On the Road Electrical Trouble-shooting

B

brian krikorian

New member
Aug 25, 2017
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Hi everyone. I just drove my GMC from Seattle to LA. It was (thankfully) a rather uneventful trip mechanically, except for one hiccup. I am hoping
I can get some 2-cent feedback here while I try to fix/diagnose the problem before the trip back. Sorry in advance for the detail.

On the way down from Seattle, I stopped ¾ of the way into Oregon for a Walmart pit-stop. While I was there, I left the roof fan running (which I
assume draws on the house batteries) but did have a couple minor chassis battery draws (the radio and compressor) that are powered on. When I got
back after about 45 minutes, and tried to start the MH nothing happened (i.e. no turn over or sound). I had about 12.5 showing on my various voltage
meters. I tried boost, and nothing happened. I then used my "Jump Starter" and nothing happened. Finally someone offered a jump. The voltage meter
went to 13, and it started. I stopped for gas, and it restarted. I got to campground #1 and I plugged in (I also used a battery tender on the
chassis battery).

The next day I stopped at a rest stop outside of Redding, Ca. This time, I left the roof fan running again, but turned everything else off. Same
thing happened and nothing worked to get it started. I tried disconnecting the wires from the battery and connect it directly to my "jump starter"
and that didn't work. When I put the connectors back on the battery, the only eventful item was I hit the chassis and sparked the battery. I went
back in, and lo and behold it started. I stopped for gas, and I left the motor home running. I made it to the campground in Sacramento, and shut off
the engine. I then tried to restart, and nothing. I took the dogs for a walk, plugged in, came back 10 minutes later, it started. I also noted that
my house batteries were drained much more than usual. I tried starting several times over the next 12 hours and it worked each time (battery tender
hooked up).

Day 3: I drove straight to LA from Sacramento. I made two short stops (rest stop and gas) and kept the engine running the whole time. I made it to
my mom's house, and turned off the engine. This time I didn't have the roof fan running the entire time. My voltage showed 12.3-12.5. I tried to
restart, nothing. I plugged in the battery tender, hooked it to the chassis battery......got inside and cranked it....the motorhome turned over.

A few other things: In January my alternator was replaced, there were new wires put in, and a new battery. About 8 months ago I put in a new
isolator. Finally, whenever I used to turn the key to start, I'd hear a buzzing sound for a second (which I am assuming was the boost solenoid). I
didn't hear that buzzing over the last couple days, even when fully charged.

So I'm planning to run through all the connections I can, and make sure that the connections are good and clean. The other alternative is that my
"new" battery is not holding a charge, but that seems odd since when I hooked up the lines directly to my jump starter, it still didn't start.
Finally, I'm wondering if the boost solenoid is bad. Although I don't know enough if that would cause this kind of problem. The good news is I'm in
LA until next Monday, so I can hopefully make any "small fixes" while I'm here.

Also, I'm assuming the item with the Blue Arrow below is the boost solenoid? I also have two other batteries (Green Arrow) that are hooked up, as
well as two batteries next to the generator. I'm assuming the Green Arrow batteries are for extra boost?

http://www.gmcmhphotos.com/photos/member-galleries/p64949-boost-solenoid-and-batteries.html

Finally, if I need a new boost solenoid, does anyone have an idea of the part I order and where? I saw in earlier forum posts someone mentioned a
Napa part, but when I checked it, it said it was a "starter solenoid".

Any suggestions would be appreciated.

--
Brian K
1977 Eleganza II, TZE167V100261
Bellevue, WA
Rebuilt 455, New brake system, a lot of Original Equipment ready to fall apart (discovering more as I go along....)
 
