Go Back   iRV2 Forums > MOTORHOME FORUMS > Class A Motorhome Discussions
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
Thread Tools Search this Thread Display Modes
Old 02-09-2010, 12:56 PM   #1
Junior Member
Join Date: Feb 2010
Posts: 10
1999 Monaco Diplomat gauge problems

We just purchased a 1999 Monaco Diplomat 38'. I have a problem with the dash wiring. When I pull the head light swith on to either the headlights or marker lights I get a reaction on several of the gauges. When I turn the switch knob to dim or brighten the dash lights the gauges also alter. When I turn the dash lights off the gauges return to normal. Has anyone else had this problem? Just joined this group and looks like a really interesting bunch.

Any ideas would be appreciated.


Merv is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 02-09-2010, 02:27 PM   #2
Senior Member
skipwil's Avatar
Fleetwood Owners Club
Appalachian Campers
Join Date: Aug 2007
Location: Greeneville-North East Tn.
Posts: 632
Welcome to The BEST forum on RV'ing.
My experience in car & truck repairs on dashes and wiring; it comes down to a loose ground wire some where under the dash or around the steering column. The ground circuit goes many places so don't be surprised if it's far from the problem. Patience is the best advice I can give you. If you remove the dash panel you might be able to use a ground jumper wire to re-connect a ground circuit between the strg/column and the light panel. If you do connect the ground and all returns to normal light wise & gauges you then have a choice- either use the extra ground wire or find the loose connection. Please let us know if you have a success outcome.
I hope this helps.
Again Welcome to The FORUM.
Safe Travels/Ck our website below

JOE.. LEO(ret.)-active USCGAUX-
ck. our website:www.overmountainsams.com
skipwil is offline   Reply With Quote
Old 03-07-2010, 10:05 AM   #3
Senior Member
tomgagne's Avatar
Join Date: Mar 2009
Location: Abington, Ma
Posts: 159
Merv, you'll find more information in the Monaco forum. The Monaco's are known for grounding issues as skipwil mentions. I have a 2002 diplomat which does the same thing as yours. Originally I thought it was the lightswitch because the dimming effect wasn't linear when I turned the switch. I replaced the switch and the dimming effect is better but the guages still move significantly (voltage guage) when I turn the headlights on and turn the dimmer up to the max. The guages settle down when I turn off the dashlights.
tomgagne is offline   Reply With Quote
Old 03-07-2010, 11:40 AM   #4
Senior Member
PlayItForwrd's Avatar
Tiffin Owners Club
Join Date: Feb 2010
Posts: 315
Most electric gauges work on ground resistance. If you have questionable grounds somewhere, that'll affect the gauges. What will also make the gauges 'react' is voltage drops. As the voltage to an electric gauge drops, it's reading will typically read higher (the exception would be a volt gauge!). Motorhomes have miles of wiring. Many rigs will run high-amp devices like headlights using solenoids to reduce voltage drop. However, there's still the bazillion markers and taillights connected to a mile of wiring that won't be connected to a solenoid, and the resistance can cause quite a voltage drop. Add a loose ground wire anywhere in the mix, and the gauges WILL be affected.

Our houseboat has 2 helms with full gauges, and all the gauges change depending on which ignition keys are on (or not) due to voltage drop. It's kind of frustrating, but I've gotten used to it--
2000 40' Tiffin Allegro Bus \ 2003 Chaparral 260 SSI
1988 53 x 14 Skipperliner \ 1995 32' Party Cruiser
1984 Goldwing Aspencade \ 1976 Harley Sportster
PlayItForwrd is offline   Reply With Quote
Old 03-07-2010, 01:05 PM   #5
Senior Member
Papa_Jim's Avatar
Outdoors RV Owners Club
Join Date: Oct 2009
Location: Manitoba,Canada
Posts: 2,667
I've had all the symptoms you're talking about, and it was always a ground issue.

Yours may be different, but on mine you take all of the screws that hold the dash in place, and carefully pull it out toward the drivers seat, being careful not to disconnect anything. Up against the front bulkhead there's a silver buss bar. That's all of the ground connections. Using a screwdriver, and some contact cleaner, you loosen the connections a little, spray them, and tighten them down real tight.

You've got to find out where your buss ground bar is. Mine is on the front bulkhead up under the dash. Yours may be somewhere else.

Jim Sanderson
Canada, eh?
Jim & Kate
2016 Creekside 23RKS
2014 Ram 1500 4X4 Eco Diesel
Canada, eh?
Papa_Jim is offline   Reply With Quote
Old 03-08-2010, 09:53 AM   #6
Junior Member
Join Date: Feb 2010
Posts: 10
Thanks guys for your interest and input. I have gone over the connections that are visible and accessible without success. It looks like my next step is to have a go at the grounding buss behind the dash. I will let you know if I have any joy.

Thanks also for the warm welcome to this most interesting forum.

Merv is offline   Reply With Quote
Old 03-08-2010, 03:13 PM   #7
Junior Member
Join Date: Feb 2010
Posts: 10
Just to let you know that I took a jumper wire from one of the gauge ground terminals to the main ground terminal above the brake pedal and voila! my gauges are now working perfectly. Thanks to the guys in the Monaco forum for the additional info.

Cheers from Salt Spring Island


Merv is offline   Reply With Quote

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
Done Deal: Navistar Completes Purchase of Monaco for $47M DriVer RV Industry Press 13 05-12-2010 04:47 PM
2011 Monaco Diplomat 42 footer bigdomino Monaco Owner's Forum 9 03-19-2010 08:07 PM
Monaco Coach Corporation Signs Non-Binding Letter of Intent With Navistar, Inc. DriVer RV Industry Press 0 03-26-2009 07:17 PM
Transmission Fluid Filler on '00 Monaco Diplomat 38D BIGRED1 Allison Transmission Forum 3 09-03-2006 06:20 PM

» Featured Campgrounds

Reviews provided by

Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 03:26 PM.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2018, vBulletin Solutions, Inc.