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Topic: Starting trouble. Solenoid? Isolator? Something else? (Read 1990 times) previous topic - next topic

Re: Starting trouble. Solenoid? Isolator? Something else?

Reply #25 –
Chucks suggestion with 2 volts meters you should do. For now if you put you
head lights on and then try and start it. If the head lights stay on the battery is
OK unless you have LED head lights. When a started won't work I always go to
the started and jump the solenoid if it doesn't work then I know it is the solenoid,
starter, cables or battery and if it starts I have time to look at the other components.
Peter and Frieda Morin
1999 36ft. U320 Foretravel
Build # 5436
1998 Suzuki Sidekick Sport

Re: Starting trouble. Solenoid? Isolator? Something else?

Reply #26 –
Quote from: Chuck & Jeannie –
Been mulling over your intermittent starting problem.  I'm not worrying about the other problems you mentioned - just working in my head on the "no crank" situation.  If I made any glaring mistakes in my sequence below, I expect the smarter members of this Forum to please correct me.

Here is a simplified list of the engine cranking sequence components in roughly the order that they are required or activated:

1.  Start batteries
2.  Ignition switch
3.  90 Amp circuit breaker
4.  Ignition solenoid
5.  Neutral start safety switch
6.  Aux start solenoid
7.  Starter solenoid
8.  Battery cables going to starter
9.  Starter motor

ALL of these components must operate correctly to make the engine crank.  There is other stuff required to make the engine start, but that's not our concern at the moment.  Loose, dirty or badly corroded wiring connections at any point in this sequence could cause intermittent failure to crank.

Expanding a bit on each component:

1.  Start batteries:  Batteries must be fully charged, with no dead cells.  Check each battery individually for proper resting voltage, 12.6 to 12.8, with a multimeter, and for dead cells with a load tester.  After batteries are tested, reinstall and be sure all cables and connectors are clean and tight.

2.  Ignition switch:  Check that the connections on the back of the ignition switch are clean and tight.  Make sure the "HOT" supply wire to the switch is good.

3.  90 Amp circuit breaker:  Located behind the white fiberglass cover on the aft wall of the central storage bay.  Supplies 12 volt power from start batteries to the ignition solenoid under dash.  Check to be sure it is HOT on both posts of the breaker.

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, the small wire running from the ignition switch to the small post on the ignition solenoid may be broken or loosely connected.

5.  Neutral start safety switch:  To tell the truth, I don't know where this switch is located.  If it does not work properly, the engine will not crank because it won't "know" the transmission is in neutral.

6.  Aux start solenoid:  Located on the isolator panel, or nearby.  With the ignition key in the OFF (or ON) position, one large post on the aux start solenoid should be HOT, and the other large post should not be HOT.  When the ignition key is turned to START this solenoid receives power to the small post from the Neutral start switch, and both large posts should then be HOT.

7.  Starter solenoid:  Mounted on the starter motor.  Receives activation power from the aux start solenoid.  When activated this solenoid connects high amperage feed from start battery cable to starter motor, and engages the pinion gear on the nose of the starter with the ring gear on the engine.  If this solenoid "sticks" it can sometimes be freed up with percussive persuasion.  See threads linked below.

8.  Starter motor:  Cranks the engine over so hopefully it starts.

Threads below may be of some help (or at least encouragement, knowing others have been in the same boat):

8.2 DD won't start

Its Aliiiiiiiiivvveee!!!!!!!!!!!!!!!!


  This is SOOOOO helpful Chuck!  Thank you!  Having a trail to chase down is super helpful.
-Trent and Siobhan Walker + 5 boys
Proud owners of a 1995 U300 SE that we bought from Jor.  We are so blessed and loving life on the road!

Re: Starting trouble. Solenoid? Isolator? Something else?

Reply #27 –
Start with cleaning all of the grounds.

Re: Starting trouble. Solenoid? Isolator? Something else?

Reply #28 –
When we got our coach we ran into a similar problem. Turned out that ours uses a cable that ties the three chassis batteries together (actually, two such cables, one for + and one for -), and they weren't making good contact with the battery posts. I bought new ones and haven't had as many problems. When I do, cleaning and tightening connections always seems to solve the problem.

I like the idea of those dual voltmeters. I may just have to get a pair.

Re: Starting trouble. Solenoid? Isolator? Something else?

Reply #29 –
Hello. Reviving an old thread here since it helped me find what i hope to be the source of my coach not starting. Long story short, I decided to replace the aux start solenoid after going through the list posted by Chuck & Jeannie. Thank you 1000X for this. I replaced the aux start solenoid with Cole Hersee 24213 12V 200A Continuous Solenoid, as i saw recommended on here. At the same time i thought the two circuit breaker fuses on the isolator panel looked really old and possibly bad. So, i decided to replace them, but ended up only replacing the one that is labeled 15A in the wiring diagram. It has three wires to it. One E59 WH to one of the relays, B35 WH to the aux start solenoid, and B33 WH to the other relay. I was unable to get a 15A in the auto parts store, so I got a 20A. I put the aux solenoid and this in at the same time, and my coach fired up. I then ordered a 15A circuit breaker fuse to replace the 20A, since the wiring diagram calls for this, and when i put this in I had again no start. So, i swapped it again for the 20A and the coach fired right up. My question is, is there a problem using this 20A instead of 15? Why would this be needed? Is it to do with the new aux solenoid being slightly different from the one I removed?

Thanks

Re: Starting trouble. Solenoid? Isolator? Something else?

Reply #30 –
B35 is bring power from the aux solenoid to the circuit breaker, B33 is the power out of the breaker to the A/C clutch relay. E59 goes to a battery voltage sensor input on the alternator. None of those should affect the starting circuit. When you turn the key, power goes to the neutral safety relay, If the relay is energized because the transmission controller says it's in neutral and provide power to the coil on the relay, power passes through that relay into the aux solenoid and engages the starter solenoid. The other breaker on the board is for the A/C condenser fan. 15A vs 20A shouldn't matter and shouldn't affect the start circuit. Where did you connect the two small terminals on the front of the new aux solenoid? One should be E9 wire, and the other one should be connected to a ground location. The coil in that is pulling less than an amp, so the circuit should have no issues powering it.
1991 U300 Side Aisle 6V92 Silver #3897
2004 U320 40' #6246