A little more description during the "won't start" event may go a long way toward helping diagnose this. When it doesn't start does it;
- go completely dead (items like lights and gauges go dead too)
- no noise but dash lights and other electrical items work (like the ignition switch isn't connected to anything)
- there is a definite "click" but starter doesn't crank
- starter cranks but no start (no cyl firing)

Based on your description i interpret it is #2 but please verify (and I'd suspect an ignition switch or neutral switch.)
--
Chris Geils - Twin Cities / W Wa
1978 26' Kingsley w/ very few mods; Headers, PD9040, aux trans cooler, one repaint in stock colors, R134a, Al rad, Alcoas, 50k mi
 
> Hi everyone. I just drove my GMC from Seattle to LA. It was (thankfully) a rather uneventful trip mechanically, except for one hiccup. I am
> hoping I can get some 2-cent feedback here while I try to fix/diagnose the problem before the trip back. Sorry in advance for the detail.
>
> On the way down from Seattle, I stopped ¾ of the way into Oregon for a Walmart pit-stop. While I was there, I left the roof fan running (which I
> assume draws on the house batteries) but did have a couple minor chassis battery draws (the radio and compressor) that are powered on. When I got
> back after about 45 minutes, and tried to start the MH nothing happened (i.e. no turn over or sound). I had about 12.5 showing on my various
> voltage meters. I tried boost, and nothing happened. I then used my "Jump Starter" and nothing happened. Finally someone offered a jump. The
> voltage meter went to 13, and it started. I stopped for gas, and it restarted. I got to campground #1 and I plugged in (I also used a battery
> tender on the chassis battery).
>
> The next day I stopped at a rest stop outside of Redding, Ca. This time, I left the roof fan running again, but turned everything else off. Same
> thing happened and nothing worked to get it started. I tried disconnecting the wires from the battery and connect it directly to my "jump starter"
> and that didn't work. When I put the connectors back on the battery, the only eventful item was I hit the chassis and sparked the battery. I went
> back in, and lo and behold it started. I stopped for gas, and I left the motor home running. I made it to the campground in Sacramento, and shut
> off the engine. I then tried to restart, and nothing. I took the dogs for a walk, plugged in, came back 10 minutes later, it started. I also
> noted that my house batteries were drained much more than usual. I tried starting several times over the next 12 hours and it worked each time
> (battery tender hooked up).
>
> Day 3: I drove straight to LA from Sacramento. I made two short stops (rest stop and gas) and kept the engine running the whole time. I made it
> to my mom's house, and turned off the engine. This time I didn't have the roof fan running the entire time. My voltage showed 12.3-12.5. I tried
> to restart, nothing. I plugged in the battery tender, hooked it to the chassis battery......got inside and cranked it....the motorhome turned
> over.
>
> A few other things: In January my alternator was replaced, there were new wires put in, and a new battery. About 8 months ago I put in a new
> isolator. Finally, whenever I used to turn the key to start, I'd hear a buzzing sound for a second (which I am assuming was the boost solenoid). I
> didn't hear that buzzing over the last couple days, even when fully charged.
>
> So I'm planning to run through all the connections I can, and make sure that the connections are good and clean. The other alternative is that my
> "new" battery is not holding a charge, but that seems odd since when I hooked up the lines directly to my jump starter, it still didn't start.
> Finally, I'm wondering if the boost solenoid is bad. Although I don't know enough if that would cause this kind of problem. The good news is I'm
> in LA until next Monday, so I can hopefully make any "small fixes" while I'm here.
>
> Also, I'm assuming the item with the Blue Arrow below is the boost solenoid? I also have two other batteries (Green Arrow) that are hooked up, as
> well as two batteries next to the generator. I'm assuming the Green Arrow batteries are for extra boost?
>
> http://www.gmcmhphotos.com/photos/member-galleries/p64949-boost-solenoid-and-batteries.html
>
> Finally, if I need a new boost solenoid, does anyone have an idea of the part I order and where? I saw in earlier forum posts someone mentioned a
> Napa part, but when I checked it, it said it was a "starter solenoid".
>
> Any suggestions would be appreciated.

--
C. Boyd
76 Crestmont
East Tennessee
 
Chris,

Yes. #2. I get no clicking or sound. Lights and other 12v items work. The Volt meters read about 12v
--
Brian K
1977 Eleganza II, TZE167V100261
Bellevue, WA
Rebuilt 455, New brake system, a lot of Original Equipment ready to fall apart (discovering more as I go along....)
 
