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Author Topic: dim headlights 1978 MCI converted to 4 headlight system  (Read 2184 times)
farmallrick
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« on: August 17, 2013, 07:48:46 PM »

Hi New member Easley SC Just bought a 1978 MCI that has been converted by a gentleman from Mississippi He did a great job in my opinion. We have really enjoyed the coach so far. I have been doing some gen. maint. lights etc. I feel the headlights are dim, it has been converted to a 4 rectangle headlight system. I have installed all new headlights ( blue light) that seemed to help some, any ideas? Coach runs great (8V71) about 22k on overhaul according to paperwork. Allison Auto Trans seems to shift fine min. leaks on engine and trans. uses about 1 gal SAE #40 wt  about every 1000 miles witch is par for this engine I believe. Now working on getting dash lights to work side dash/switch lights working fine. Only the headlights seem dim more so  on high beam setting any ideas. I have replaced the main Batteries with new ones like the coach called for. Thanks Rick Sundblad Easley SC 
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wildbob24
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« Reply #1 on: August 17, 2013, 10:16:01 PM »

Rick,

Welcome aboard.

In my experience, dim headlights can usually be traced to bad grounds. Another possible culprit would be the floor mounted dimmer switch.

Keep an eye out in the calendar section here. Periodically, some local busnuts hold rallys at Palmetto Cove campground, near Cleveland SC. Very close to you. I would be a good place to meet some like minded folks.

Bob
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P8M4905A-1308, 8V71 w/V730
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« Reply #2 on: August 18, 2013, 04:12:46 AM »

   I've found the blue light didn't illuminate as well as regular. Take a voltmeter and check the voltage at the headlamp plugs. If it is ok, the Sylvania Silverstar, or Silverstar ultras are quite good. The ultras have a shorter lifespan than the other, which is shorter than a regular headlamp. They also cost more than regular lamps. Of course, these are 12 volt models.
   I don't know how they will hold up from road shock in a coach though.
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« Reply #3 on: August 18, 2013, 06:06:41 AM »

First, I would verify that the headlight sockets are hooked up properly. It's easy to get the wires connected wrong.

It's possible the 78 might have come from the factory with 12 volt bulbs, in which case they would be wired in series with a center tap to 12 volts. I think they started this wiring
in the late 78 models. If that's the case, then it might be that the previous owner changed the power feed to 12 volts, which will result in only 6 volts to each headlight
and therefore a very weak output. Although I really doubt this is the case, you definitely should test the voltage at each headlight.

Then, if the voltage is correct, then check grounds and wire and connections for corrosion. Also, make sure the wires are properly sized for 12v bulbs.

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Craig Shepard
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« Reply #4 on: August 18, 2013, 06:19:27 AM »

Be sure to check the voltage with the bulbs connected.
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farmallrick
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« Reply #5 on: October 14, 2013, 05:56:27 PM »

Sorry it took me so long to get back been busy Thanks for the help Im betting on the dimmer switch I about have to stand on it to get it to from bright to dim etc. and i weight a good 250 LOL  Also checking ground and voltage this weekend when I get back to the project. Inside the coach it has a tag that says headlights are a 12 volt system so I think you are correct on that part!! I feel a bad ground/ dimmer switch may be the gremlin!! Thanks Again Rick Sundblad  I'll keep an eye out for the deal in Cleveland SC !!!
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gumpy
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« Reply #6 on: October 14, 2013, 08:06:42 PM »

Sorry it took me so long to get back been busy Thanks for the help Im betting on the dimmer switch I about have to stand on it to get it to from bright to dim etc. and i weight a good 250 LOL  Also checking ground and voltage this weekend when I get back to the project. Inside the coach it has a tag that says headlights are a 12 volt system so I think you are correct on that part!! I feel a bad ground/ dimmer switch may be the gremlin!! Thanks Again Rick Sundblad  I'll keep an eye out for the deal in Cleveland SC !!!

Yeah, probably not the dimmer switch. In a properly wired 12v system, the dimmer switch only controls a relay coil. Could be relay contacts, but most likely either improperly wired sockets or bad grounds.
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Craig Shepard
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bevans6
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« Reply #7 on: October 15, 2013, 03:58:36 AM »

Just a possibility - my similar vintage MCI has a Universal Coach Parts (Universal Coach Parts was owned by MCI and is now called MCI Service Parts) conversion kit installed that was an MCI-sold solution for 12V headlights.  My 1980 MC-5C came factory with 24V headlamps.  The conversion is a black box maybe 4" by 6" by 1" deep that converters 24V to 12V, one for each side, and the lamps are pretty dim.  I went to Hella halogen lamps without much improvement, but I haven't investigated further yet.

