KW Electrical Problem

This wire is getting really hot when driving, especially hot when applying the brakes. Hot enough that it starts to smoke and I can see it glow around the metal connection. The black plastic is melting too. I'm going to get a new electrical block but I'm not sure if the piece is shorting out or there is a problem down the line. I would think if there was a short it would pop a fuse. Please advise. Thanks Mike

Mike, Isn't that one of the main feeds to the strip with the breakers for the lights and most of the other cab electrical functions? The breakers are in the circut after that buss bar. I would check for a rubbing main feed wire grounding out before you burn that nice rig down. The power likely comes from the input stud on the starter where the battery cables attach. Breakers trip, the old style reset when they cool off.

Mike-

The problem may just be a poor connection between the wire and its terminal. It definitely (after having been hot) has a poor connection now. The connector, if it's a high amperage circuit, should be (if it doesn't have to be insulated) a "high temp ring connector". These would be available at Coast Appliance on 18th St (get the appropriate size). Also I would recommend using a crimping tool with a rounded "poker" to crimp rather than just a squeezing type. Cut the wire back far enough to get virgin (not discolored) copper and crimp as tight as you can. Clean the other terminals on the same stud (they've been hot too).

Daron

is the wire getting hot back further from the teminal ie like 12 18 inchs because if its not it will just be a loose connection and it wont take much amps to make the wire really hot and burn off chop wire off near the lug discoloured wires dosnt mean anythings wrong with the wire just a bit of vertigrease [my spelling isnt real flash] on the wire dont get it in your eyes stings like all get out

Paul

Kenworth has been known to have poor connections. They get a little crusty and fry the harness. I have seen it on a couple trucks personally. You dont need to replace the buss bar. Cut that bad end off and replace with a well crimped end. You can then hook it to any other terminal on the buss bar.

Looks to me that the red wire is carrying the load of the whole bar as it is the only one attached to metal. Bad connection -yes -but it might be carrying more current than intended. Just something else to check.

BullDozerBob

I cut the wire back 1" and it looked just fine. So I crimped on a new "regular" #10 stud x 10 GA ring with a popper crimper as Daron suggested. Went out to my parts truck for a new/used fresh nut and the same thing happened to it "hot melted plastic". Now the ring is on a center stud. If it acts up this weekend when Pete and I go get Dans water buffalo and D4 I'll definitely put a high output connector on it.

Thank you for the replies.

[quote="Mike Mc"]I cut the wire back 1" and it looked just fine. So I crimped on a new "regular" #10 stud x 10 GA ring with a popper crimper as Daron suggested. Went out to my parts truck for a new/used fresh nut and the same thing happened to it "hot melted plastic". Now the ring is on a center stud. If it acts up this weekend when Pete and I go get Dans water buffalo and D4 I'll definitely put a high output connector on it.

Thank you for the replies.[/quote]

Mikee, just for grins, I would parallel that wire, and solder the stake-ons, along with crimping.

Please explaine in more detail?

One thing I would make sure is do all the brake lights come on. If not, there is a possible short to that whichever light fails. Also it would be good to know if there is a high residual amperage before the brakes are applied and the brake application just takes the load over hump.

I would put an temporary amp meter in the circuit to find out more info.

Hi Mike,

all good advice here, I would definitely solder the crimp on connector you use, the connector may not have enough current carrying capacity to handle the full load of the bus bar, never seen a night shot of your old KW, but I assume you have it lit up pretty good, you can try and figure out if you have additional load by removing one circuit at a time, using a DC ampmeter, or replace any incandesant bulbs or lights with LED's. it is also possible that one of the branch circuits has rubbed through and is shorting to ground causing increased load like someone previously mentioned.

Have you checked all the grounds between your chassis and cab? sometimes you can get some stray current if one of the bonding cables is corroded.

when you installed the new crimp-on end, did you wire brush the terminal really good to remove any oxidation, corrosion or melted plastic? this can cause a poor connection which creates heat.

looks like you have aluminum bus bars in the one pic, John deere used to use aluminum bus bars in their 30, 40 and 50 series waterloo built tractors. there was a change up to copper bus bars as they do not expand and contract as much as aluminum, the expansion and contraction due to heat load from the current would cause the nuts to come loose and faulty connections were the result.

what soapy means by parallel the wire is to find another piece of wire the same guage, and run two wires from the power source (ie the battery cable or relay post that the big red wire originates from, and run it to the other end of the bus bar. two wires would in parallel to provide the power. this would cut the current that has to be carried in each wire in half as to what the existing wire has to carry for a total current load.

the batteries on your truck may be connected in parallel if you are using 12 volt batteries. if you are using six volt batteries, then you would have to be using 4 batteries in total, you would have two pairs of six volt batteries in series (the positive of the first battery connects to the negative of the second battery) which would basically create a 12 volt battery. the other pair of six volt batteries would also be connected in series. then the positive from the second battery of each pair would be connected to the starter, while the negative of the first battery in each pair would be connected to the frame. which would create two 12 volt sources in parallel. either way you have enough cranking amps to turn that big old engine over.

Highway trucks used to use a series parallel switch, but the went the way of the dodo, as they weren't the best system and caused a lot of confusion and headache as you had the balance the load on the system, the series parallel switch would put the 12 volt batteries in series and crank the engine on 24 volts, when the starter wasn't engaged the switch would switch to parallel and the truck charging system and all lights accessories would run at 12 volts.

something has changed in your truck, you have been running it for a long time with no apparent electrical issues, now this has come up, since it is the power feed wire that is overheating it is obviously seeing more current draw then it previously did. have you added any additional electrical loads to the truck? how about your trailer? have you inspected the harness on the trailer? sometimes the connectors get corrosion inside them that causes a short to ground through the corrosion. or is the wire harness on the trailer rubbed through to the frame underneath somewhere that is causing a current draw or short to ground?

does the truck show the same symptoms without the trailer attached?? It looks as though you may be treating the symptom, but are not inding the root cause of the problem. a very simple way of finding the root cause of problem is to ask "why?" five times. this is how it would work:

Q1:Why is the wire getting hot and letting smoke out?

A: because it is carrying more current than it is designed to carry

Q2: why is the wire carrying more current than it is designed to carry?

A1: because I have lit my truck up like a Christmas tree

A2: Because I am towing my trailer and it has more electrical load

A3: Because the brakes are applied

Q3: why is the excessive current on the wire when I apply the brakes?

A1: more lights are in use when brakes are applied
A2: Brakes lights are a considerably higher wattage than regular tail & marker Lights
A3: the brake circuit is shorting to ground somewhere on the chassis or trailer.


in this scenario a person didn't need to go the end of the five why's, but they found a tangible answer, note there are multiple answers to the second question, start with the most credible, easiest to diagnose and move on from there.

If you follow the above rationale, I would first disconnect the trailer and see if the problem persists, this way you know that it is either in the truck or the trailer. if it is still present in the truck than inspect the chassis wiring inside the frame for any rubbed spots or swollen spots in the harness. swollen harnesses if they are rubber encased or taped up with electrical tape can indicate corrosion.
also inspect your trailer connection cable as it may have been inadvertently pinched between the deck and frame or something when you are switching back and forth between your trailer and beavertail deck.

if you determine the problem is in the trailer, inspect the harness and use some jumper leads and a battery to test individual curcuits. you can also use an ohmmeter and test for continuity to ground, but this is not the most accurate way as almost all trailer circuits have some continuity to ground through the various bulbs.

the battery and test lead method may work as you will see a bigger spark on the circuit that is causing the most draw which will help you to narrow it down.


Hope this helps.