| Author | Message | ||
| Nellie Wilson (Vivianellie)
Registered Member Username: Vivianellie Post Number: 5 Registered: 11-2008 Posted From: 70.52.105.56 Rating: N/A |
I’m new to this, so this may be a stupid question? Anyway, here goes… Back ground: My MCI-5C always had (since I got it, anyway) terrible lighting… at least compared to more modern vehicles. Even though the outside lamps (low-beams) had been replaced with halogens, I could barely see the road. And the lights always fluctuated. The inside lamps, supposedly the high beams – still the older style lamps – weren’t much better. So when one of them (the left high beam) quit working, I decided to replace both high beams with halogens (Warner 5001s). Well! Got glorious super bright illumination from the right high beam, but the left one still didn’t work. It looks like, to my untrained eye, some wiring to that lamp has disconnected from the dimmer switch. But last night, before I could figure things out, I had to move the bus out of this shop I’m using. And POP! A bright flash and my new (right side) halogen 5001 is history. I still have the low beams (and I mean LOW) but now the high beam indicator (the little blue light in the dashboard) stays constantly on. And the low beams fluctuate just as they always did. Okay, okay… I’m getting there. Is it possible I have a 24 V headlamp system on this 5C? I’ve always read they were 12V, but why else would a brand-new headlamp get zapped like that? Is it possible the high and low beams were previously reversed? I mean, is it for sure the high beams are the ‘inside’ lights’ and the lows are the ‘outside’ lights? I ask because I noticed the lamps have different designations: Two are labeled ‘1C1’ and two are labeled ‘2C1’ (as I recall, the two new high beams were the 1C1s – I’m not near the bus now, but I’ll go double-check this). And does anybody know if the lamp wires go directly to the dimmer switch, or is there some type of relay or fuse in-between the dimmer switch and the lamps? In case it matters: The bus (main) electrical system was apparently upgraded not so long ago… there is (what looks to be) a fairly new battery equalizer, and I’ve just recently installed two new 8Ds. But the wiring to the horns, lights, etc. (in the lowest bin, driver’s side) is pretty awful. I cleaned everything up (superficially) but connections, etc. are rusty and some loose wires are flopping around (probably from radios and such that were removed from the bus… but who knows?). Neither my MCI Parts Manual (pretty useless for stuff like this) nor my Operator’s Manual gives me any clue. And I don’t yet have DA BOOK (to quote FAST FRED). I think I’m in trouble! The simplest, most straight-forward system (headlamps!) on this huge rig, and I can’t sort it out. Thanks for any suggestions. Nellie Wilson | ||
| Luvrbus (Luvrbus)
Registered Member Username: Luvrbus Post Number: 584 Registered: 8-2006 Posted From: 74.33.35.55 Rating: N/A |
Nillie, the 5 is 24 volt unless somebody has changed it over if you have the round headlights more than likey it is still 24v good luck (Message edited by luvrbus on November 18, 2008) | ||
| Jack Conrad (Jackconrad)
Registered Member Username: Jackconrad Post Number: 875 Registered: 12-2000 Posted From: 71.54.29.215 Rating: N/A |
Could be either. The bus is a 24 volt system, but many have had the headlights re-configured to allow the use of 12 volt bulbs. First step is to check the voltage at the headlights with a volt meter. You really need a wiring schematic to sort things out. If the high beam indicator is staying on, it sounds like you have a faulty dimmer switch or some wiring problems. Jack (Message edited by JackConrad on November 18, 2008) (Message edited by JackConrad on November 18, 2008) (Message edited by JackConrad on November 18, 2008) | ||
| Grant Thiessen (Busshawg)
Registered Member Username: Busshawg Post Number: 64 Registered: 10-2007 Posted From: 206.45.93.160  Rating: N/A |
I had the same problem with a 24 volt tractor I have, same principle, 24v system 12 v lights. I ended up blowing 5 out of 6 lights. After going through everything , and I mean everything or so I thought. Batteries, regulator, altenator what I found was a bad ground. Bad grounds do very funny things. Some of my lights were dim and others super bright. Try running a ground strap or before you do that get a piece of wire and ground right from the battery. This will save you some work incase that is not teh problem, but I'm quite sure this will be your problem. If it is your problem it may also resolve other issues that are developing that you haven't noticed yet, such as bad batteries. Have fun Have fun | ||
| Len Silva (Lsilva)
Registered Member Username: Lsilva Post Number: 176 Registered: 12-2000 Posted From: 71.99.25.84 Rating: N/A |