Sir, I just went thru this no start sometimes sorta thing with a very intelligent friend. Me here and him there and wanting me to diagnose. I said
to check battery connection and go from there. Guess what, he shook the good looking battery cable and it fell off. A blind monkey gets a nut
sometimes..
--
C. Boyd
76 Crestmont
East Tennessee
 
Yes....connections are going to definitely be the first thing I start going through
--
Brian K
1977 Eleganza II, TZE167V100261
Bellevue, WA
Rebuilt 455, New brake system, a lot of Original Equipment ready to fall apart (discovering more as I go along....)
 
Brian:

Yes - the blue arrow is pointing at the boost solenoid.

When the boost solenoid is “turned on” - it connects the large terminals on either side together. One side is normally the chassis and the other side is the coach/house/RV. When turned on, it’s kind of like connecting booster cables from the coach to the chassis. It’s basically a starter solenoid, being used to connect two circuits together (briefly).

The dash switch that turns on the boost solenoid would normally only be used in rare (!) cases where the chassis battery is too low to start, or possibly when coach battery is too low to start the generator. When you turn on the boost switch, the boost solenoid should “click” as it connects both sides together. When turned off - it should “click” again as they are disconnected from one another.

The boost solenoid should not normally be clicking or buzzing when turning on the ignition or during starting. It wouldn’t normally be enabled during a typical start - only when you click “boost” and try to start. And it wouldn’t normally buzz - unless perhaps the voltage is so low the solenoid turns off and on as the voltage fluctuates. You can manually turn on the boost solenoid by applying 12V to it - it should “click” and connect both large terminals together.

If your connections are good (which they may not be!) - the boost switch will gang all connected batteries together to get you started. In my Royale - I have one group 27 chassis battery (front) and two coach batteries - a 24 (front) and 27 (rear). My coach batteries are switched - so in theory I could gang all three of my batteries together to get me started.

The isolator keeps also keeps the chassis and coach separate - it keeps one side from draining the other side (which could also happen if the boost solenoid was turned on when not needed), unless charging.

I can’t really tell from you picture how the green batteries are connected. I assume that you have just one chassis battery? The chassis battery should be connected to one side of the boost solenoid and one terminal of the isolator. The coach batteries will be on the other side of both the boost solenoid and the isolator.

Hope it helps - likely not!

