Home » Public Forums » GMCnet » need help, dead on the road (electrical problem?)
| need help, dead on the road [message #186643] |
Sun, 07 October 2012 21:13  |
3mguy
Messages: 8
Registered: October 2012
Location: Plymouth MI
Karma: 0
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Junior Member |
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Just purchased my first GMC motorhome today! not going well so far. Got 250 miles down the road and it died. Here are the details.
It was running great, just cruise controlling it at 62mph. Everything working just fine. Noticed that I had a tilt wheel, so I adjusted it up. Lost power to my cruise control, turnsignals radio airbags and horn, but still driving. Getting dark so I turned on the lights. It killed power to the motor instantly. Turned lights off, engine turned back on with a huge backfire (blew the end of my tailpipe off). Still driving though so I kept going about 10 more miles. Then it just died, no ignition, nothing. getting it towed to my house tonight, but don't have a clue what to do next. Problem with the ignition switch? fwi.. It has a new Alternator. Car behind me said my brake lights went dim. Again, all was working great and I was happy with my purchase. now im stranded, can any body help figure this out? first time gmcer, first time forum poster (and reader) Thanks, Larry 734-834-5664 or larry@norockchips.com or i think i can read info right here. 
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| Re: need help, dead on the road [message #186644 is a reply to message #186643] |
Sun, 07 October 2012 21:33  |
GeorgeRud
Messages: 1380
Registered: February 2007
Location: Chicago, IL
Karma: 0
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There is a large multi-connector at the base of the steering column. I'd try to check that it didn't somehow get disconnected when you tilted the wheel.
Wiring diagrams are available for the Motorhome if you don't have one, but it sounds like you have quite a few circuits to trace.
Obviously, check the fuses in the glovebox as well.
Good luck!
George Rudawsky
Chicago, IL
75 Palm Beach
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| Re: need help, dead on the road [message #186645 is a reply to message #186643] |
Sun, 07 October 2012 21:36 |
John Sharpe
Messages: 489
Registered: February 2006
Location: Texas
Karma: 1
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Tilting the wheel could have caused the rod going to the ignition switch to move just enough to break the circuit feeding the alternator. This would cause a no charge situation, resulting in a drain on the battery. When you turned the lights on, they took enough juice to cause the voltage to drop below what was required to the ignition system to function so the engine died. Apparently you have a carburetor, so with your foot on the accelerator coasting without power resulted in a loading of the cylinders and exhaust with fuel. When you turned the lights off, there was enough voltage for the ignition system to function. It worked perfectly and ignited the bomb.
Look for a problem in the ignition switch area and/or the operating rod. The ignition switch in not where the key is located but rather on top of the steering column in the area above the brake pedal.
John Sharpe
Humble,TX
'78 Eleganza TBI
'89 Spectrum 2000 MPI V-10
'40 Ford Panel Delivery TPI
johnasharpe@gmail.com
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| Re: [GMCnet] need help, dead on the road [message #186649 is a reply to message #186643] |
Sun, 07 October 2012 21:42 |
Wayne Newland
Messages: 75
Registered: February 2004
Karma: 0
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Larry
Where are you? Do you have a copy of the "Black List" (a list of people
that may be able to help you)?
Wayne Newland F9300 75 Palm Beach Sebastian, Fl
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Larry Millen
Sent: Sunday, October 07, 2012 10:13 PM
To: gmclist@temp.gmcnet.org
Subject: [GMCnet] need help, dead on the road
Just purchased my first GMC motorhome today! not going well so far. Got 250
miles down the road and it died. Here are the details.
It was running great, just cruise controlling it at 62mph. Everything
working just fine. Noticed that I had a tilt wheel, so I adjusted it up.
Lost power to my cruise control, turnsignals radio airbags and horn, but
still driving. Getting dark so I turned on the lights. It killed power to
the motor instantly. Turned lights off, engine turned back on with a huge
backfire (blew the end of my tailpipe off). Still driving though so I kept
going about 10 more miles. Then it just died, no ignition, nothing.
getting it towed to my house tonight, but don't have a clue what to do next.
