electrical problem far from home

[Stan Simpson]

We are about 1000 miles from home. Today, we experienced an electrical problem with our Beaver, and have some questions.

About half way from Grand Junction to Denver, our tail lights, marker lights, and dash lights went out. The tail lights on the toad went out as well. Headlights, brake lights, including the third brake light, and flashers all worked, on the coach and the toad. All turn signals worked.

We stopped at a rest area, and I got out the manual. I found a section on the chassis, and showed an electrical schematic just like the one pasted on the inside of the electrical bay. I figured we must have a fuse out. I found the corresponding names for the failed parts, however, both the manual and the electrical bay show only "relays" labeled "marker lights", "tail lights", etc. Are there fuses some where else. I looked high and low and could not find any.

When we stopped for fuel on the way to Cheyenne, the lights that were out, suddenly worked! However, just after we were underway, they went out again. We limped in to Cheyenne using the flashers on the coach and the toad in lieu of no tail lights. I'm now thinking there is a short somewhere? I have no idea where to look.

Does anyone have any ideas how to look for the possible short? Does anyone know where the traditional type fuses are, or if there are any?

As always, any help would be appreciated.

Stan

As additional information, I should tell you that before leaving Grand Junction this morning, we had our 50 amp shore power cord replaced. After the repair, when we hooked up the toad, we tested, as we always do, all lights on the coach and the toad, and they all worked fine. The reason for the shore power replacement was because someone forgot to replace the cover that goes over the hole the cord goes through, which allows the bay door to be closed. The 50 amp cord flopped around behind the coach for several miles until a motorist brought it to our attention. An expensive lesson to be sure. Is there a chance that this could be the cause of the problem?

[Mark Bryant]

Stan


Sounds more like a loose connection somewhere or a loose ground. I would check the black connectors in the electrica bay to the left of the relays.
Your 50 amp power cord is independent of the 12v system.

[Keith Moffett Co-Admin]

Stan
We just had the same problem or very close.  No lights on tow car, no lights on plug for tow lights, most or all of the marker lights went out and more.  We paid a shop to trace the wires starting at the tow plug and going forward.  Of course the problem was all the way up front.

In our electrical bay the wires come off the circut breakers and terminals and are bundled into a loom with ties.  At the floor of the bay are some black matrix plugs joining parts of the loom with some of the circuts.  The rest of the loom travels out of the bay from behind the backing board to which the terminals are mounted.  The loom uses more matrix plugs just after exiting the bay and that seems to be a problem area.  These plugs (on ours) are round male / female connectors with 15 - 20 very small pins each.  One of the pins had been overheated at the original build and was not held in the plastic mold securely.  It finaly decided to come loose.

Trace the wire marked 'Parking Lights' and see if there is power to both sides of the connector.

Good luck, I sure feel for ya!

Keith

[Edward Buker]

Stan,

This may help narrow the search a little. Because all of the lights that one would expect to be on one circuit went out together it must be a major supply point that is failing before branching to other locations. That would mean the main power feed area to this circuit like a bad relay or a wire connection near there. I say that because the dash lights went out also. The dash lights would have their own ground and plus feed up by the dash so I do not think it is a ground wire issue that is affecting all of this. I have not seen a fuse go and then fix itself but I have seen a fuse holder with poor connections become intermittent.
I believe that you are looking for an open and not a short given this system must be fused or have a circuit breaker somewhere that would be tripped unless this circuit has a thermal type breaker that resets itself.

I would turn on and off the switch for the lights and using a meter find the relay or relays that are powering up with the switch. Check the output of the relay to see if 12v is provided when the coil circuit is activated. If not you have a bad relay and could temporarily make a jumper if a relay was not handy. You can wiggle the plugs and wires a bit in the electrical bay near the relays and see if the lights flicker.

The simplest way to look at this problem is, the dash lights are out, why is that? Trace why the 12V is not being supplied between the dash lights and the electrical bay 6ft away and when you solve that problem the rest of the lights will follow. A Smartwheel system could be involved but I do not think it is the issue given the dash lights I believe are independent of that system. Hope this helps narrow things down a bit and head you in the right direction.

Later Ed

[Steve Huber]

Stan,
Tighten all the connections in the electrical bay, both ground and hot. Because of the multiple terminals stacked on the threaded posts, they can become faulty connections very easily if the nut loosens just a tad, which can result in an intermittent connection. I tighten mine annually.
Good Luck,
Steve

[Stan Simpson]

Thank you all for the great suggestions. It has stopped raining finally, so I will be testing this afternoon, and will report the results.

