Electrical problem... of my own making, I think

[David T. Richelderfer]

I replaced my two 12v chassis batteries with new Les Schwabbies. In the process of putting in the new batteries, YES I got them in backwards.  I didn't take a picture on my cellphone and didn't take notes as to the batteries and cables configuration.

Lesson #1: ALWAYS TAKE A PICTURE AND TAKE NOTES!

So I had everything just exactly backwards... red cables on negative terminals and black cables on positive terminals.  Guess what... no power to the key switch and a totally dead dashboard.  Now I'm pretty sure I have the batteries in correctly and the cables attached correctly.  Still no power to the key switch and dashboard.

I called the dealer where I bought the coach asking for help.  We found an ANL 200 amp fuse blown in the cabinet with the Big Boy and BIRD system above the coach batteries.  Interestingly, after several hours of sitting the power returned to the key switch and dashboard, but a dead starter when I try to start the C-12 engine.

I found and replaced the blown ANL 200 fuse ($10) with one I found at a local car stereo shop.  With the new ANL 200 fuse in place, I have power at the key switch and dashboard, but still nothing when I turn the key to start the C-12 engine.  So I continued looking around for anything that doesn't look right.

Lesson #2: High amperage fuses are often used in higher power sound systems... in cars and on stages.

In the basement electrical bay beneath the pilot's seat there is a solenoid.  I found a very small half-cylinder plastic piece that obviously came off a solenoid attachment, a "3A Standard rectifier" part name/number "1N5404 3A 3 Amp 400V Diodes Axial."  I am told the local O'Reilly's store is open.  Soooo...   I am now on the hunt for this small diode, but I may just buy a whole new solenoid.

Present situation:  I have flipped off the inverter at the 120v panel to reset it (hopefully).  I have the coach plugged into my home's 30 amp outlet with a/c running.  The hydraulic leveling works with the key on and I have leveled the coach with it.  The Kenwood screen/radio/dvd player does not have power, but the SilverLeaf screen does have power.  The dashboard has power; all the normal lights on the dashboard seem to be working when the key is on.  The inverter control panel inside the coach has power and appears to be functioning normally... but both the C-12 and generator starters will not actuate to start those engines.

What reset or fuse am I overlooking?  

[Edward Buker]

Neither starter would have been actuated so they are fine. The solenoid in the front should be fine, just the diode should need to be replaced. You can check that by turning the key on and checking the right copper buss is powered up and down with the key. When the high current fuse blew there was very high current shorting taking place and diodes like on the front solenoid are prime candidates for shorting out.

 I do not know if the ECUs for the engine, transmission, or the generator would tolerate the reverse polarity. Time will tell on that one.... Remove the diode completely from the front solenoid until you get a new one. Any 3amp diode with at least a 100V rating will do. In both the generator case and engine case when you switch either the key or the start switch to the generator there needs to be 12V applied to the small 12V starter solenoid lead. I would check there and see if you have 12V when held in the start position. The generator may have a delay built in for preheat before the starter has 12V applied to the solenoid. If you do not see 12V then I would work my way back on that wire with a schematic to what comes next. Hopefully it is a relay, fuse, or some easily replaced part.

Later Ed

[Steve Huber Co-Admin]

David,
The solenoid is OK if you were able to level. You can double check by seeing if the driving lights and wipers work as all 3 circuits are fed from the ignition bus that is powered when the solenoid is energized. I agree with Ed re the starter motors. Both should have independent solenoids but I don't know where they are located. Since neither work I suspect a common cause, relay of fuse.
A call to Ken at BCS might be in order. I'll take a look at the wiring diagrams on the BAC site to see if I can figure it out.
Steve

[Steve Huber Co-Admin]

David,
I strongly suspect that the problem(s) is due to a blown fuse on the fuse module. It should be located in the battery compartment. The module should contain 5 fuses, FH1-5 and a couple of modules. FH1 (15A) is Battery Power. FH2 (20A) is VIM power. FH3 (20A) is ECM power. FH4 (20A) is Ignition power. FH5 (30A) is Cooling Fan power. I think FH4 is most likely the problem for engine start, but check them all.
Steve

[David T. Richelderfer]

Here's the pertinent poop regarding the questions/information above.

