Headlight Switch, and Headlights

[gwscuba]

Hi,

We are newbies and just took possession of a 99 Diplomat and have gained some information from Irv2 already that has helped with a few new discoveries (problems) of used coach ownership. Now I need a little more specific advice.

During testing, we noticed that the volt meter on the instrument panel was readying only ~ 10.5 v with the dimmer switch pulled, no headlight on, and the motor running. Without the running lights on, it reads 12.5v +. SO as I adjust the intensity of the gauge lights, it wll intermittently run the volts down to "zero" and back and forth. I'm guessing the headlight pull switch is bad. So my question is where can I buy a new switch, and how easy is it to replace?

Second question, from reading a few remarks about upgrading the headlights in a older coach, I am ready to add the 12v relay and get new bulbs, but I can't seem to be able to remove the old bulbs and find out which one I'll need to replace with a new generation bulb. Anyone know off hand what the replacement bulb would be?

In advance, Thank You for your responses,

Greg W

[RJay]

Hi gwscuba,

The voltmeter you describe should be reading the voltage output from the alternator and should read about 14.5 VDC. Pulling the dimmer switch should have very little or no effect on the output. As a first step remove the dimmer switch and connect the two wires of the dimmer switch together effectively bypassing the dimmer and then check the voltmeter. Otherwise I would take voltage readings at the alternator and work back to the voltage regulator and check for the proper voltage.

[Snowman 1]

Inadequate gauge ground wire...call Monaco tech support.

[tquarles]

Monaco is also your source for an exact replacement for the headlight switch. I know it is a standard switch from someone else, but I'm pretty sure the $50 they charged me isn't much more than I remember paying for a ford switch for a car a few years back. I've got one for my 2002 sitting on the dash waiting for time to work on it - the dimmer rheostat failed and I have 2 gauge light levels - BRIGHT and off. Looks like an easy replacement as soon as I figure out how to get the knob off the end of the shaft without breaking the switch in the process - everything plugs in to sockets on the switch.

[Robi.1014]

My dash volt-meter acts similarly: when headlights are turned on, the volt-meter changes its reading to a lower value. "Snowman1" (above) has confirmed what I assumed what was happening.

But rather than fix the problem, I wanted more. I wanted to read both "chassis" and "house" volt-values at the dash area (my Diplomat has a digital-meter feature in the bath area). So I installed two expanded-scale (analog) DC volt meters just above the Allison transmission-control panel....held in place with Velcro. For the voltage-feed to the meters, I tapped into locations where I knew that voltage-drops would not affect my readings. It's a hoot to see the starter batteries labor to start the main engine...and how they labor less when "Battery Boost" is selected.

[tomgagne]

headlight switch Here is a link with the information you need. Grounding problems are common with Monaco

[Snowman 1]

The too small gauge wire affected more than just the voltage reading on our coach. When the headlight switch was pulled out, the temp gauge would jump about 20 degrees higher and subsequently would activate a low coolant light on the dash. Could never understand why the coach would run hotter at night until we put two and two together.

During one of our annual pilgrimages to the Monaco service center we had this problem corrected by their techs. Took him all of ten minutes to correct. All is well now. No RV center or truck shop we went to was able to properly diagnose this electrical gremlin until we took the coach to Monaco. I suspect this is your issue. Good luck.

[Rex]

Greg, first sounds like you have one or more bad Grounds. Monaco is known for this. On my coach all the instrument gauges are daisy chained to a common ground. Even if the ground itself is good, the daisy chain can be broken by just one loose connection on back of one gauge.

As for the headlight switch, you can get that at Advanced Auto stores, or any auto parts store. For Advanced, the part # is 5970857 for 1973 Chevy C10 truck. The switch is an AC Delco D1588, about $17.

[gwscuba]

As I expected I was granted a wealth of information that will help me solve the dash problem.

I'll tackle the issues this weekend.

Thanks Everyone for your fast response !!!

Greg W.

[Rex]

Well besides the part number, here is the rest of the story so to speak. Getting the headlight switch out.

• Headlight switch.
• This is tricky.
• The shaft comes out but there is a catch.
• There is a spring loaded small ‘ tit ’ under the bottom of the switch near the back.
• This must be pressed hard while you pull the shaft. It is stubborn and may take several tries to get it out.
• Now unscrew the mounting that surrounded the shaft on the front of the dash.
• Slip the removed mount on the shaft and set them aside.
• The switch is now off the back of the dash.

[HarveyP]

Rex is correct about the release button for the switch knob being on the bottom side of the switch. If you can remove your switch, take it to an auto parts store. Autozone had a book with pictures. My 94 motorhome had a switch the same as a 1970-something Ford pickup truck. Under $20 to replace. Good luck, HarveyP

[observer]

I had a '02 Endeavor. The following was the PN for the headlight switch.
Hd.Lt.Sw -Sorensen LS62

[Jocat54]

I guess I have a grounding problem also. We are on the last leg home from a 5000+ mile trip to Maine from Texas--noticed when I turned the headlights on the temp would start climbing (up to about 200-210) first time it happened I pulled into a rest stop to check things out and as soon as I turned the headlights off the temp went back to normal. Guess I will be trying to find the ground for the dash when I get home.


I also replaced the headlight switch a while back Wells part#141--think it was for a 1973 chevelle about $18.

John