| Author | Message | ||
| Grant Thiessen (Busshawg)
Registered Member Username: Busshawg Post Number: 142 Registered: 10-2007 Posted From: 206.45.93.160  Rating: N/A |
My headlights frigged up on me last night. I'm thinking it's a ground but would liek some imput. The passenger side seems to be working alright however the drivers side when on dim both lights are on. The bright is getting full voltage and the dim is only getting 4 or 5 Volts. When on bright only the bright one is on and looks good but the other is out. Any ideas?? Thanks | ||
| Ralph Peters (Ralph7)
Registered Member Username: Ralph7 Post Number: 8 Registered: 3-2004 Posted From: 66.59.120.99 Rating: N/A |
I rewired my mc-8 to 12V, which ment rewire the dimmer switch, it's not hard. I only use 2 for low& 2 for hi, but I use all 12V h/l 3 terminal bulbs. Used my house 12v for power. Hope you have the wire diagrams, cause you may have 24-12, to me is a pain when not working properly. You may have a blown bulb, bad ground, broken wire. Do you know how many mods have been done, mine had cut or disconnected wires. Diodes mount rusted etc. | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 816 Registered: 8-2006 Posted From: 64.55.111.6 Rating: N/A |
Grant, Lack of a ground is probably your problem. (If your lights are still factory 24 Volt.) The ground side of the high and low beam filaments are connected in the outside headlight. If the ground opens on the outside bulb, there is still a circuit to ground thru the inside (high beam) filament, and the outside high filament, which is why the lights are all on dim on low beam. Try using your voltmeter between the ground spade terminal at the outside bulb, with the lights on low, and a good chassis ground. If you find voltage, you've found your problem. About the same scenario if its factory center tap, or the schematic I published a while back. If the PO has "seriesed" 12V bulbs, go down to the sporting goods store, and buy a hunting license! HTH, George | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 817 Registered: 8-2006 Posted From: 64.55.111.6 Rating: N/A |
Only a couple of things wrong with doing it as suggested inbetween above. 1. The focus is different between dual and single filament bulbs, which is why they were made in the first place. The inside, or high only beam is designed to throw light much farther out in a smaller pattern, while the outside bulbs fill in the shorter distance and the sides. That configuration looks like lots of light right in front of the bus, but there isn't much farther out where you need it on high beam. 2. When one high beam burns out, you have one light left on instead of three... ? G | ||
| Grant Thiessen (Busshawg)
Registered Member Username: Busshawg Post Number: 143 Registered: 10-2007 Posted From: 206.45.93.160 Rating: N/A |
I thought my bus had 12V head lights, quiet sure it does. However when I use my volt meter grounding to the bus instead of the wire I get 24 V , when I use both the wires with teh volt meter I get 12V , this is on the high beam only as I can't get much out of my low beam at all. This is baffling me, but then again that doesn''t take much, haha. I will rewire the pods with new plugs tonight and see if this helps. The PO has rewired within the POD already and it maybe just a simply connection problem as they were working very well up till last night. | ||
| Mark Renner (Boomer)
Registered Member Username: Boomer Post Number: 163 Registered: 11-2006 Posted From: 206.58.200.38  Rating: N/A |
MCI had a service bulletin on the correct way to convert to a 12V lamp system on 8's and 9's. You can request it from their service department. | ||
| Grant Thiessen (Busshawg)
Registered Member Username: Busshawg Post Number: 144 Registered: 10-2007 Posted From: 206.45.93.160 Rating: N/A |
I can see how your suggestion will work Ralph but if it's just a ground I would prefer to keep it this way, less off of the house batteries. I also think you right on track George, I don't have a wiring diagram but it shoudln't be too hard to figure out the ground colors. The PO has the red wire connected wih shrink tube to both lights. I'll play more tonight if it doesn't snow, getting cold up here again. | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 818 Registered: 8-2006 Posted From: 64.55.111.6 Rating: N/A |
