wiring problems

[Mark31]

Fellows, this is not specifically a Dodge question, but I guess some of it applies to Dodges that don't have the factory tow wiring. I do know that there are some real smarties that hang around here. (Smart enough to buy a Cummins!!!) I am hoping one of you electric gurus can/will give me some help: I have an 88 GMC S-15 (my daily beater) that for years the dash around the headlight switch and especially the heat a/c control gets too hot. Today it got my attention. If I run the fan on the 3rd or 4th speed with the a/c, I have smelled hot wiring. I changed the scorched-smelling a/c control several years ago. All the grounds I can find have been cleaned. I carried mail in this truck from 88 to 97 (when I got a right-hand-drive Cherokee). It has 240k on it and I guess 9500 hours. Summers are long, hot, and humid here in northeast SC and all the years of heat I know have taken its toll on the wiring. 1. Maybe a couple of years ago, I saw an extremely thorough and neat article on wiring trailer lights so the load would not have to go through the headlight switch. Even though my trailer has LEDs, should I do this? Anyone remember this link? 2. Should I add a headlight relay kit (meant mainly for high power lights)? 3. Should I leave everything electric off untill I can "take out a second mortgage" and get a new wiring harness? Or just park it until then? Just replaced the alternator (bad bearing) What is causing the heat? Any help would be greatly appreciated!! Mark

 

[jelag]

When mechanical connections in switches carry too much current they tend to heat up... also as these contacts get old from making and breaking these connections they get pits on them... . all this leads to a bad connection...

When there is a bad connection in an electrical circuit, the electricity has to overcome that bad connection. A bad connection is the same as a heating element, in other words, that connection heats up... so what your feeling in the heater controls and head light switch is the current through a bad connection...

There are two reasons for this... . 1 - the switch was designed to do just a certain amount of work... never over engineered as that costs more money... 2 - with age the connections go bad in the switch and they heat... . and 1 and 2 together and the result is not good... .

The answer is to either replace the switches or at least take the load off of them with relays...

Relays will connect directly to the battery through a fuse and supply power to the head lights when the head light switch triggers the circuit... thus the load (large amperage draw) goes from the battery, through a fuse, to the head lights and the trigger is supplied by the head light switch...

The draw of a relay is something like 1/10 of an amp compared to the average draw of a 60 watt head lamp of (65/12=5. 4) 5. 4 amps per lamp x's 2 lamps, or about 10 amps. .

We have a large Class 8 truck and I opened a panel one day to find 30 relays... every circuit in that truck is supplied by a power buss and relay... . heater fan blower, head lamps, tail lamps, heated mirrors, clearance lights, power to the CB, refrigerator etc... etc. .

The most common relays are rated at 30 amps each, and are only $3-5 from wholesalers in lots of 10... I think the last ones I bought for our changes in our 08 5500 were 6. 76 each with the plug and harness...

Hope this helps answer your question...

 

[GAmes]

It is an easy job to wire the trailer running lights to a toggle switch bypassing the stock wiring. I've done that on my truck even though it has a factory tow package. It really came in handy for me earlier this year when the splice that sends power to all the lights mounted on the bed failed. Since I was towing a trailer I had tail lights and running lights on it and was able to complete my trip.

 

[WilsonF]

The relays help all lighting systems not just the "high powered systems" They do two things, 1, reduce the load on the switch,always a good thing for our trucks. 2, put more voltage to the head lights, allows them to burn brighter. Just a couple of good information sites: Catalog

Daniel Stern Lighting Consultancy and Supply

Floyd