GROUNDS, GROUNDS, GROUNDS! Almost every time you experience "strange" happenings in an electrical system, it is due to a problem with grounds. Many times they are counter-intuitive. I don't know about your 5C but my 4104 had a heavy (4/0?) ground cable that ran the length of the bus and terminated in every junction box. Depending on the old corroded steel chassis of these rigs for return ground is problematic. | ||
| Nellie Wilson (Vivianellie)
Registered Member Username: Vivianellie Post Number: 6 Registered: 11-2008 Posted From: 76.64.243.178 Rating: N/A |
Man oh Man! (How long ago since you last heard that phrase?) You guys are SENSATIONAL... soon as I can get back into that shop (it's pissing snow right now) I'll start prodding and pulling (and praying) with your thoughts firmly in mind. All else fails, I'll drive the old gal down the mountain to one of our local backyard mechanics -with your thoughts PRINTED OUT before he touches my old Sally. Thanks so much and please keep your ideas coming. PS. I'm pretty desperate to get outta here... I can always drive on the low beams, I guess, but what a bummer. Nellie Wilson | ||
| Fred Nelken (Faster_freddie)
Registered Member Username: Faster_freddie Post Number: 41 Registered: 1-2005 Posted From: 75.214.24.236 Rating: N/A |
We had a 5A and the headlights were 24v. I had to have them changed to 12v so replacement headlights were easier to get. If your 5C does have 12 volt headlights, there should be a tag riveted on the switch panel under the drivers window that states the headlights are 12v from the factory. I don't think MCI started making the headlights 12v until the late MC7 or MC8. | ||
| Don Evans (Doninwa)
Registered Member Username: Doninwa Post Number: 153 Registered: 1-2007 Posted From: 208.81.157.90 Rating: N/A |
If it has been converted to 12V with a lead to the center tap of the batteries you want to be careful what you ground. Here is a link to MCI info on converting. http://www.mcicoach.com/Parts-Service-Support/serinfo/serinfo07G.htm If you want to use a clip lead to test grounds a fuse in the test lead will keep the smoke where it is suppose to be. Just needs to be heavy enough to carry the current for the headlights. Good luck Don 4107 PS. If you check the voltage to the working low beams, it should tell you whether you are wired for 12 or 24 volts. (Message edited by doninwa on November 18, 2008) | ||
| Gus Causbie (Gusc)
Registered Member Username: Gusc Post Number: 777 Registered: 11-2005 Posted From: 208.54.200.228 Rating: N/A |
Don, Ground is no different for 12v or 24v, the only difference is in the Positive tap from one of the batteries. | ||
| Don Evans (Doninwa)
Registered Member Username: Doninwa Post Number: 154 Registered: 1-2007 Posted From: 208.81.157.90 Rating: N/A |
Gus In the center tapped setup each of the bulbs will be connected to the center tap and if you connect that lead to chassis ground, poof. There are just a lot of potential problems or ways to get confused trying to trouble shoot this circuit setup unless you pay close attention. Makes a difference where you 'ground' your meter ie chassis ground or the center tap. For instance, if the wiring to the center tap is bad it could appear that the bulbs are just in series. A likely problem since it is probably connected directly to the battery and associated corrosion. Another, if the bulb on the "high side" has the connection that is supposed to be connected to the center tap shorted to chassis as a test it now has 24V across it and poof, not to mention the potential for letting the smoke out of the center tap or blowing fuse/breaker. If the center tap is shorted to chassis ground through bad insulation or installation, the bulb on the high side will see 24V, poof again and the center tap will burn open or blow the fuse, and it should be fused, but the other bulb will work OK. As I said above, check the working low beams to see what you have and go from there. Cleaning connections is the place to start. Several things in the original post point to connection problems. Screwball grounds can be much more confusing that the B+ side. Throw in a center tap and it is easy to get off track. Good luck Don 4107 | ||
| David Dulmage (Daved)
Registered Member Username: Daved Post Number: 221 Registered: 12-2003 Posted From: 142.46.199.30  Rating: N/A |
Perhaps a silly question, but what was the voltage rating of the existing headlamps that were already installed before you had this problem? Dave D | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 539 Registered: 10-2006 Posted From: 69.19.14.20 Rating: N/A |
Sounds like the coach has an "equalizer", these get strange when one battery is older and weaker than the other. FF | ||
| Wec4104 (Wec4104)
Registered Member Username: Wec4104 Post Number: 4 Registered: 7-2008 Posted From: 68.46.66.57 Rating: N/A |
