Chassis Short or Bad Ground?

ClydesdaleKevin · November 05, 2012, 08:05 AM

Hey guys, me again. This time with a chassis electrical question. These are the symptoms, so tell me if you think its a bad or loose ground causing these problems, or an electrical short, so I'll know what to look for when I'm tackling this this week:

Since we bought the RV, when I turn the signal lights on the volt meter on the dash bobs in time with the signals...and its gotten worse, with more bobbing of the gauge needle.

When I turn on the headlights, the volt meter drops and says I'm at less than 12 volts, even though my Fluke is reading over 12 volts at the battery, even at idle, and 14 or so when Patti holds the gas pedal down to keep the engine at a higher RPM.

Another symptom, maybe related, maybe unrelated. If I turn on the high beams, they run okay for a minute or two, then start to flash! Could that be a bad ground, a short, or just a tired and weak old relay? I thought it was the pigtail at the high beam, but I replaced that already and its still doing it.

And the last symptom, which it just started doing: We have fans in the cockpit that blow air on the driver and passenger on hot days, mounted at the upper corners above the windshield. They've never been problematic, but now when we turn them on, the volt meter on the dash dips WAY down and the lights dim.

By the way, the ignition switch is brand new, as is the headlight switch. The signal switch/high beam/cruise control switch is original.

Thanks ahead of time guys! I really have to get this sorted out soon, and have no idea where to start!

Kev

dgapilot · November 05, 2012, 03:28 PM

Bad ground on any machine as old as these MHs are is a likely culprit. Do you have a wiring diagram for your rig? If so look and see if each of these systems have a common ground. The first one I would go after is the engine to chasis ground, and work back from there. If the battery volts don't take a dump when you turn on one of these systems, I would think you don't have a short. You might want to get a clamp on amp meter so you can verify what the amp draw is. Something else you may want to look at is the connections to your volt meter. You may have some corrosion built up on those connections giving you false indication. The high beams starting out good and then going crazy can also be a sign of a connection that changes resistance as it gets hot, i.e. a loose connection or bad ground.

Again, since you are getting indications with multiple systems, look for the common connection.

David

gadgetman · November 06, 2012, 02:17 PM

Sounds like a voltage drop o n the supply side to me. Check the main power wire feeding the fuse block and its path to the battery, Headlights don't run off the ignition switch so its before that. For it to be a bad ground it would have to be the main chassis ground to have all those in common. May even be a old fuse link causing the low system voltage. IE volt drop.

If you have a volt meter, do a volt drop check, simply put the red lead on one side of a pos connection and the black lead on the other side of the connection being tested, Now you have to power the circuit "turn it on" and watch the meter. anything over .300 is a problem, yours would read much higher by the description tho, like 1.5 or more. You can test pos or neg connections this way. Just remember current have to be flowing IE circuit ON !

M & J · November 06, 2012, 02:18 PM

When I first got Betty home I had very similiar problems as you. hi and low beams would cause the right front turn signal to glow dimly, sometimes having the hi beams on would have one of the low beams come on or glow dimly. Sometimes the turn indicator in the cluster would come on when the headlights would come on.... I never noticed what the voltmeter was doing since I had a charger on the battery while testing to keep from draining the chassis battery.
It seemed like a massive rewiring was in order. However, I traced all front clip wiring and found nearly every ground at or in front of the dog house was either badly corroded or broken. I replaced every ground wire and cleaned/replaced every ground connector. What I found was because of the common grounds and connection through the headlight switch, the headlights would attempt to find a ground through the switch or bulb socket and finally through one of the turn signal (well, actually parking light) bulbs. Also, a high resistance ground will cause more current to be drawn which could be causing your volt meter to fluctuate.
And where are you guys camped right now? I missed that in your thread.

HandyDan · November 06, 2012, 05:49 PM

When I went to have my HR inspected the turn signals would not work properly. I discovered that the signal lights on the front were corroded enough that they had lost their ground. They are grounded to the chassis by the bolts holding them in. I used two pairs of alligator clips and clipped one end on the bolt and the other end to the chassis on each one. Problem solved. I'll bet yours is something similar.

DaveVA78Chieftain · November 09, 2012, 05:57 PM

QuoteAnother symptom, maybe related, maybe unrelated. If I turn on the high beams, they run okay for a minute or two, then start to flash! Could that be a bad ground, a short, or just a tired and weak old relay? I thought it was the pigtail at the high beam, but I replaced that already and its still doing it.

