Trouble Starting - Ignition solenoid? 95 U300 CAT 3176

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Trouble Starting - Ignition solenoid? 95 U300 CAT 3176

November 08, 2021, 09:19:12 pm

So the coach was working fine the other day, started with no issues. I tried to start it today, no luck. First I got the clicking sound you normally get when you have a low battery. I threw the batteries on the charger to make sure they were full and then tried again. Same thing. Then I tried from the remote start in the engine compartment. I flipped the switch, buzzing started, oil pressure light on, then they slowly faded out, like as if they ran out of power. Now when I turn on the ignition key the dash doesn't even light up! I was thinking it was the ignition solenoid but now I am confused because it seems as though there is a different solenoid for the remote start in the engine bay? The chances of both going out is very low so I am thinking its something else?

Any Ideas?

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

Reply #1 – November 08, 2021, 09:39:26 pm

It sounds like dead battery or a bad connection. Did you charge the right battery or
set of batteries.

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

Reply #2 – November 08, 2021, 09:41:22 pm

What voltage do you get when you put a volt meter right to the start batteries?

Start there and report back

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

Reply #3 – November 08, 2021, 10:01:50 pm

The batteries are all good full 13.14v on them. Yes right set, not the house batteries

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

Reply #4 – November 08, 2021, 10:20:54 pm

Try activating the BOOST switch - see if that makes any difference when you try to start.

The starting sequence for my coach requires the following items listed below to function properly. I don't know if your coach works the same way. On my coach, if any one of the items listed below were to fail, I would have a NO-CRANK situation. This would be true even if all my batteries were fully charged.

1. Ignition switch

2. Ignition solenoid. Located under the lift-up dash cover.

3. Neutral safety switch (or relay). Sorry - I don't know where this item is located.

4. Aux Start Solenoid. Mounted on the isolator panel.

5. Starter Solenoid (mounted on the starter)

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

Reply #5 – November 08, 2021, 10:35:38 pm

Boost switch doesn't do much, just makes it make different noises.

Im going to check those other things out now.

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

Reply #6 – November 08, 2021, 10:42:37 pm

Link below to a more detailed description of the items needed for a successful engine start:

Starting trouble. Solenoid? Isolator? Something else?

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

Reply #7 – November 08, 2021, 10:43:28 pm

Quote from: oldguy – November 08, 2021, 09:39:26 pm

It sounds like dead battery or a bad connection.

If the batteries are good check the cables and grounds. To see the indicator lights dim to out still sounds like batteries. What was the battery state with the load applied?
Scott

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

Reply #8 – November 08, 2021, 11:03:26 pm

Pull the terminals off the posts and clean both until they are spotless. Always the first place to start troubleshooting.

There also may be a second solenoid for starting. Good to check that after above.

Pierce

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

Reply #9 – November 08, 2021, 11:12:36 pm

Batteries are literally brand new. Had them in the coach for about a month. I disconnect the ground when I leave it so there is no charge being pulled from them while it sits (I just found out that the boost can keep them charged while plugged into shore power). I know that seems like a battery thing but I am 99% sure it is not a battery issue. Im thinking it's a bad ignition solenoid but I am not sure if that would cause the issue at the back starter panel.

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

Reply #10 – November 08, 2021, 11:25:08 pm

If the boost changes the noise, check the cables on the starter and even
the wire going to the solenoid and then keep checking all the way to the
batteries. With a voltmeter go from negative to positive and turn over the
engine. If you have a big voltage drop, it's the batteries. If there is no voltage
drop move you positive lead along the cable until you find the voltage drop
until you get to the solenoid and if no drop do the same with the negative
lead along the ground path. If you still have over 12 volts the problem is
either the solenoid or the starter.

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

Reply #11 – November 08, 2021, 11:31:09 pm

Im going to check out the wires for any issues but the engine does not even crank so no turning it over at this point. No dash lights, barely any clicking other than one single click from solenoid when key is turned to on position.