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
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« Reply #8 on: October 15, 2013, 05:26:48 AM »

1978 was the year MCI started installing 12v headlights. Near the end of the year. Depending on the serial number, his bus could have factory 12v headlight,
or it could have been converted. MCI issued a bulletin on converting from 24v to 12v.

The sockets on the rectangular bulbs are not wired the same as the round bulbs, and it's not obvious, so it's possible that whoever did the conversion
to rectangular simply wired them up like the round bulbs. It seems to me that when I did that on a friend's bus, because I didn't know better and didn't
have directions with the rectangular bulbs, they were pretty dim.

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Craig Shepard
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Bill B /bus
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« Reply #9 on: October 15, 2013, 10:18:59 AM »

If you have 12V lights then connect via a 24 coil relay to the 12V system supply. Wire that through the old style dimmer switch, no relays just switch for hi/lo, then to the headlight wiring. Simple, cost effective solution. Gits rid of balance line and two relays.
Works successfully on two MCI's, an 85 and 86.

Bill
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« Reply #10 on: October 15, 2013, 11:36:38 AM »

I was going to do that, but the OEM 12V system supply on my 1980 bus is fused at 30 amps.  I didn't think that was enough to run headlights reliably but it probably is just fine if you stay away from the high wattage lights.  I may try it from my Vanner now that I have reconfigured and would have up to 60 amps at 12v available. 

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Spicer 8844 4 speed Zen meditation device
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Nineforever
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« Reply #11 on: October 15, 2013, 06:09:02 PM »

I went with speaker LED excellent lights there available in the round 4 head light system  or the retengular 4 head light set up ..    excellent in this north country with all the wildlife on the roads .
The LED are exspensive but well worth the money .. there is some knock offs on the market much cheaper but not near the quality . The LED use far less power to run .
Dave
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Hyway 3 100 klms south of Yellowknife NWT Canada
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« Reply #12 on: October 15, 2013, 07:22:54 PM »

If you have 12V lights then connect via a 24 coil relay to the 12V system supply. Wire that through the old style dimmer switch, no relays just switch for hi/lo, then to the headlight wiring. Simple, cost effective solution. Gits rid of balance line and two relays.
Works successfully on two MCI's, an 85 and 86.

Bill


That's a great way to ruin two very expensive batteries.
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Craig Shepard
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farmallrick
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« Reply #13 on: October 15, 2013, 08:11:28 PM »

OK Grumpy from minn How do you properly wire up the sockets for rec. headlights I'm sure this guy just wired them the same I would have HELP thanks Rick Sundblad  Easley SC
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RJ
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« Reply #14 on: October 15, 2013, 10:30:19 PM »

Rick -

If you do a search for "MCI Headlight schematic" on this site, over on BNO (busnut.com), or Google, you should come up with the proper wiring diagram for running 12v headlamps on your 24v system coach.

When you study it, it looks weird and "that'll never work," but it does, and does reliably.

Another reason your headlights are dim is simply because they're the rectangular style.  It's been shown in various places that the light output from rectangulars is inferior to round lamps, simply because of optical physics.  Oh, sure, they may "look nice" and more "modern," but when it comes to safety, they're worse.  IMHO, you'd be better off pulling the current lights and going back to the OEM round units and wiring them properly.

If you are going to be doing a lot of night driving, the very BEST headlamp set-up is European-code Cibie halogens, as opposed to the poor output US DOT lights.  E-codes have a very sharp cut-off to the left to prevent glare to on-coming traffic, with a corresponding increase down the RH side of the road.  Stock E-codes will illuminate a stop sign on a rural road at night nearly 1/2 mile away, and over a mile away on high beam.  Not cheap - about $300 for a four-headlamp installation, but what price SAFETY??

Finally, since you're a newbie here, welcome aboard!  Please take a couple minutes to edit your profile to include a signature line, similar to mine below, that will automatically show up with each of your posts.  Simply click on the "Profile" tab above, then, in the LH menu, click on "Forum Profile Info" and follow the prompts.  By doing so, we'll be better able to help direct you to parts & service sources in your neighborhood, and as a bonus, you might just discover that there's another busnut nearby!

FWIW & HTH. . .

 Wink
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RJ Long
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« Reply #15 on: October 16, 2013, 07:32:19 AM »

RJ, I looked up mci headlight schematic, on bno search, it didn't come up, is there another way to get to the schematic? Thanks, tom, lvmci...
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« Reply #16 on: October 16, 2013, 12:04:38 PM »

The later MC-9 manual section for electrics is here:  http://www.buses101.com/PDF_Files/MCI%209%20Maint%20Manual%20in%20PDF%20format/MC-9%20-%20Maint%20Manual%20Section%207.pdf

If you go through to the schematics, the first one is exterior lighting.  The headlights are on the left and bottom of the page.  What you see is pretty complicated and I would not try to duplicate it without a serious reason why.  