Headlight switch is designed with a "self resetting" circuit breaker built into it. When to much current flows through it it opens, cools down then automatically closes. So, you are pulling to much current through the switch resulting in flashing headlights. Not sure how Holiday Rambler "tapped" into the tail light circuit to power the overhead marker lights. Proper way is via a relay. Headlight switch feeds the relay coil and the relay feeds a seperate power source to the overhead marker lights.
While this is a simple circuit, without electrical wiring diagrams this is going to be difficult to trace down.

Dave

ClydesdaleKevin · November 14, 2012, 07:58 AM

Thanks for all your replies guys. I'm going to once again tackle this on Monday.

What I've found so far is a HUGE rats nest of wires under the rear bumper where POs wiring in 3 separate types of trailer plugs, so I'm going to clean all that up to the factory wiring. There are 2 obvious bad grounds back there as well which will get regrounded.

I went ahead and cleaned and tightened most of the ground connections in the front, but ran out of time yesterday to do them all. I'll do ALL of them on Monday. I also bought a new headlight relay and we'll see if that has anything to do with it...had to get an electronic flasher relay anyway for the LED signal light bulbs, so I picked up the one for the headlights while I was at it.

The headlight switch is brand new so I don't think its malfunctioning, since with the old one installed it was doing the same things, including the flashing high beams.

I suppose that if ALL of that doesn't work on Monday, I can run a new ground wire to the headlights and signal assemblies and ground them right to the chassis, and see if that fixes it.

How could too much current be going through the switch, by the way? Could bad grounds or loose connections cause that to happen? I'm somewhat at a loss here if cleaning up every connection and the rats nest of wires in the back doesn't fix the problem.

Thanks guys!

Kev

ClydesdaleKevin · November 14, 2012, 12:27 PM

I think I solved part of the problem with the electrical...the headlight flashing and such. I put the new headlight relay in, and even the low beams stopped working...cheap Advanced Auto chinese crap. So I put the old Bosch one back in and pushed it in really tight, tightened the ground wire running from it, and turned the lights back on with the engine running...no more flashing! I left them on for over a half hour. I think its fixed!

Then I put in the electronic flasher relay, and with the lights out the signals work, but with the headlights on they wouldn't. Hmmmmmm...All was well until I added the last 2 LED lights to the system. When I plug in the last two lights, the flashers work with the headlights out, but not with them on, and with those last two 1157 LED lights in place, only the rear LED flashers work...the side markers that blink when the signals are on and the side running light go out. So I put back in the 1157 incandescent bulbs, and everything was fine again...go figure! It could very well be that the bulbs are defective, because I tried them in the Jeep tail lights, and even with the fronts still being incandescent, the flashers wouldn't work in the Jeep either. However, the two just like them I bought from the same place on eBay work just fine in the Jeep tow lights. For now I'll just leave those two as incandescent lights, since its only two, the very last two, which really aren't going to draw a lot of amps when we're driving at night, since every other bulb is LED now.

At some point in the future I'll try a different brand of 1157 LEDs and see if that is the problem, but for now, with the exception of the little LED license plate bulb and one for a map light I missed in the RV (on order, just not here yet), the LED project is as done as its going to get for now.

On Monday I'll devote a few more hours to cleaning up more grounds and connections, and then I'll go ahead and rewire the ratsnest in the back. Just the grounds I cleaned up already seem to have made a difference...the headlights seem to be working properly again, and the needle on the volt meter gauge doesn't drop as much when the headlights are turned on, and the needle doesn't bob as much when the signals are on, but it still does a little. Hopefully once everything is rewired or regrounded all the symptoms will go away completely.

Otherwise it very well could be that the alternator or external voltage regulator are going, both made by Lestek, which is out of business now.

Kev

HandyDan · November 14, 2012, 01:18 PM

Don't you just love that "A Hah!" moment when you discover the problem? Glad things are going in the right direction. I got under my HR and looked for a way to get on top of the gas tank like you described. No such luck in my case. There is barely two inches between the floor and the top of the tank. Just enough room for the hoses, fittings, and wires to clear.