Stan

[Larry and Heidi Lee]

Stan, I didnt see you mention if you isolated the Toad from the tow vehicle? I've had my tow vehicle cause a short once.

[Stan Simpson]

Well, I jiggled the relay named K1 on the schematic and lo and behold the tail lights and marker lights came on. However, the dash lights are still out. Even when the coach is running.

In the middle of the electric bay, there are 5 rows of multiple wiring connections. The third row from the left has a connection 5 up from the bottom that is labeled "instrument panel" on the schematic. I tried the suggestion of tightening the connection, but still no dash lights. The speedometer, gauges, and all of the toggle switches are still not lit.

Perhaps there are two problems? 1. The marker and tail lights are intermittent because something is loose on relay K-1? 2. The dash lights are a short?

What do you think. Thank so much for the help.

Stan

[Edward Buker]

Stan,

It seems unlikely that you have two lighting issues in the same circuit that have independant causes at the same time. If you noticed that the intermittent nature of the lighting fail in the past caused the dash lights to go on and off with the marker and tail lights, all at the same time then they have the same cause. If you have a schematic, and can either trace the dash light wiring and relay circuit yourself, or get some help to trace the dash light circuit from the dash to the electrical bay, you should be able to find the source of the problem.

Regarding relay K1, it was not clear if that relay was the source of your problem. If you suspect that relay, buy one and change it. If that solves the marker and tail light issue, then you are down to one problem set, the dash lights.

Later Ed

[Steve Huber]

Stan,
The K1 relay has spade connectors.  From what you've said, I strongly suspect the problem is with one of the connectors not making good contact.  Wiggling the relay could cause it to recover (temporarily).  Suggest you unplug and then re-plug each of the wires on the bottom of the relay.  If this doesn't fix it, then it is probably the relay itself.
Not sure what's going on re the dash, but suspect a bad connection.
Steve

[Joel Ashley]

As Keith mentioned, the big plugs (loom connectors) in the electrical bay have pins and holes that can corrode, causing high resistance.  I don't think there are any fuses involved in your issue, but rather breakers instead, that should automatically reset.  An unresolved issue will cause the breaker to keep shutting off the circuit.  I had to cut a few plastic ties in order to get a grip on the connectors and pull them apart, but I did find one or two pins that showed tell-tale green bloom, but we're easily cleaned.  I then used Corrosion-X and dielectric grease on all connections and junction posts/nuts in the bay to help prevent more problems.  Even if your present issue isn't ultimately attributable to corrosion in the bay, it's still a good idea to corrosion proof in there.

Joel

[Stan Simpson]

We are home now, so I can spend some time with the problem. Its still intermittent. When I pull the lights on, everything comes on, tail lights, marker lights, dash lights, and the rows of switches on the front panel and the panel where the transmission selector is located.

After a few minutes everything goes off. A few minutes later, I turn it on and all work again. The in 3 or 4 minutes...off.

Going to really do some tracing to see what I find.

Stan

[Edward Buker]

Stan,

You should not overlook the possibility that it could be the light switch as part of this check out. You could have worn contacts and with some heat being generated they open up and when they cool they make contact again. Something mechanical like a switch or a relay has a tendency to be intermittent.

Later Ed

[Joel Ashley]

You do need to consider that the light switch itself could be bad, as Ed points out.  Our old coach had a bad switch that took our headlights out at night on I-5, the very first trip we took in a motor home in 1985.  If somewhere along the line there was a heavy draw that overheated the switch, enough damage could have been done that it no longer can tolerate much amperage for very long.  Some, like the one in our old rig, had a built-in breaker, and conceivably that could be what's haywire with yours, though you said the headlights weren't involved as I recall.  There could be more than one breaker in the switch I reckon.  The lights involved are all functions of the running light circuit, position 1 on the switch.


My instinct, given your symptoms though, would still lead me to an overheating breaker or relay in the bay.
Joel

[Gerald Farris]

Stan,
I think that the circuit or circuits that you are dealing with are protected by automatic resetting circuit breakers. If so you should be sure that the circuit is not just functioning normally and opening the breaker because of excess amperage draw. If the problem is excess amperage draw, you will need to eliminate the excessive draw or divide the circuit, if the breaker is not defective and tripping to soon.

Gerald