Grant, Appreciate your sense of humor! There is a lady named Helen Hunt who knows just what's wrong. Figure that one out? If you are getting 24V to ground from a hot terminal, the bulbs are either 24V, or an improper rewire has ocurred. 12V headlights in series on a 24V bus can't be done properly, period. The outside bulbs have three terminals, because the ground side of the filaments are connected inside the bulb. So, when you take the ground off of the right outside bulb, which do you hook it up to on the left? The high or the low? The inside, or high only can be done, the only problem with doing it this way is you don't get the proper light on low beam, and a failure of one causes instant darkness. So, the proper solution is the center tap, done correctly. This leaves the power provided by the chassis system, doesn't abuse batteries, and doesn't cause any other bulbs to go out when one fails. Also doesn't need a wire or circuit breaker re-size. As Mark says, there is a bulletin from MCI on how to do it, the only thing wrong with it is that it is really complicated, for no reason that I can see. Thinking further, you will read 24V to chassis ground from one side of center tapped headlights, but only 12V across good bulbs, and 12V to ground on the other side. At this point, check your bulb numbers please. Lets find out if they are 12 or 24 first. While you are at it, pull the plugs, and put the meter on an Ohms setting, maybe RX1, or the lowest Ohm scale, 0-200, and read across the filaments on the left side. You should read a few Ohms on a good filament, and open circuit on a bad one. The high beam will read an Ohm or so less than the low beam. Good luck, G | ||
| Mark Renner (Boomer)
Registered Member Username: Boomer Post Number: 164 Registered: 11-2006 Posted From: 206.58.200.38 Rating: N/A |
You could also replace the plugs and headlight buckets if you haven't done so already. All the old buses I have worked on, these pieces were shot. Cheap to replace 'em. | ||
| Grant Thiessen (Busshawg)
Registered Member Username: Busshawg Post Number: 145 Registered: 10-2007 Posted From: 206.45.93.160 Rating: N/A |
Thanks guys, I will see how far I get with it tonight, kind of think I should maybe just leave it, so nothing else goes wrong! Will let you know in the am how I made out. | ||
| JR Lynch (Njt5047)
Registered Member Username: Njt5047 Post Number: 265 Registered: 7-2006 Posted From: 71.75.10.27 Rating: N/A |
If you have an equalizer, I'd convert those puppies (headlights only) to 'real' 12V. Just like 100% of OTR trucks. Used equalizers are not too expensive and easy to install. An equalizer is useful if you're using the rear OEM battery for a house battery. Without an equalizer, the batteries don't charge equally when one is very low. The 'conversion' would follow correcting any rusted buckets and ancient plugs and wiring. You probably have 12V headlight bulbs. But they are wired in series so that 24V will power both. Thru a complicated system of diodes (located beneath the drives floor) and relays, if one headlight fails, the failure is sensed and 12V is applied to the remaining headlight filament--one hopes. You may wish to verify that the 12V backup headlight lead is correctly connected to the center battery posts (12V). That lead is the 12V backup source. If it is improperly attached to the 24V post, it will promptly blow out whatever headlight remains if the 24V system fails. Good luck on sorting out that system if it isn't some simple thing like a rusted ground (RH headlight) or plugs. A right good many MCIs have been cobbled up by previous attempts to repair the 24/12V system. An equalizer will easily compensate for the unbalanced 12V load on the rear battery without taxing the system. National Bus Trader had a good article covering dx and repair of your headlight system. If you could get a copy, it would make restoration of the OEM system easier. NBT could perhaps do a search and sell a copy with that article. Or reprint the article. I'm old and about blind at night. So don't drive much at night, but, while my MC9 headlights work fine for now, if they take a dump, they'll be converted to 12V so fast. I've already go most of the wiring in place and a Century Class steering column with a dimming turn signal stalk. Looking forward to their failure! Apologies for the long post. Good luck! JR | ||
| Mark Renner (Boomer)
Registered Member Username: Boomer Post Number: 165 Registered: 11-2006 Posted From: 206.58.200.38 Rating: N/A |
JR has pretty well covered it. One time we spent the better part of two days trying to keep headlights from blowing on an MC-9 that a prior owner had "converted". After several calls to Richard Olsonawlski, long time MCI service rep, and reading the service bulletin, we finally got it figured out. MCI really hatched a rube goldberg system with that one. | ||