Problem with the ignition switch? fwi.. It has a new Alternator. Car behind
me said my brake lights went dim. Again, all was working great and I was
happy with my purchase. now im stranded, can any body help figure this out?
first time gmcer, first time forum poster (and reader) Thanks, Larry
734-834-5664 or mailto:larry@norockchips.com or i think i can read info
right here. :(
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| Re: need help, dead on the road [message #186650 is a reply to message #186643] |
Sun, 07 October 2012 21:46 |
Craig Lechowicz
Messages: 541
Registered: October 2006
Location: Waterford, MI
Karma: 0
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Senior Member |
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Larry,
I'm in Waterford, so if home is in Plymouth, I could potentially come out and look at it with you. From the overall description you gave, I would guess and say your biggest problem is you've discovered a key difference between a new alternator, and a working alternator (or the wiring for it). It sounds like the battery is quite low, which is why turning the headlights off helped for a while. It may be things like the cruise, radio and turn signals were affected by slowly dropping battery voltage prior to other things being apparent, or it may be they have their own issues. If you have a battery charger, charge the battery, ideally overnight. If you don't have a voltmeter, there will be one in your future as a GMC owner. After an overnight charge, it should start, and the voltmeter should be 14.0+ volts when running at a fast idle. If it's more like 12.6 or so, yo definitely have alternator or charging problems. Next steps from there are somewhat dependent on how comfortable you are working on things. Testing the voltage at the alternator itself would be good next, but takes some wiggling to get to. At any rate, that is a start.
Craig Lechowicz
'77 Kingsley, Waterford, MI
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| Re: need help, dead on the road [message #186652 is a reply to message #186643] |
Sun, 07 October 2012 21:53 |
A Hamilto
Messages: 4508
Registered: April 2011
Karma: 39
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Senior Member |
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| 3mguy wrote on Sun, 07 October 2012 21:13 |
Just purchased my first GMC motorhome today! not going well so far. Got 250 miles down the road and it died. Here are the details.
It was running great, just cruise controlling it at 62mph. Everything working just fine. Noticed that I had a tilt wheel, so I adjusted it up. Lost power to my cruise control, turnsignals radio airbags and horn, but still driving. Getting dark so I turned on the lights. It killed power to the motor instantly. Turned lights off, engine turned back on with a huge backfire (blew the end of my tailpipe off). Still driving though so I kept going about 10 more miles. Then it just died, no ignition, nothing. getting it towed to my house tonight, but don't have a clue what to do next. Problem with the ignition switch? fwi.. It has a new Alternator. Car behind me said my brake lights went dim. Again, all was working great and I was happy with my purchase. now im stranded, can any body help figure this out? first time gmcer, first time forum poster (and reader) Thanks, Larry 734-834-5664 or larry@norockchips.com or i think i can read info right here.
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I would guess the backfire was from the fuel that transited the engine unburned when it died due to lack of spark. It collected in the exhaust system and "exploded" when the engine started again.
As far as the engine not running, the symptoms would point to the alternator was not charging, and the battery was getting low. When you turned on the headlights, not enough juice was left to generate spark so it died. Could also be a short circuit somewhere in the light wiring. Kind of surprised it started, but another 10 miles and there wasn't enough battery to go any farther. If the Onan runs, start the Onan, flip the boost switch and see if the 455 will start and then see if the 455 can keep running with the headlights on.
Troubleshoot the ignition and charging systems when you get home.