Rob
Victoria, BC
76 Royale - Rear Twins/Dry Bath

>
> Hi everyone. I just drove my GMC from Seattle to LA. It was (thankfully) a rather uneventful trip mechanically, except for one hiccup. I am hoping
> I can get some 2-cent feedback here while I try to fix/diagnose the problem before the trip back. Sorry in advance for the detail.
>
> On the way down from Seattle, I stopped ¾ of the way into Oregon for a Walmart pit-stop. While I was there, I left the roof fan running (which I
> assume draws on the house batteries) but did have a couple minor chassis battery draws (the radio and compressor) that are powered on. When I got
> back after about 45 minutes, and tried to start the MH nothing happened (i.e. no turn over or sound). I had about 12.5 showing on my various voltage
> meters. I tried boost, and nothing happened. I then used my "Jump Starter" and nothing happened. Finally someone offered a jump. The voltage meter
> went to 13, and it started. I stopped for gas, and it restarted. I got to campground #1 and I plugged in (I also used a battery tender on the
> chassis battery).
>
> The next day I stopped at a rest stop outside of Redding, Ca. This time, I left the roof fan running again, but turned everything else off. Same
> thing happened and nothing worked to get it started. I tried disconnecting the wires from the battery and connect it directly to my "jump starter"
> and that didn't work. When I put the connectors back on the battery, the only eventful item was I hit the chassis and sparked the battery. I went
> back in, and lo and behold it started. I stopped for gas, and I left the motor home running. I made it to the campground in Sacramento, and shut off
> the engine. I then tried to restart, and nothing. I took the dogs for a walk, plugged in, came back 10 minutes later, it started. I also noted that
> my house batteries were drained much more than usual. I tried starting several times over the next 12 hours and it worked each time (battery tender
> hooked up).
>
> Day 3: I drove straight to LA from Sacramento. I made two short stops (rest stop and gas) and kept the engine running the whole time. I made it to
> my mom's house, and turned off the engine. This time I didn't have the roof fan running the entire time. My voltage showed 12.3-12.5. I tried to
> restart, nothing. I plugged in the battery tender, hooked it to the chassis battery......got inside and cranked it....the motorhome turned over.
>
> A few other things: In January my alternator was replaced, there were new wires put in, and a new battery. About 8 months ago I put in a new
> isolator. Finally, whenever I used to turn the key to start, I'd hear a buzzing sound for a second (which I am assuming was the boost solenoid). I
> didn't hear that buzzing over the last couple days, even when fully charged.
>
> So I'm planning to run through all the connections I can, and make sure that the connections are good and clean. The other alternative is that my
> "new" battery is not holding a charge, but that seems odd since when I hooked up the lines directly to my jump starter, it still didn't start.
> Finally, I'm wondering if the boost solenoid is bad. Although I don't know enough if that would cause this kind of problem. The good news is I'm in
> LA until next Monday, so I can hopefully make any "small fixes" while I'm here.
>
> Also, I'm assuming the item with the Blue Arrow below is the boost solenoid? I also have two other batteries (Green Arrow) that are hooked up, as
> well as two batteries next to the generator. I'm assuming the Green Arrow batteries are for extra boost?
>
> http://www.gmcmhphotos.com/photos/member-galleries/p64949-boost-solenoid-and-batteries.html
>
> Finally, if I need a new boost solenoid, does anyone have an idea of the part I order and where? I saw in earlier forum posts someone mentioned a
> Napa part, but when I checked it, it said it was a "starter solenoid".
>
> Any suggestions would be appreciated.
>
> --
> Brian K
> 1977 Eleganza II, TZE167V100261
> Bellevue, WA
> Rebuilt 455, New brake system, a lot of Original Equipment ready to fall apart (discovering more as I go along....)
 
Rob,

Thanks. That is hepful.

So, I have a chassis battery in the driver side compartment. Then there are these two batteries (in the picture, and I'm guessing two 6vs). I think
they go to the boost side. Then i have two house batteries in the back. This is how I got the coach
--
Brian K
1977 Eleganza II, TZE167V100261
Bellevue, WA
Rebuilt 455, New brake system, a lot of Original Equipment ready to fall apart (discovering more as I go along....)
 
The next time it won't start, put the gear shift selector in 1, then into P
and tilt the steering wheel towards the windshield. Let us know what
happens.
Jim Hupy

> Rob,
>
> Thanks. That is hepful.
>
> So, I have a chassis battery in the driver side compartment. Then there
> are these two batteries (in the picture, and I'm guessing two 6vs). I think
> they go to the boost side. Then i have two house batteries in the back.
> This is how I got the coach
> --
> Brian K
> 1977 Eleganza II, TZE167V100261
> Bellevue, WA
> Rebuilt 455, New brake system, a lot of Original Equipment ready to fall
> apart (discovering more as I go along....)
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
You have a lot of extra (different) stuff there from the way the coach was designed. The extra stuff makes remote diagnosis difficult because we do
not know exactly what you have there. So my approach will be to explain the two 12 DC electrical systems that you have in the coach as shipped by GM
in 1977.

There are two 12 volt DC systems. They are the engine side and the house side. There is NO Boost system with it's own batteries. There is a VERY
SELDOM USED boost function that temporarily attaches the house and engine batteries together for extra starting power in the case of one battery
(house or engine) being low. This is so seldom used that on my coach I have never, ever needed it. This function is activated by pressing and
holding down a rocker switch on dash.

So back to the two systems.

The engine side normally has one battery located above the right front wheel. I supplies all power for starting the engine and things you expect to
see in a car. Things like headlights, brake lights, clearance lights, front only interior lights, radio, and heater fan. If it is an outside light
or and item located in front of the cockpit step is is probably powered by the engine 12 DC system.