M & J · November 14, 2012, 03:47 PM

Go back and read what I suggested Kevin. In my case with a high resistance ground, the headlights were seeking ground through the parking light filament causing them do glow dimly or in some bizarre configuration. When you installed the LED bulbs, since they are diodes, they only pass current in one direction so you effectively broke the path to ground the old filament bulbs were providing theoretically. That is if I read and understood your new dilema.
Also, since the LEDs no longer or didnt initially work, there is a very slight possibility you smoked them instantly when you turned them on the first time IF the grounding through the parking lights is indeed your problem. Not sure, and don't panic. But I'd check carefully and make sure you have your other issues fully resolved before putting in fresh LEDs.

ClydesdaleKevin · November 14, 2012, 06:42 PM

Aw, that sucks Dan! It was a breeze getting to ours, but at least your electric pump is external.

I'm not so sure I'll bother putting in another set of LEDs. According to a lot I've read, depending on just how the chassis wiring is wired, sometime replacing the flasher relay with an electronic one works, like it did when we redid all the lights on our old rig the 77 Itasca, and sometimes you have to add load resistors to the wiring of two of the flasher bulbs, which I think is the case with the way our Holiday Rambler is wired. By leaving the front two bulbs as incandescent, they in effect are acting like the load resistors otherwise would. If I get more bulbs later on, I'll probably add a load resistor to both of those front lights, since they are way easier to get to the wiring for than the rears, which are built in with the wiring running through the walls.

I'm pretty sure I fixed the headlight flashing issue. Once I reinstalled the relay TIGHTLY...it was not pushed on all the way from the getgo...and cleaned up the cluster of ground wires right next to it...one of the wires from the relay goes to that cluster...the lights stopped flashing and ran just fine for over a half hour.

Monday I'll rewire the trailer plug and freshen everything up back there, and go ahead and clean and tighten every other ground connection and terminal connection I can find. If that doesn't do the trick, then I'm at a loss and would begin to suspect the alternator or the voltage regulator...or both...as the culprit, although I never have any problems with the battery not maintaining a charge. Of course, I'm also not sure how that's wired in...not sure if the converter charges the chassis battery as well as the coach batteries. I do know that when the engine is running it puts a charge to the coach batteries as well.

If it does end up being the voltage regulator, there is a company called PennTex that makes a compatible voltage regulator for my Lestek alternator...they also make direct replacement alternators, but they aren't cheap at around 400 bucks for the alternator. Heck, the voltage regulator isn't cheap, at around 120 bucks...ouch! But at least it would be a fix. If its the alternator, I think that at that point I'd just get a high output Chevy alternator with a built in voltage regulator and call it a day, since the mounts are the same and the pulleys would fit. Another alternative would be to send the alternator to PennTex when we are at our next big show in AZ and have them rebuild it...if its bad.

By the way, just how do I go about testing an alternator that has an external voltage regulator? What kind of volts should I see coming out of the alternator at a given RPM? What kind of volts should I see coming out of the voltage regulator?

Apparently the voltage regulator, and also the replacement from PennTex, has a separate circuit for the lights/lamps, so it makes sense that it COULD be the culprit.

And oh yeah...we are still in North Carolina until after Thanksgiving.

Thanks again guys!

Kev

ClydesdaleKevin · November 19, 2012, 08:17 PM

Found it! And right off the bat! Our dash has a couple of access covers on the top, and when I looked down inside, there are 2 clusters of common ground wires going to the mounting bolts on the speedometer, with two chassis ground wires coming from it. The speedo is held on by two knurled nuts...yeah, I expect the comments about Speedos and knurled nuts...lmfao!...and they were so loose I'm surprised the speedometer didn't fall out! The other chassis ground wire was just hanging there, not attached to anything. I added a heavy gauge wire to the hanging wire and grounded it to a clean connection.

Anyhow, I reassembled both sides with dielectric grease after cleaning the connectors, turned on the power to the chassis via the solenoid switch, started the engine, and tested the lights. NO MORE BOBBING!!! The gauge reads in the 13-14 volt range now, lights on or off, and the needle doesn't bob anymore when the signals are on...SWEET!

Its fixed! It wasn't the alternator or voltage regulator, it was a common ground problem effecting the whole system. I tried the fans for keeping us cool while driving, the ones mounted near the top of the dash, and no voltage drop or needle bob...it all had to do with a bad common ground that I was very lucky to find right away!

Thanks guys for all your input and pointing me in the right direction!

Kev