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

Reply #12 – November 09, 2021, 09:20:01 am

Quote from: GeoKM – November 08, 2021, 11:31:09 pm

...the engine does not even crank so no turning it over at this point.

Back in the day, the old school solution to "No Crank" was to jump across the two large posts on the starter solenoid with a big screw driver blade.

If the engine turns over (tries to start) then you know your start batteries, cables, and starter motor are good (starter solenoid may be bad). The problem, in that case, lies elsewhere. Just sayin'

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

Reply #13 – November 09, 2021, 09:52:11 am

The reason I'm thinking (and hoping) that it is the ignition solenoid is that there is 12v power coming to the dash but when I turn the key on nothing lights up (it did 5 days ago when I ran it). I read somewhere that the ignition solenoid also powers the dash lights and shift panel, since those no longer light up I am thinking the coincidence is worth exploring the solenoid. I bought a new chepo unit off amazon supposedly a replacement for the part number listed on the site. I know it might not last long but I really just wanted to make sure it was the solenoid before I decided to never have this problem again and go buy the Blue Sea 9012.

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

Reply #14 – November 09, 2021, 10:19:53 am

Quote from: GeoKM – November 09, 2021, 09:52:11 am

I really just wanted to make sure it was the solenoid before I decided to never have this problem again and go buy the Blue Sea 9012.

The link in Reply #6 (above) provided a simple way to verify the function of the Ignition Solenoid. I will repeat it below so you don't have to go to all the trouble of reading my prior post.

4. Ignition solenoid: Located under your lift-up dash cover. Check with multimeter. With ignition key OFF one large post on the ignition solenoid should be HOT, and the other large post should not be HOT. Turn the ignition key to ON and both large posts on the ignition solenoid should be HOT. If not, [either the solenoid is bad, or] the small wire running from the ignition switch to the small post on the ignition solenoid may be broken or loosely connected.

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

Reply #15 – November 09, 2021, 10:54:38 am

Chuck,

So did the test, got weird results.
With key off HOT on battery side (measured 13.06v), not HOT starter side.
With key on HOT on battery side (ONLY 5.5V?), not HOT starter side.

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

Reply #16 – November 09, 2021, 10:57:16 am

Quote from: GeoKM – November 09, 2021, 10:54:38 am

With key on HOT on battery side (ONLY 5.5V?), not HOT starter side.

HMMmmm..... That is unexpected, for sure. I gotta think about that for a bit...

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

Reply #17 – November 09, 2021, 11:00:00 am

Since you already have another solenoid in hand, you might go ahead and swap them out. See if that helps the situation.

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

Reply #18 – November 09, 2021, 11:03:45 am

The solenoid should be here today so as soon as I get it im going to install and check it. The voltage drop has me super confused, could a faulty solenoid even do that?

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

Reply #19 – November 09, 2021, 11:10:39 am

The test result you describe sounds like what would happen if activating the solenoid connected your start battery bank directly to ground ...as in a dead short. Shorting out the battery bank to ground would certainly pull the voltage reading way down. However, it would also cause a BIG spark somewhere.

I don't see how this could really happen without seeing any voltage reading on the "starter" side of the solenoid where all the downstream circuits are connected.

I don't know...very puzzling.

Unless...perhaps the ignition solenoid itself was shorting directly to ground.

Does your old solenoid have 3 posts or 4 posts? If it has only 3 posts (2 big posts and one small post) what is the solenoid mounted on - a wood (non-conductive) surface or a metal (conductive) surface?

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

Reply #20 – November 09, 2021, 11:15:50 am

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 – November 09, 2021, 11:22:54 am

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 – November 09, 2021, 11:25:37 am

I have a 4 terminal unit

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

Reply #23 – November 09, 2021, 11:28:03 am

Quote from: wolfe10 – November 09, 2021, 11:22:54 am

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 – November 09, 2021, 11:39:08 am

Quote from: GeoKM – November 09, 2021, 11:28:03 am

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.

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