The house side in a 1977 26 ft coach is normally powered by one or two batteries located in the left rear of the coach next to the Onan. Everything
not mentioned in the previous paragraph is probably powered by the house battery(s) system.

That is it and things like blue and green arrows and a battery mounted on the driver's side front mean nothing to us because they are non-standard
add-ons.

All of that said, I can not see why these non-standard add-ons would be on the engine side of things. People usually install that stuff to extend /
expand the house system. There is really no reason that they would be needed on the engine side.

So I would check the engine battery and check it's connections and ignore everything else we think is on the house side. From your symptom I strongly
suspect that one of the following items are failing or out of adjustment in the following order. The neutral safety switch, the ignition switch, the
start solenoid coil, and wires/ connections to any of them.

They next time that you have the failure, while it is failing turn on the headlights and try starting the engine. If the engine fails to crank and
the headlights stay on then you do NOT have a battery power supply problem. If the headlights dim, then you need to go find the bad battery
connection or weak battery.

That should get you started diagnosing the problem. Also the next time is fails try moving the gear shift up and down while trying to crank. That
will move / exercise the neutral safety switch a bit.

Good Luck

Ken B.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
Thanks everyone for the tips and advice.

Ken, I understand what you're saying. I think the two front, passenger side batteries ARE there for the house. But I do see wires going from them to
one side of the boost solenoid. Again it's a hodgepodge mess for me, so I certainly understand it making no sense remotely or by description.

That said I'm going to start with the easiest and look at the wires and connections. I will follow your and Jim's suggestions if it happens again
after that.

Brian
--
Brian K
1977 Eleganza II, TZE167V100261
Bellevue, WA
Rebuilt 455, New brake system, a lot of Original Equipment ready to fall apart (discovering more as I go along....)
 
There is no problem with the hodge podge as long as you understand what is doing what.

I will suggest that the heaviest current draw item in the coach is the starter. For that reason you want the cables to be as short and clean as
possible to the battery. So the engine battery should located on the passenger side front.

--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
>
> From your symptom I strongly suspect that one of the following items are failing or out of adjustment in the following order. The neutral safety switch, the ignition switch, the start solenoid coil, and wires/ connections to any of them.

No suggestions but an anecdote...

After gassing up my Dakota, ignition gave one click, then nothing. Same again. I turned the wheel, shifted back and forth to Park, put my foot on the brake and when I turned the key again, it started right up.

Happened again a week or so later with same result. Week or so later, happened again but this time it took more of the turning, shifting procedure to work, Started happening more frequently, and more difficulty to start. As my mechanic just started his vacation, I stopped by an Auto Electric shop I know, and asked them to test the alternator. Alt and battery both tested good, and he suggested it might be the neutral safety switch.

During mech’s vacation, one morning it wouldn’t start at all. I did check around the internet and neutral safety switch did look like a good possibility. Taking stock of my mechanical skills, I wisely decided to not try replacing it myself. Upon his return, one morning I did get it started and drove it to his shop. I imparted my wisdom of likely neutral safety switch and left him to it. He called later, said it was the starter, replaced it and I haven’t had an issue since.

Tim Conway
LI NY 78 PB
 
Chuck,

Good advice but you got to get your sayings straight, they are; "a blind monkey sometimes gets a banana" and "a blind squirrel
sometimes gets a nut."

:-)

Regards,
Rob M.
The Pedantic Mechanic
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
USA '77 Kingsley - TZE 267V100808


-----Original Message-----
From: Gmclist [mailto:gmclist-bounces] On Behalf Of Charles Boyd
Sent: Tuesday, July 3, 2018 9:07 PM
To: gmclist
Subject: Re: [GMCnet] On the Road Electrical Trouble-shooting

Sir, I just went thru this no start sometimes sorta thing with a very intelligent friend. Me here and him there and wanting me to
diagnose. I said to check battery connection and go from there. Guess what, he shook the good looking battery cable and it fell
off. A blind monkey gets a nut
sometimes..
--
C. Boyd
 