I subscribe to the theory that your bus started out with 24V headlights, but after some diddling by a previous owner to convert to 12V, you have resulting wiring gremlins. One way to use 12V bulbs in a 24V system (and I do not like this technique) is to wire them in series. Connect one terminal on bulb "A" to the positive 24V. Connect one terminal on bulb "B" to ground. Then connect together the two open terminals on bulbs "A" and "B". This will work okay using 12V bulbs, because wired in series each will have half of the 24V voltage drop in the circuit. I do NOT endorse this approach, since it works like a string of cheap Christmas tree lights. If one goes out both lights quit working. Imagine being on the highway when both headlights suddenly fail. What if the previous owner wired both the low and high beams to operate in this fashion, but never got around to swapping out the low beam bulbs? You could be sending your low beam bulbs 12V instead of 24, which would explain the low light output. For the high beam issue, suppose the two bulbs were changed over to 12V. However, there is a problem with the wire that connects bulb "A" to bulb "B". Instead of "A" getting it's ground through bulb "B", this wire makes a direct contact with ground. That would send 24V through the light that went "pop", while the other bulb gets no juice. | ||
| Gus Causbie (Gusc)
Registered Member Username: Gusc Post Number: 778 Registered: 11-2005 Posted From: 208.54.200.178 Rating: N/A |
Don, I can't really follow your reasoning? If you short any pos lead to ground you will have smoke and sparks no matter what the voltage. The bulbs may or may not burn out in that case. I have a 24v Army truck with all lights 12v by a center tap. I have no other grounds anywhere other than the chassis. Never have had the slightest problem with lights. High and low beams are the same electrically since they are normally both centrally fed through the hi/lo beam switch. It is unusual for both sides to go out at the same time even with a ground problem so that makes me think the problem is in the hi/lo beam switch - the only thing the two hi beams have in common unless there is also a separate ground wire. Some buses have these but not sure if all do. | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1393 Registered: 12-2000 Posted From: 76.68.135.25  Rating: N/A |
Hello all. There is absolutely nothing wrong with an MCI style 12/24 wiring for headlights, unless you don't understand how it works. In which case, stay away from the wiring! The use of the term center tap gets misunderstood. Center tapping to get a source of 12 volts will imbalance the batteries, and should be avoided. Centre tapping to provide a "neutral" for the MCI style 12 volt headlight install only sees power on it if a headlight blows out, otherwise the current runs in series from 24+ through both lights in series to ground. The headlight relay has to be a double pole, it switches the 24+ and the "neutral" center tap, otherwise one light will stay on! The "neutral" is connected between the two headlights, so if one burns out, the other headlight continues to get current via the "neutral" and is exposed to only 12 volts. The high beams may be set up in a duplicate fashion, double pole relay etc. Left and right side 4 lamps wired in parallel, side to side in series The dimmer switch switches the control power to the double pole relays. This works just like your house, most of your current flows from hot to hot, through the various loads in your house, only the imbalance runs on your neutral. Who can draw a nice schematic? If the previous owner was clueless, if the quality of work done to the coach wiring previously is suspect, then you have a crap shoot, no matter what wiring you have. And busnuts inherit a lot of crap when they get their coach from wherever it last tried to make someone money... happy coaching! buswarrior | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 618 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
Gus and Nellie, Maybe I can clarify what Don is saying? The center tap is the cable between the positive terminal of the grounded battery, and the negative terminal of the other battery. If you connect one headlight hot to the positive of the ungrounded batt, that headlight's ground to the center tap, the other headlight's hot to the center tap, and that headlight's ground to the chassis ground, through relays and switches of course, everything will work properly. One headlight has no effect on the other, AND you don't burn water out of one battery. Yes, you have to do that twice to get high and low beam 12V lights. Actually all it takes is two 24 Volt DC relays, to connect the center tap to the high and low beams on one side. The hots stay on the other side, along with one coil term of the relay. Ground the other