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| Re: [GMCnet] need help, dead on the road [message #186661 is a reply to message #186652] |
Sun, 07 October 2012 22:07 |
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ljdavick
Messages: 3548
Registered: March 2007
Location: Fremont, CA
Karma: -3
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Senior Member |
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Excellent advice. If the Onan runs crank it up and throw the boost switch! Drive home. Also buy an alternator protection cable <http://www.appliedgmc.com/prod.itml/icOid/557>
Larry Davick
On Oct 7, 2012, at 7:53 PM, A. <markbb1@netzero.com> wrote:
>
>
> 3mguy wrote on Sun, 07 October 2012 21:13
>> Just purchased my first GMC motorhome today! not going well so far. Got 250 miles down the road and it died. Here are the details.
>> It was running great, just cruise controlling it at 62mph. Everything working just fine. Noticed that I had a tilt wheel, so I adjusted it up. Lost power to my cruise control, turnsignals radio airbags and horn, but still driving. Getting dark so I turned on the lights. It killed power to the motor instantly. Turned lights off, engine turned back on with a huge backfire (blew the end of my tailpipe off). Still driving though so I kept going about 10 more miles. Then it just died, no ignition, nothing. getting it towed to my house tonight, but don't have a clue what to do next. Problem with the ignition switch? fwi.. It has a new Alternator. Car behind me said my brake lights went dim. Again, all was working great and I was happy with my purchase. now im stranded, can any body help figure this out? first time gmcer, first time forum poster (and reader) Thanks, Larry 734-834-5664 or larry@norockchips.com or i think i can read info right here. :(
> I would guess the backfire was from the fuel that transited the engine unburned when it died due to lack of spark. It collected in the exhaust system and "exploded" when the engine started again.
> As far as the engine not running, the symptoms would point to the alternator was not charging, and the battery was getting low. When you turned on the headlights, not enough juice was left to generate spark so it died. Could also be a short circuit somewhere in the light wiring. Kind of surprised it started, but another 10 miles and there wasn't enough battery to go any farther. If the Onan runs, start the Onan, flip the boost switch and see if the 455 will start and then see if the 455 can keep running with the headlights on.
> Troubleshoot the ignition and charging systems when you get home.
> --
> '73 23' Sequoia
> UA (Upper Alabama)
> _______________________________________________
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Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, Ca
Howell EFI + EBL + Electronic Dizzy
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| Re: [GMCnet] need help, dead on the road [message #186662 is a reply to message #186658] |
Sun, 07 October 2012 22:11 |
John Sharpe
Messages: 489
Registered: February 2006
Location: Texas
Karma: 1
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Senior Member |
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Pushing the boost switch on the dash should allow you to start the coach on the house battery. Juggle on the key to make sure everything is working ie turnsignals radio airbags and horn. If they are then it is a problem with the control rod from the ignition key cylinder to the igniton switch. Most likely you DO NOT have an electrical problem!
John Sharpe
Humble,TX
'78 Eleganza TBI
'89 Spectrum 2000 MPI V-10
'40 Ford Panel Delivery TPI
johnasharpe@gmail.com
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| Re: need help, dead on the road [message #186663 is a reply to message #186660] |
Sun, 07 October 2012 22:18 |
John Sharpe
Messages: 489
Registered: February 2006
Location: Texas
Karma: 1
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Senior Member |
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| Quote: |
I am home Very Happy , the motorhome is in my driveway (not under its own power)Now I have a project. Anybody know how far you can drive without the charging system working? Im sure not 200+ miles, but I just remembered something else... The guy I bought it from had a charging light come on. He thought it was the alternater, so put a new one on. No change. he disconnected something on the fire wall (pass side) and connected two wires together and left one hanging. I think he said it was a regulator. I have the part in my hand. I did drive the motorhome for 4 hours though before the problems started.
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Larrys, that 'regulator' is probably the isolator so the coach battery is not being charged. The previous owner bypassed it and only hooked the chassis battery to the alternator.