| Grant Thiessen (Busshawg)
Registered Member Username: Busshawg Post Number: 146 Registered: 10-2007 Posted From: 206.45.93.160 Rating: N/A |
Lots of great advice, that is so much appreiciated! My headlighs have been working very well up to this point, so I feel that IF I can find the problem I will just fix it the way it was for now, as I really do need to understand this system before I make any changes. The lights were working good so it must be a connection problem somewhere. I installed a new pigtail last night and re-did my connections in the head light pod, no changes. Gumpy had mentioned the connection strips, so I located one infront of the dimmer swtich just above the pod that looked quite corroded. I am in the process of cleaning it up and installing new nuts etc. , I have a feeling this could be my problem, but as many of you have mentioned and from some experience with my old John Deere 24V tractor, it might not be just that simple. | ||
| JR Lynch (Njt5047)
Registered Member Username: Njt5047 Post Number: 267 Registered: 7-2006 Posted From: 71.75.10.27 Rating: N/A |
Grant, if you don't find your problem, you might try swapping the headlight relays out with any other relay. You could have a bad relay. They'll interchange. Relay failure is rare, but...? Easy to rule out. FWIW, the dimmer switch just toggles the relays. Shouldn't cause failure beyond not winking up and down. Keep in mind that you may have two layers of failure...the 24V system will fail and will then be backed up by the 12V system. You may have been driving on the 12V system for a bit. Probe the headlight relay output for 24V. If you have that, the problem is downstream from the relays, if you don't have 24V output at the relay, and replacing the relay doesn't fix that...bummer. Check circuit breaker. JR | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1583 Registered: 12-2000 Posted From: 76.66.19.195  Rating: N/A |
Often the headlight wiring is a bit of a mess by the time we own our coaches. Another excellent preventive maintenance project is a re-wire and refresh of the headlight wiring/relays and dimmer switch. For those of us still running 24 volt bulbs, a 12 volt conversion opens so many doors for improved lighting options from the plain sealed beam 24 volt peepers. The biggest issue is not the strategy you choose, or the nuts and bolts choices that your coach is equipped with, but whether the wiring and components are in a state of good repair. happy coaching! buswarrior | ||
| Grant Thiessen (Busshawg)
Registered Member Username: Busshawg Post Number: 149 Registered: 10-2007 Posted From: 206.45.93.160 Rating: N/A |
There working, not sure what I did, haha. Cleaned passenger side ground, cleaned and replaced nuts on the drivers side connection strip , replaced one pigtail and re did all of the connections in the headlight pod, replaced the center tap termial on the battery and then checked with my voltmeter. IT works!! Hi and low, plugged in my headlights and sure enough, all screwed up again, swore a little , well maybe a lot, took a step back had a break. Started playing and testing differnt head lights and finally it works!! Was it the headlight all along? I kind of think so. However it is working. Thanks for all of your help! | ||
| JR Lynch (Njt5047)
Registered Member Username: Njt5047 Post Number: 268 Registered: 7-2006 Posted From: 71.75.10.27 Rating: N/A |
Now. Remove the 12V feed from the center battery tap while the headlights are 'ON'...they should remain lit. This challenge will indicate that the 24V function is working. Then reattach the 12V tap and remove one working headlight from the circuit (pull the plug off of either headlight)and verify that the remaining headlight continues to illuminate. It obviously should. Then you'll know that your system is functioning correctly. Apologies in advance! JR | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1597 Registered: 12-2000 Posted From: 76.66.16.242 Rating: N/A |
JR has it nailed. Good test. happy coaching! buswarrior | ||
| Grant Thiessen (Busshawg)
Registered Member Username: Busshawg Post Number: 150 Registered: 10-2007 Posted From: 206.45.93.160 Rating: N/A |
Excellent , I will do this tonight Thanks guys | ||
| Len Silva (Lsilva)
Registered Member Username: Lsilva Post Number: 231 Registered: 12-2000 Posted From: 24.164.20.23  Rating: N/A |
See if this helps you figure it out. http://www.mcicoach.com/Parts-Service-Support/serinfo/serinfo07G.htm http://www.mcicoach.com/Parts-Service-Support/serinfo/serbull/1930.pdf |