You should not travel without a $10 DVM (meter) and understanding of the DCV function. At this point I would charge all the batteries via an external
charger and have them load tested. Replace as needed. Then after cleaning all terminals (connect negative last remove first for no arcs) start the
motorhome. Meter across all your 12V batteries. You should see 13.4-14.2V. If you see below 13.2V your system is not charging and needs further
diagnosis. A 12V battery sitting fully charged should read 12.6V approx. If it reads 12V it is mostly dead and needs full charging or replaced
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
I did not suggest the starter in his case because he is not hearing the solenoid click. I am assuming that he is not getting +12 to the solenoid coil
or the solenoid coil is going bad.

Isn't remote diagnosis fun? It is all a guessing game.

Ken B.

> >
> > From your symptom I strongly suspect that one of the following items are failing or out of adjustment in the following order. The neutral
> > safety switch, the ignition switch, the start solenoid coil, and wires/ connections to any of them.
>
> No suggestions but an anecdote...
>
> After gassing up my Dakota, ignition gave one click, then nothing. Same again. I turned the wheel, shifted back and forth to Park, put my foot on
> the brake and when I turned the key again, it started right up.
>
> Happened again a week or so later with same result. Week or so later, happened again but this time it took more of the turning, shifting procedure
> to work, Started happening more frequently, and more difficulty to start. As my mechanic just started his vacation, I stopped by an Auto Electric
> shop I know, and asked them to test the alternator. Alt and battery both tested good, and he suggested it might be the neutral safety switch.
>
> During mech's vacation, one morning it wouldn't start at all. I did check around the internet and neutral safety switch did look like a good
> possibility. Taking stock of my mechanical skills, I wisely decided to not try replacing it myself. Upon his return, one morning I did get it
> started and drove it to his shop. I imparted my wisdom of likely neutral safety switch and left him to it. He called later, said it was the starter,
> replaced it and I haven't had an issue since.
>
> Tim Conway
> LI NY 78 PB
>
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
Yes Rob, but I don't have any banana trees, just nuts.

http://www.gmcmhphotos.com/photos/member-galleries/p64954-bad-cable.html

> Chuck,
>
> Good advice but you got to get your sayings straight, they are; "a blind monkey sometimes gets a banana" and "a blind squirrel
> sometimes gets a nut."
>
> :)
>
> Regards,
> Rob M.
> The Pedantic Mechanic
> Sydney, Australia
> AUS '75 Avion - The Blue Streak TZE365V100428
> USA '75 Avion - Double Trouble TZE365V100426
> USA '77 Kingsley - TZE 267V100808
>
>
>
> -----Original Message-----
> From: Gmclist [mailto:gmclist-bounces] On Behalf Of Charles Boyd
> Sent: Tuesday, July 3, 2018 9:07 PM
> To: gmclist
> Subject: Re: [GMCnet] On the Road Electrical Trouble-shooting
>
> Sir, I just went thru this no start sometimes sorta thing with a very intelligent friend. Me here and him there and wanting me to
> diagnose. I said to check battery connection and go from there. Guess what, he shook the good looking battery cable and it fell
> off. A blind monkey gets a nut
> sometimes..
> --
> C. Boyd
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

--
C. Boyd
76 Crestmont
East Tennessee
 
Actualy, you can laer more from an analog meter:

https://www.ebay.com/itm/TY-360-Ohm-Ampere-Volt-Diode-Measuring-Analog-Electrical-Meter-Multimeter/323102379979?epid=1538794366&hash=item4b3a670fcb:g:J4YAAOSwvmRalD2n

/because with these old toys we're usually more interested in trends than absolutes, and they're easier to see with a needle than a display. It's
alsoa good idea topinclude at least a chassis ammeter. Which I'm ashamed to admit I haven't put on the current coach.

--johnny

--
76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
"I forgive them all, save those who hurt the dogs. They must answer to me in hell" - ol Andy, paraphrased
 
Brian -

Where in LA are you ??

If you can get near Orange County this weekend - we could help with some diagnosis...

Steve W
1973 23
Southern California
 
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