relay coil term, and the grounds of the beams with the hots on them go to the center tap. 12V headlights with no adverse effects! Nellie's problem sounds like someone has installed resistors, which could cause the problem she describes when one bulb fails. We're just not clairvoyant enough to figure out what someone else has done wrong at this point. As mentioned above, series connections are not the answer, as both lights go out when one fails, NOT TO MENTION THAT THE GROUNDS OF BOTH FILAMENTS ARE COMMON!!!!! Somebody is going to say "you can do that with high beam only bulbs," and I agree, but nobody can make hi/lo bulbs work properly in series. IMNSHO Nellie needs to take her bus to an ELECTRICIAN, along with the factory schematic! A sign in a local shop: Labor rate $25.00/hr $30.00/hr if you watch $35.00/hr if you help $50.00/hr if you worked on it first. George PS: I started this before BW's post, but it ended up in after. A little problem in the semantics, center tapping for 12 Volts should read: Using the grounded 12V battery for 12V in a 24V system should be avoided,(see what I said about burning water out of one battery.) I still stick with what I said, headlight center tapping works fine when properly done, and with only two 24V single pole relays. I'll draw a schematic in the am when I'm awake. G (Message edited by George Mc6 on November 19, 2008) | ||
| Nellie Wilson (Vivianellie)
Registered Member Username: Vivianellie Post Number: 7 Registered: 11-2008 Posted From: 70.49.112.60  Rating: N/A |
Again, thanks to everyone for giving my little problem so much thoughtful attention. I'm absorbing every word, and will immediately: 1. Go out and purchase (or borrow) a voltmeter and 2. Run the numbers on the old lamps and see what they actually are (12V or 24V?) and 3. Check for that tag that "Faster Freddie' mentions. But as BusWarrior and WEC4104 point out, who can know what jerry-rigging took place before I inherited the bus? Anyway, all your responses have given me a place to start... checking the voltage requirements of the old lights against the votage FEEDING them should throw some light on the subject (Opps... that's dangerously close to a pun, isn't it?). And, George, if you get awake enough to draw that schematic, could you give me a look? I'll probably end up following your advice... taking this problem to a real electrician. But any info I can offer will probably be appreciated - and maybe save some unnecessary trial-and-error (read: money)? As for the center tap, it appears there probably WAS one, but the wires - still hanging loose in the battery compartment - have long since been cut and taped. I must say, I never considered this might be a problem - I purchased the new halogens from a truck place that SAID they'd cross-referenced the headlamp numbers. But considering some of the other 'work' they did, I've got my doubts. When I can supply more specific information, I'll probably start a new thread, if that's okay protocol here on BNO? Hey, I'm hoping my picture comes up when I post this. Just uploaded it today, so hope I haven't embarrassed myself too much. Thanks to all. Nellie Wilson | ||
| Don Evans (Doninwa)
Registered Member Username: Doninwa Post Number: 155 Registered: 1-2007 Posted From: 208.81.157.90 Rating: N/A |
Maybe we should stick to calling it what MCI does in their service bulletin, a "balance wire". See schematic at: http://www.mcicoach.com/Parts-Service-Support/serinfo/serinfo07G.htm Simple circuit on paper. I should have said it matters where you 'reference' your meter when testing instead of where you 'ground' it. For instance if you 'reference' your meter to chassis ground you will find 24V on one lead and 12V on the other lead of the lamp on the high side. If you instead use your meter to test the two leads of the high side lamp you will find 12V seemingly at the same place you got 24V in the test above. This is assuming it is wired according to MCI's service bulletin. If wired some other way then all bets are off until someone traces it out. The problem is we still are guessing how the 5 is wired. Only the owner or his technician can tell us. Don 4107 | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 619 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
Couldn't shrink the schematic, so I sent it to Ian. Hopefully he'll get to it in the morning. It is a whole lot simpler than the MCI service bulletin which Don has graciously posted. AND, he is exactly right about where to put the meter probes!!! You must read voltage ACROSS the individual headlight terminals, period. But I am afraid that you may still get 24V across an open (burned out) bulb. We just don't know what is there! See ya in the am! G | ||
| RJ Long (Rjlong)
Registered Member Username: Rjlong Post Number: 1444 Registered: 12-2000 Posted From: 67.181.166.160  Rating: N/A |