Here is a walk-through of the head lamp control circuitry.  It starts with the batteries, which feed a 12v connection from the center terminal of the battery pair to a headlight cut-off relay in the AC junction box (ceiling of the front luggage bay, driver's side).  That relay is the on/off relay and is controlled by the headlight switch - switch on, and it feeds 12V power to the junction box headlight relay in the front electrical bay beside the driver.  That relay is controlled by the dimmer switch.  The left hand pair of headlamps takes 12V power from the junction box headlight relay (low beam is on by default if the headlamps are switched on, and the relay switches low beam off and high beams on when it is controlled on by the dimmer switch) and goes through a pair of diodes to prevent back feeding to the 24V power stud #28 (stud #28 provides all power for the headlamps circuits).  This means that the left set of headlamps is getting 12V power between 24V and 12V on the batteries.  The junction box headlamp relay also sends 12V power to the right hand headlamps in the same fashion as to the left hand set (low beams always on by default, relay controlled on will turn low beams off and high beams on) except that the right hand headlights are grounded to complete the 12V circuit.  There are some things that I don't get, at first glance, about this circuit - it goes through a 15A breaker in the AC junction box, then a 10A breaker in the front junction box.  The feed from 24V for the left headlamps goes through a pair of diodes, which should drop the voltage to them by 0.7V and make them a tad dimmer than the right hand side headlamps.

The issues with converting with this scheme that I see (without going out to my bus to check) is that there is no headlamp relay in the AC junction box to take the 12V feed from the batteries, the wiring from the AC box relay to the junction box headlight relay would have to be added, and there is a bunch of wiring and a stud terminal strip in the front electrical bay that may have to be added.  A lot simpler to just grab the 12V from the stud in the junction bay and substitute it for the 24V feed on the existing headlamp relay, but then you need a Vanner to equalize the batteries.  Anyway, for those who were ever curious about how the later MCI system works, this is it.

Brian
« Last Edit: October 16, 2013, 12:18:55 PM by bevans6 » Logged

1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Spicer 8844 4 speed Zen meditation device
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« Reply #17 on: October 16, 2013, 07:23:03 PM »

Bill B/bus, Could we get a little more info on the way you wired your other buses. Did you fuse the 12v. power and if so what size fuse. Also what size 24v. relay. I have a c3 that the lts are all screwed up and like your simple system. I don't see any way you could hurt your batts. if fused right. How do you know which of the terminals are grd. or high or low on the headlights?

Thanks Richard
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bevans6
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« Reply #18 on: October 17, 2013, 03:32:05 AM »

Fusing has nothing to do with hurting batteries.  You hurt the batteries if you pull a sizable load (like headlights) from the 12V center-tap without balancing the load on the 24V tap.  Over time the lower battery gets under-charged, the upper battery gets over-charged.  The question is how bad is it - we know it's bad, but is it a beer at lunch bad, or a bottle a night bad?  If you have a Vanner or other equalizer it will accommodate the load difference and you will be perfectly fine.  If your bus is like mine there is a 12V stud on the panel in the main electrical bay, stud 55 from memory.  That is fed from a center tap with a 30 amp fuse on a 10 gauge wire.  That is ample for four standard 55 watt headlamps if you aren't using that tap for anything else.  I was using mine for trailer brakes, which are also a high amp draw, which is why I didn't use it for headlamps.

Edit:  Just went and got my MC-5C schematic for it's 24V headlamps.  The wires to the headlamps are 14 Ga which should be fused at 15 amps which would support 200 watts of lights for each of the high beam and low beam circuits.  I think my headlamps are 60 watts for the low beams and 55/55 for the high beams, so the maximum load would be 220 watts when the high beams are on, which is overloading the 14 gauge wire and the voltage drop would be significant (around 6% I think, to the RH headlamps).  The most simple way to get 12V to the headlamps with minimal changes to wiring would be to remove the wire from the common pole of the dimmer switch to the load side of the headlamp relay (leave the 24v wire from the switched side of the dimmer switch that goes to the coil side of the relay, it is what switches the relay) and connect the load side of the relay to 12V at stud 55 through a new switch.   This would get you your 12V headlamps but would be overloading the fuses and some of the stock wiring (the 14 Ga wire that feeds both the sets of high beams).  The other way to do it would be to put a 4 relays in close to the headlamps and use the stock 24V feed to switch them, and feed the load side with 12V with 10 gauge wire from the 12V stud or directly from the batteries.  The 12V stud #55 in the front junction box is fed with 10 gauge wire and a 30 amp fuse.  If you do either method I recommend removing the 12 ohm pre-heater resistor at the headlamp relay, it's not needed with modern headlamps at all.