With the key in the OFF position:
     1) In the electrical bay the right most copper buss is cold.  The other two left copper busses are hot.  The solenoid's left large post is hot.  The other three posts are cold.
              SOLENOID
            H               C               Capital letter means large post.   H/h=HOT
                  c     c                    Small letter means small post.     C/c=COLD

With the key in the ON position:
     1) In the electrical bay all three copper busses are hot.  Both of the solenoid's large posts and the left small post are hot (the right large post is connected to the right copper buss);  the other small post on the right is cold.
              SOLENOID
            H               H
                  h     c

     2) Lights (dashboard, headlights, driving lights, etc.) and wipers all work.
     3) The Kenwood screen will not power up.
     4) The Alladdin works (shows a red dot in all joystick locations) and can be operated from the bedroom joystick on the bedroom TV.

With the key in the START position:
     1) Neither the C-12 or generator will start.
     2) (Identical to key ON position) In the electrical bay all three copper busses are hot.  Both of the solenoid's large posts and the left small post are hot (the right large post is connected to the right copper buss);  the other small post on the right is cold.
              SOLENOID
            H               H
                  h     c

In the battery compartment all five auto-style fuses in the fuse module are good.  Near the fuse module, closer to the engine, there is an identical solenoid as is found in the front electrical bay... with what appears to be a good rectifier/diode.
In the BIRD/Big Boy compartment (located immediately above the coach batteries), all six high amp fuses are good.  One 5 amp auto-style fuse attached to a solenoid is good.


We have not located locally a replacement rectifier-diode for the front electrical bay solenoid yet...  still looking.  The closest Radio Shack is either Pendleton or the Tri-Cities - 30 and 40 miles, respectively.  Before making the longer drive we are checking with local auto and parts dealers.

Conclusion:  Everything appears to be working except the engine starting functions (C-12 and generator) and the Kenwood.  What is common about these - a fuse under the dash or perhaps behind the electrical bay?  When I am sitting near the BIRD/Big Boy compartment it sounds like the charging function for the batteries is kicking in and out as I would normally expect from a fully charged battery bank.

[David T. Richelderfer]

I am thinking the small rectifier/diode on the electrical bay solenoid is not critical to the functioning of the solenoid.  I am thinking the solenoid should operate without it.  These small diodes mainly function to reduce/eliminate radio static - yes?  Could the lack of the rectifier/diode be the reason for the C-12 and generator not wanting to start?

By the way, the Radio Shack in Pendleton has two 2-packs of these rectifier/diodes...  $1.99 for a 2-pack.

[Gerald Farris]

David,
Is the 12V battery terminal on the starter solenoid hot? If not you have a misconnected/misrouted battery cable that supplies the starter. The same source supplies the generator. If the battery post on the starter is hot, does the starter solenoid engage when you try to start the engine?

Gerald

[David T. Richelderfer]

I am assuming the starter solenoid is that solenoid found in the front electrical bay which is connected to the right-most copper buss.  There is also an identical solenoid found at the rear of the coach in the battery compartment on the wall beside the 5-fuse module.  Both of these solenoids have the same part number.  I do not know if the solenoid in the rear battery compartment is involved in the starter function.

Regarding the front electrical bay solenoid, when the key is in the ON position making the right copper buss bar hot, then yes the solenoid is hot at the right large post... because the right large post is connected to that copper buss.  In fact, with the key ON three of the posts on this solenoid are hot - both large posts and the left small post.  The right small post is cold.

    SOLENOID with key on
            H               H
                  h     c

[Steve Huber Co-Admin]

David,
The solenoid in the front electrical bay is the ignition solenoid, not the starter solenoid. Not sure but I suspect the starter solenoid is located close to the starter. Gerald would probably know for sure.
I just went through the wiring diagrams again and  came to pretty much the same conclusion as Gerald. I don't see any other fuses or solenoids in the circuit Based on what you reported, most likely either a mis-wire or fried starter solenoids (which is doubtful).
Steve

[David T. Richelderfer]

Okay - working my way through this... learning definitions of what is what and trying to diagnose symptoms.

The solenoid in the front electrical bay is the IGNITION solenoid.  Can we make the assumption the solenoid found in the battery compartment near the fuse module is the STARTER solenoid?

The ignition solenoid seems to be okay.  It receives power from the right-most copper buss bar when the key is in the ON position... and with the key in the ON position the solenoid passes power across to the other large post.  Sooo... the ignition circuit is live when the key is in the ON position.

