First Gen Wiring

[RSchwarzli]

I have heard many times that the wiring circuits in our trucks are barelly adaquete. I have heard this refering to the running lights circuit, as well as others. Is this true? How many other things can be wired into these circuits? Is it the wires that are weak?



I ask as I have installed a second gen alternator onto the motor. Will this cause an issue with the increased amperage? Will I melt wires?



Thanks!



Robert

 

[sdstriper]

I would be especially concerned if there is a trailer brake controller wired in using the factory harness instead of seperate wiring from the cab to the rear of the truck. The headlite switch tends to be a problem circuit, wiring and connectors need to be checked, cracked insulation etc. A couple relays and larger diameter wiring goes a long ways on the headlites, relay the trailer running lights if you pull.



Is there a bunch of accessories added? Are they wired stand alone with fuses or tapped in?

 

[dpuckett]

sdstriper-



WHat factory harness are you talking about for the brake contoller? I didnt think 1stgens had a factory socket for a brake controller.



OR are you referring to the blue wire that the instructions with most controllers say to run from the controller output to the back to the brake socket in the wiring plug? How does one run it in the factory wiring? I tapped the brake light circuit to energize the controller.



Daniel

 

[sdstriper]

They don't have a factory brake controller harness, but people do tap into the wiring instead of run seperate wires from the controller to the back of the truck. Bad idea. There is a connector kit you can buy for the 87' up trucks that plugs in at the rear, unplug the taillight connectors and plug the kit in, gives a 4 flat which you can then plug into whatever trailer connector you chose. I like the RV seven pole with the 4 flat built in too.

 

[RTRAM]

Does anyone know about replacing the fusible links with fused circuits? I had a short and the fusible link blew and it was a mess trying to replace it. I would like to replace all of the fusible links, but don't know what size wiring to use

 

[Philip]

I would like to replace all of the fusible links, but don't know what size wiring to use

Do you mean take the fuse links out completely?



Are you planing on providing circuit protect some other way?

 

[cojhl2]

Does anyone know about replacing the fusible links with fused circuits? I had a short and the fusible link blew and it was a mess trying to replace it. I would like to replace all of the fusible links, but don't know what size wiring to use

I wouold never replace the fusible links as they provide some delay before giving up on a circuit short.



NAPA has all the fusible link wire avail. All you have to know is what size wire you are trying to protect.

 

[cojhl2]

I ask as I have installed a second gen alternator onto the motor. Will this cause an issue with the increased amperage? Will I melt wires?

Robert

The larger Alternator would have no efect on amperage in the way you asked it. The amperage is determined by the demand not the source potential to produce it.



If the new alternator kicks up the voltage, then it is possible that amperage on the demand circuits could increase, however this is unlikely because the battery will act as a voltage limiter anyway.

 

[KOG]

I've replaced some fuseable links with slow blow fuses on other vehicles and have no trouble with them. I've also replaced fuseable links with new ones and it's a pain.



When you use fuses just use a fuse holder rated for 30 amps and you've got it covered. But do NOT over fuse the circuit. 12 ga wire, 20 amp fuse. 14 ga wire, 15 amp fuse. 16 ga wire, 10 amp. That's a smaller fuse than car makers normally use, they tend to overfuse by about one wire size relative to house wiring.

 

[blacksheepdiesel]

KOG,



Thanks for the wire size/fuse size guide. I am going to purchase a used Power Distribution Center from a 2nd Gen and install in my 1989 W250. The wiring near and including the fusible links is junk!



As asked above, has anyone done this yet and can give pointers?



Godspeed,

Trent

 

[RTRAM]

Thanks for the info on the wire size. I bought a fuse block from Painless from Geno's and that will give me hot and cold circuits.