –
Quote from: GeoKM –

 No change in voltage at chassis batteries when key is turned on. 13.06v key off, 13.06v key on

Then you DO have a bad connection or bad cable.  Check cables at the battery end carefully.  Green (oxidized copper) does not conduct electricity.

Re: Trouble Starting - Ignition solenoid? 95 U300 CAT 3176

Reply #25 –
I'm stumped...but I graduated with an English degree (5 decades ago) so I have a excuse.  Hopefully some smarter member will come up with a bright idea to help you further test (isolate) the problem.

Re: Trouble Starting - Ignition solenoid? 95 U300 CAT 3176

Reply #26 –
Quote from: wolfe10 –
Then you DO have a bad connection or bad cable.  Check cables at the battery end carefully.  Green (oxidized copper) does not conduct electricity.

I am going to get the safety blocks out and crawl under there to check things out. Could this possibly be an issue with the ignition switch/tumbler itself? I know my father installed a new ignition as the one that was on it was the wrong one or something. He replaced it with the correct Chevy one that is shown in the wiring diagrams that came with the coach. 

I am still a bit confused as to why the boost switch makes it so there is a full voltage at the solenoid? Would that indicate something like a particular wire to check? Are there different wires that run from the chassis batteries to the ignition then solenoid than the ones that run from the house batteries? Just trying to figure out why I don't see a voltage drop with the boost switch on, if they shared a wire to the ignition then the solenoid wouldn't it act the same in both situations?

Re: Trouble Starting - Ignition solenoid? 95 U300 CAT 3176

Reply #27 –
Chuck showed how to bypass everything to start the engine in reply 12. Have you
tried that. Those two pictures will tell you a lot.

Re: Trouble Starting - Ignition solenoid? 95 U300 CAT 3176

Reply #28 –
Quote from: GeoKM –
Could this possibly be an issue with the ignition switch/tumbler itself?
All the ignition switch does is supply the activating voltage (when you turn the key "ON") to the small positive terminal on the ignition solenoid.  One small terminal is positive (activation) and one is negative (ground).  The small posts are interchangeable - doesn't matter which is which.

Re: Trouble Starting - Ignition solenoid? 95 U300 CAT 3176

Reply #29 –
If the ignition switch is suspect, EASY to check.

Just use a small gauge jumper (not carrying much amps) between the battery lug side of the ignition solenoid and the positive small terminal on the solenoid that comes from the ignition switch.  I would remove the wire from that small terminal so you aren't backfeeding anything.

Re: Trouble Starting - Ignition solenoid? 95 U300 CAT 3176

Reply #30 –
I don't believe it is the ignition switch as you said it tried to start on boost. It won't
start on boost batteries alone.

Re: Trouble Starting - Ignition solenoid? 95 U300 CAT 3176

Reply #31 –
While you are under there checking, be sure to check the engine end of not only the positive, but also the negative/ground.

Re: Trouble Starting - Ignition solenoid? 95 U300 CAT 3176

Reply #32 –
Quote from: GeoKM –
1.  I am still a bit confused as to why the boost switch makes it so there is a full voltage at the solenoid?

2.  Just trying to figure out why I don't see a voltage drop with the boost switch on, if they shared a wire to the ignition then the solenoid wouldn't it act the same in both situations?
All the boost switch does is physically connect the two battery banks together.  It merely increases the number of batteries in the "Start" battery bank.  All of the current required for starting the coach still flows through the exact same circuits, regardless of how many batteries there are in the "Start" battery bank.

So yes, IMO your ignition solenoid test should yield the same result with boost switch on and off.  The results you report don't make logical sense (to me).

Re: Trouble Starting - Ignition solenoid? 95 U300 CAT 3176

Reply #33 –
Im checking things out now, testing the ignition as Wolfe suggested. One thing I just noticed was the Overload was flashing on the Heart Inverter Panel above the door? I disconnected the shore power for a minute and then plugged back in. No more blinking.... not sure if that has something to do with this but seems connected?

Re: Trouble Starting - Ignition solenoid? 95 U300 CAT 3176

Reply #34 –
Wolfe i did your text by jumping the battery side to the smaller solenoid pole.

Voltage measured at 13v on battery side, I jump to the small pole and it drops to 7v, solenoid does not click, just kinda soft buzz from it

Re: Trouble Starting - Ignition solenoid? 95 U300 CAT 3176

Reply #35 –
Ya, 7 VDC will likely not activate the solenoid.

And if that 7 VDC reading was on the chassis battery lug of the isolator, it still says that even a small draw is dropping the voltage significantly.

Because voltage at the chassis battery is not dropping, that suggests "pathways" between batteries and solenoid and back through the ground circuit.

Re: Trouble Starting - Ignition solenoid? 95 U300 CAT 3176

Reply #36 –
Okay little update. I unbolted and cleaned the main engine to frame ground connections. This included the cable from the engine to the starter. Ran my test again now I am seeing the voltage drop to 10v instead of 7v. I think im on the right track here. Now all I have to do is find all the connections I need to clean..... I am going to do both positive and negative throughout. Any idea how many connections/cables I am looking at having to sand and reconnect?

EDIT: So now the solenoid clicks a couple times but then the voltage on battery terminal drops to 3.3v......

Re: Trouble Starting - Ignition solenoid? 95 U300 CAT 3176

Reply #38 –
Okay so I have been waiting for a friend to come over to help with the wire inspection, in the meantime, I did a little more testing and found something odd, maybe enlightening.

If I disconnect the batteries and then reconnect them, then go inside and turn the ignition to the on position everything powers up as it should. When i try to start solenoid clicks over and you get the typical dead battery situation.

Heres where its odd, if I turn the key off and then try to turn it back on, 1 small click from the solenoid and no lights on the dash.

If I then go and disconnect and reconnect the batteries again and then turn the ignition from off to on, lights on the dash and everything comes on and the process restarts. To me this is odd.

Re: Trouble Starting - Ignition solenoid? 95 U300 CAT 3176

Reply #39 –
That is not odd at all it is an indication of a bad connection.