I have now checked the (what I assume is) the STARTER solenoid in the rear battery compartment.  With the key in the OFF position, it has power at one large post... the same large post as noted on the ignition solenoid.  I assume that is power coming from the batteries.
With the key in the ON position, there is no change... only the one large post is hot.  I think this is good.  Since the starter system has not been engaged, the starter solenoid hot/cold posts should not change.
With the key in the START position, there is still no change... only the one large post is hot.  I think this is bad.  With the key in the START position the starter solenoid should be engaged.  It is not engaging.

I am thinking that with the key in the START position the solenoid should have been activated with power flowing through the large posts to the engine's starter.  Sooo... either that STARTER solenoid is bad or the link between the key and the starter solenoid is broken... by a blown fuse under the dash perhaps?  I am thinking when the key is in the START position, then the starter solenoid should have the same hot/cold posts (2 large posts and one small post hot, and one small post cold) as the ignition solenoid when the key is in the ON position.

Now keep in mind that somewhere between the generator start button and the generator starter there should be a starter solenoid.  That generator starter solenoid also is not engaging.

This all points to a blown fuse(?) after the ignition solenoid and before the key switch and generator start button.

I think I should crawl under the engine to look for more solenoids... especially a solenoid near the starter.  My assumption that what I have now been defining the starter solenoid may be another system's solenoid.  So I will do a bit more research under the coach's engine.

[Gerald Farris]

David,
The starter solenoid is bolted to the starter, directly above the starter motor.

Gerald

[Edward Buker]

David,

You are right about the diode in the electrical bay, it is not critical, it shorts out the voltage spike that is generated when the mag field in the solenoid collapses when you turn the ignition off. It is good to have to protect electronics but that can come later.

All you are doing with that solenoid is powering up the copper buss of accessories that turn on with the ignition switch. All the relays connected to that buss now have available power, like wipers, lights, dash fan etc. The solenoid in the battery compartment I believe is the one that parallels the battery banks for emergency starting. If some one hits that switch on the side console you should be able to hear it click and confirms that is its function.

 The solenoids that we are referring to reside on the starters themselves. They are more long cylinder arrangements on the side of the starter. When you turn on the ignition key to the start position the electromagnet portion throws the starter flywheel engagement gear forward, when that is in place and the throw is complete at the end of that stroke is a contactor that engages the heavy current circuit and connects it to the starter. On both of the starter solenoid there is a smaller 12V wire that should have 12 V applied when the respective starter switch is engaged (key on dash for engine, rocker for the genset). You need to also measure the larger cable that terminates at the starter solenoid and see if 12V is constantly present. If you do not have 12V on the large cable something is open/disconnected in the large cable coming from the battery bank. If you have 12V on the large wire but not the small wire going to the starter solenoid while in the start position then it is an open going to or coming from the starter switch which could still be a fuse/breaker somewhere. This will take some tracing.

In some cases the starter solenoid can be separate from the starter but I do not think we are dealing with that case here.

Later Ed

[Joel Ashley]

I'm no expert, but I've yet to see a starter that didn't have its solenoid attached to it, so voltage flows straight to the starter rather than through more wire beyond the heavy contacts, but I certainly haven't seen every application.  The solenoid in the bat compartment was replaced once while I was at BCS, but was associated with a faulty salesman's switch.  I can't remember what the techs and Ken called it, but don't think it was associated with the starter.

You need to crawl under the coach.
Joel

[Edward Buker]

Dave,

I find myself on Tengonet in Seattle area and I can use the forum but the forum will not let me post a photo evidently over Tengonet. I tried to send you a photo of the starter/solenoid arrangement via Email but I think your Email address on the forum may not be up to date.

Later Ed

[David T. Richelderfer]

My email address is dtrjb5331@gmail.com.  Yes, there is a smaller cylinder on top of the starter... and I thought it might be the starter solenoid.  As you(s) say, most often the starter solenoid is mounted on the starter motor.  The problem is that solenoid is virtually impossible to access.  I can see one large red-banded wire going to that solenoid coming directly from the chassis battery bank.  There is also a smaller wire attached to that solenoid coming in from above the starter, but I have no idea from where.  Also, there are three large black-banded wires attached directly to the starter body and all at one point.

You are correct in that I neglected to change my email address after a change.  I have now done that and am awaiting validation from the admin.  The updated email address is that one I entered above.