Brian
« Last Edit: October 17, 2013, 04:55:56 AM by bevans6 » Logged

1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Spicer 8844 4 speed Zen meditation device
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1972 NTM MK-4 B/SR
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« Reply #19 on: October 17, 2013, 05:00:36 AM »

Just to explain why I am so into this, my winter project is to replace all my clearance/marker lights with 12V LED lights, so I have be designing the modifications to the stock wiring to let me do that as cleanly as possible.  As a result of this thread and the research I have done, the project now includes 12V headlights!  Nice synergy.

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Spicer 8844 4 speed Zen meditation device
Vintage race cars -
1978 Lola T440 Formula Ford
1972 NTM MK-4 B/SR
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« Reply #20 on: October 17, 2013, 05:09:24 AM »

Thanks grumpy being a transplant from nw Iowa I was about ready to go to tractor supply and buy me a light bar to mount under the bumper or on top of the coach with about 6 field lights on it that would light up the world lol
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gumpy
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« Reply #21 on: October 17, 2013, 05:17:33 AM »


The issues with converting with this scheme that I see (without going out to my bus to check) is that there is no headlamp relay in the AC junction box to take the 12V feed from the batteries, the wiring from the AC box relay to the junction box headlight relay would have to be added, and there is a bunch of wiring and a stud terminal strip in the front electrical bay that may have to be added.  A lot simpler to just grab the 12V from the stud in the junction bay and substitute it for the 24V feed on the existing headlamp relay, but then you need a Vanner to equalize the batteries.  Anyway, for those who were ever curious about how the later MCI system works, this is it.

Brian

Yeah, that 12v stud in the front junction box is rated at 10 amp. Not gonna run a set of headlights for very long.

There are many reasons why MCI chose to wire 12v headlights up the way they did in the schematic shown.
« Last Edit: October 17, 2013, 05:21:48 AM by gumpy » Logged

Craig Shepard
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« Reply #22 on: October 17, 2013, 10:57:13 AM »

I couldn't let this go - something was bugging the heck out of me and I couldn't put my finger on it.  Then I got it - how does MCI get away with only a 10 amp breaker in the 12V feed to the headlamps?  I figured a 15 amp fuse would be minimum and I would use wiring and fuse for 20 amps.  Then I realized the MCI system was actually a 24 volt system with the headlamps in series, not in parallel like a normal 12 volt system would have.  The 12 volt tap, with all it's complex relays, four fuses, and so on - is only there so that if one headlamp fails the other one still has a path to power and can work on it's own.  So the maximum current under normal circumstances in the 12V tap to the batteries is effectively zero, and goes up to around 7.5 amps if one side has failed and the other side has high beams on.  Gumpy is dead right - there is a reason MCI did it that way!

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Spicer 8844 4 speed Zen meditation device
Vintage race cars -
1978 Lola T440 Formula Ford
1972 NTM MK-4 B/SR
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« Reply #23 on: October 17, 2013, 07:04:48 PM »

Gumpy is dead right - there is a reason MCI did it that way!

Sometimes it's pretty hard to second-guess the factory, eh?

 Grin
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RJ Long
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« Reply #24 on: October 18, 2013, 06:21:23 PM »

As I also have a 12 volt system installed  and such I went the 24 volt relay route and wired up the 12 volt lights. Works great.
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« Reply #25 on: October 18, 2013, 07:51:59 PM »

I couldn't let this go - something was bugging the heck out of me and I couldn't put my finger on it.  Then I got it - how does MCI get away with only a 10 amp breaker in the 12V feed to the headlamps?  I figured a 15 amp fuse would be minimum and I would use wiring and fuse for 20 amps.  Then I realized the MCI system was actually a 24 volt system with the headlamps in series, not in parallel like a normal 12 volt system would have.  The 12 volt tap, with all it's complex relays, four fuses, and so on - is only there so that if one headlamp fails the other one still has a path to power and can work on it's own.  So the maximum current under normal circumstances in the 12V tap to the batteries is effectively zero, and goes up to around 7.5 amps if one side has failed and the other side has high beams on.  Gumpy is dead right - there is a reason MCI did it that way!

Brian

I would say you are just now starting to understand the wiring of the MCI headlights. Study it for a few more weeks before you go trying to change your bus. It's kind of important that you fully understand all the little intricacies of this wiring schematic before you start "improving" on it or even before you decide to convert to it.
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Craig Shepard
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