John Sharpe
Humble,TX
'78 Eleganza TBI
'89 Spectrum 2000 MPI V-10
'40 Ford Panel Delivery TPI
johnasharpe@gmail.com
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| Re: need help, dead on the road [message #186665 is a reply to message #186643] |
Sun, 07 October 2012 22:34 |
Craig Lechowicz
Messages: 541
Registered: October 2006
Location: Waterford, MI
Karma: 0
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Senior Member |
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There are a lot of variables to how far it will run without charging. When I 1st picked mine up, it ran from Owosso to Hartland, a bit over an hour with the alternator not working. Still running when I got there, and the leveling compressor was running a lot during the trip. It sounds like the thing on the firewall you have off is the isolator, (usually a box with aluminum fins, give or take fist sized, but taller) which uses diodes to charge both the engine ("chassis") battery and the "house" (interior lights, fresh water pump, etc.) batteries while the engine is running, and separate or isolate them when the engine is not running. So, if those wires are hooked together, and all the batteries are charged and hooked together where the isolator was, and you didn't have lights on, or the heater fan, or the air leveling compressor running a lot, you very well might be able to make it 250 miles with both sets of batteries hooked together. If all that is true, the Onan probably won't start, as the house batteries will be low as well. Plus, for it to help much, you have to have a working converter or modern replacement for it.
Unfortunately previous owners "solutions" and electrical wiring are sometimes less than obvious or effective. (I'm sure someday, the future owner of my coach will wonder what the heck I was thinking). But, it does make me feel it's more of a charging issue than steering column/switches/wiring stuff.
Craig Lechowicz
'77 Kingsley, Waterford, MI
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| Re: [GMCnet] need help, dead on the road [message #186667 is a reply to message #186643] |
Sun, 07 October 2012 22:46 |
powerjon
Messages: 2446
Registered: January 2004
Karma: 5
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Senior Member |
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Larry,
You have gotten a lot of advice in the last few hours.
Before you start tearing anything apart, charge the battery. If the
coach starts and everything work again you have a bad alternator or
battery isolator or possible a bad battery. Quick check on the
alternator with the engine running is put the heater fan in high speed
and if you have no blower the alternator is bad. Alternator should be
putting out around 14 + VDC and you should see that on all terminals
of the isolator. 13.6 VDC is probably OK too.
JR Wright
78 Buskirk Stretch
Michigan
On Oct 7, 2012, at 10:13 PM, Larry Millen wrote:
>
>
> Just purchased my first GMC motorhome today! not going well so far.
> Got 250 miles down the road and it died. Here are the details.
> It was running great, just cruise controlling it at 62mph.
> Everything working just fine. Noticed that I had a tilt wheel, so I
> adjusted it up. Lost power to my cruise control, turnsignals radio
> airbags and horn, but still driving. Getting dark so I turned on
> the lights. It killed power to the motor instantly. Turned lights
> off, engine turned back on with a huge backfire (blew the end of my
> tailpipe off). Still driving though so I kept going about 10 more
> miles. Then it just died, no ignition, nothing. getting it towed
> to my house tonight, but don't have a clue what to do next. Problem
> with the ignition switch? fwi.. It has a new Alternator. Car behind
> me said my brake lights went dim. Again, all was working great and
> I was happy with my purchase. now im stranded, can any body help
> figure this out? first time gmcer, first time forum poster (and
> reader) Thanks, Larry 734-834-5664 or mailto:larry@norockchips.com
> or i think i can read info right here. :(
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
_______________________________________________
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J.R. Wright
GMC GreatLaker
GMC Eastern States
GMCMI
78 30' Buskirk Stretch
75 Avion Under Reconstruction
Michigan
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, the motorhome is in my driveway (not under its own power)Now I have a project. Anybody know how far you can drive without the charging system working? Im sure not 200+ miles, but I just remembered something else... The guy I bought it from had a charging light come on. He thought it was the alternater, so put a new one on. No change. he disconnected something on the fire wall (pass side) and connected two wires together and left one hanging. I think he said it was a regulator. I have the part in my hand. I did drive the motorhome for 4 hours though before the problems started. 