Nellie - Cute pic - are you really not much taller than the front turn signal lamps on your MCI, or is that one of your munchkins? Back to the topic at hand: First, looking at the link Don posted for MCI's service bulletin, it mentions this wiring change to 12v headlamps was made with unit 34901 of the MC-9 production run. So chances are good to excellent that your MC-5C probably was originally wired for 24v bulbs. Especially since the last MC-5Cs rolled off the production line in 1980, and MCI didn't make this change until the mid-80s. However, as you've found out, somebody may have come up with something different in the ensuing years. Another thing I noted at the bottom of the bulletin is that MCI has changed back to all 12V exterior lighting on their buses beginning in April of 1992. Wasn't aware of that, but it makes sense - hard to find a 24v bulb at Oh Dark Thirty when Mr Smokey insists you have taillights! That and probably enough pressure from fleet owners to reduce replacement part expense, since 24V are more costly. Another thought which comes to mind, and hasn't been mentioned yet, is to pick up a Vanner Equalizer (get one from Nick @ Nimco). One side ties into the 24v off the batteries, the other side gives you 12v for just about everything you need. Designed so that neither of the big 8Ds are drawn down by 12v more than the other. They're used quite extensively on transit buses, so Nick will have lots of used ones available. They're also pretty dependable, rarely do you hear of problems with them, provided they're wired correctly. As with anything else electrical, if you don't do it right, you'll let the smoke out! Once you get the wiring sorted out, then let's talk about the headlamps themselves. As many of the old-timers around BNO know, I've got a VERY strong opinion about US-spec lamps. LOL! FWIW & HTH. . .  | ||
| David Dulmage (Daved)
Registered Member Username: Daved Post Number: 222 Registered: 12-2003 Posted From: 142.46.199.30 Rating: N/A |
My 1976 MC-8 is wired for 12V headlamps. It's possible your MC-5 was converted to this system. DaveD (Message edited by DaveD on November 20, 2008) | ||
| Nellie Wilson (Vivianellie)
Registered Member Username: Vivianellie Post Number: 13 Registered: 11-2008 Posted From: 76.64.240.110 Rating: N/A |
Well, RJ, I'm kinda short but not THAT short. Actually, you can't tell from the photo, but the front of the bus is up on blocks - okay, not very big blocks, I admit, but a few inches... just enough so I could slide under and change a leaky airbag. Reminds me of what one of the truck mechanics said... he pokes his head in, looks around and says, "Wow, I never knew these things had five airbags." Of course, I bit, a trout to a fly. "Really?" sez I, totally confused and looking frantically around. "Where is it?" And he keeps right on looking at ME, big sh**eating grin plastered across his mug. Oh, well - so I'm not the strong silent type. Thank you for the input, and thanks Don for that schematic... a little complex for my pea brain but I'm now trying to reach an electician (yes, I've caved). I'm sure he can easily decipher it. As mentioned in my initial post, an equalizer is aready installed (a Vanner? I don't know, will have to check). But maybe it's not doing what it's supposed to do... RJ, I'll be most interested in your take on headlamps... sure don't want to go through this again. Hey, what does FWIW and HTH mean? Meantime, I'm waiting too get back in the shop (it's -8C out there today) to run some of the tests you guys suggested. Also hoping for George's schematic - he says it's a little simpler than the MCI vesion. Maybe I can stil sus this out on my own... well, with a lot of help from my friends! Nellie Wilson | ||
| Don Evans (Doninwa)
Registered Member Username: Doninwa Post Number: 156 Registered: 1-2007 Posted From: 208.81.157.90 Rating: N/A |
The actual wiring has to be a bit more than the simplified diagram in the MCI bulletin. Must be a dimmer switch in there too. DPDT or some relays controlled by the dimmer switch? I'm guessing relays. Is there a service bulletin that details a retrofit to a earlier bus so we can see how MCI engineered it? Don 4107 | ||
| Gus Causbie (Gusc)
Registered Member Username: Gusc Post Number: 779 Registered: 11-2005 Posted From: 208.54.200.168 Rating: N/A |
George, My 24v Army truck is tapped at the pos terminal of the battery that is grounded. The pos of the other goes directly to the starter. I don't see how a tap can be anywhere else on series batteries?? I'm no expert either, just going by experience. I've never had any light or battery problems. It is possible one battery failed before the other but I have so many vehicles I couldn't possibly remember!! There are no relays anywhere and I think both hi and lo beams go through the hi/lo switch but it is too cold out to veryfy this. This truck was a vfd tanker and I'm sure the conversion was made by a fireman who was a shade tree mechanic just like me. The bottom line is it works and it is a great truck. | ||
| Ian Giffin (Admin)
Board Administrator Username: Admin Post Number: 1132 Registered: 7-1997 Posted From: 24.239.13.27  Rating: |
... as requested by George...  Ian www.busnut.com | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 544 Registered: 10-2006 Posted From: 66.82.162.13 Rating: N/A |
I would swop the batterys back and forth between the working one and the rider fairly often to equalize the different charge each will receive. The usual hassle with an "equalization " setup. FF | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 622 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
Morning Nellie, To answer your question in the other post, I am a licensed electrical and air conditioning contractor. I have an associate degree in electronics, and have done locomotive and passenger car electrical repair for the railroad I have worked for for MANY years. On to bigger and better things, thanks to Ian, the schematic is up. Fred just hasn't read it with understanding yet, so don't worry about swapping batteries, as you just don't have to. The relays are 24VDC single-pole, and I would buy the same self-resetting circuit breakers the factory uses. Some more acronym and jargon explanations: Swop=swap SOC=State Of Charge It was not deliberate, but there is a small mistake in the drawing, of no consequence, lets see who finds it? Good luck, George | ||
| Don Evans (Doninwa)
Registered Member Username: Doninwa Post Number: 157 Registered: 1-2007 Posted From: 208.81.157.90 Rating: N/A |
Diagram shows how to do it and can easily be adapted to fit any 24V system. Can't read all the labels, but since you asked: Dimmer switch does not have a 'center off' position. There is not a breaker on the 'balance' or center tap lead. Why two high beam indicator lamps? Only shows two head lights. As a side question, did MCI equip buses with equalizers? If so when did they start. How about Prevost? Are current MCI and Prevost 12 or 24V? Don 4107 | ||
| Wec4104 (Wec4104)
Registered Member Username: Wec4104 Post Number: 6 Registered: 7-2008 Posted From: 68.46.66.57 Rating: N/A |
The small mistake involves the line drawn to connect the left relay to the left headlights. Where the line crosses the two outputs from the dimmer, the line should have the little semi-circles to "hop" over the dimmer lines. I don't think anyone will misinterpret these locations as physical connections, however. | ||
| don goldsmith (Bottomacher)
Registered Member Username: Bottomacher Post Number: 208 Registered: 12-2000 Posted From: 72.15.86.59 Rating: N/A |
Can you explain the need for the two diodes that MCI installs in the headlight circuit? | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 623 Registered: 8-2006 Posted From: 207.231.75.253 Rating: N/A |
WEC wins the Eagle Eye Award! (Actually I blew it twice, there's no splice dot on the equalizer wire connection to the cable between the batteries.) Don E, Sorry for the poor quality of the drawing. THANKS for your first sentence! The four circles are the four headlights, I never thought about the high beam indicator light! I would assume it is connected to the high beam terminal of the dimmer switch, and the socket is grounded? If it is, then a 24V indicator bulb will work. A 12V bulb can be used by either connecting the socket ground to the equalizer wire, or the indicator hot wire to the left side high beam circuit. Deliberately no circuit breaker in the equalizer wire, in spite of a personal preference for short protection, due to both lights going out when one fails if the equalizer circuit is open. Don G, The diodes are in parallel with the relay coils, and connected so they don't conduct current when the circuit is energized. Their purpose is to get rid of the spike that occurs when the power is turned off and the field in the coil collapses, I think. BY ACCIDENT, they aren't needed in "my" schematic, as the relay coils are in parallel with the right headlight filaments and the grounded battery, and the spike will go away through them. Whew, and thanks to BW for getting me to do it! George | ||
| Jason Stahl (Flim63)
Registered Member Username: Flim63 Post Number: 1 Registered: 12-2008 Posted From: 69.110.192.196 Rating: N/A |
Can the two relays be replaced with one spdt (single pole double throw) relay with the n.o. contact feeding low beams and the n.c. contact feeding high? I WAS going to ask about placing the coil ground on the balance wire rather than chassis ground and using 12v relays, but that would have an unbalanced draw on the batteries, albeit a couple hundred milliamps. Would this be significant drain? Jason |
