Electrical Work.

Discussion in 'GM Electrical Tech' started by Conlan Rose, Dec 21, 2012.

  1. Conlan Rose

    Conlan Rose Super Moderator

    Ok, today I spent many hours working on the truck fixing some wiring I messed up. Well it is all good now, but I need some diodes to protect the system from backward feeding power. Does any one know what I should use?

    I'm protecting my back up light from back feeding in to the reverse circuit and the reverse lights. The light is a 55w utility light, that is activated either by the reverse circuit via a relay or by a switch on the dash. I need to make sure that when the switch is activated it doesn't back feed to the reverse circuit.

    Other work I did today was install new bulbs in the climate controls 2012-12-21_19-00-19_489.jpg
  2. dpeter

    dpeter New Member

    If you go the relay route activated by the reverse/backup lights then no problems. If your back-up lights are activated by a switch on the transmision or the shift lever then you should have no problems with any back feeding issues when using a seperate switch. If activated by the body control module then maybe a blocking diode would be wise but not sure it would be neccessary. The only thing in my wiring diagram(99-06) is the automatic mirror adjust that would be activated by putting power to the back-up lamps.
  3. Jamm3r

    Jamm3r New Member

    Conlan

    The relay should do the job for you if you have it wired correctly, no diode required.

    Jammer
  4. Conlan Rose

    Conlan Rose Super Moderator

    So you are saying I should not have a problem because the relay is protecting the reverse circuit.
  5. Jamm3r

    Jamm3r New Member

    Yep. Unless you wired the switch to the relay coil, instead of in parallel with the contacts. In that case you need two relays. It's no big deal -- if you have a problem you'll see the reverse lights come on with the work lights when you use the switch, no damage done, just a nuisance problem.
  6. Conlan Rose

    Conlan Rose Super Moderator

    I was just looking for confirmation before I finished the wiring tomorrow. All I need to do is wire the switch to the light. Currently the light is only controlled my the reverse circuit.

    - - - Updated - - -

    Where does the orange wire for the trailer harness go to get power? I cant find it on any wiring diagrams, and there's about 20 orange wires that run to the dash and fuse box.
  7. SurrealOne

    SurrealOne Former Member

    I'd use a diode as you had originally intended. When I install my Dually D2's to have a relay that's triggered by either the reverse circuit or a toggle switch I'll be using a diode-approach similar to this (which has a Radio Shack part number for you, if you like): http://www.lunghd.com/Tech_Articles/Electrical/ReverseLights.htm.
  8. Conlan Rose

    Conlan Rose Super Moderator

    Ok sounds good.
    Here is a diagram of how it will be wired, the switch is rated for 20 amps which is far more then it ever will deal with.
    back up light wiring diagram.jpg
  9. Jamm3r

    Jamm3r New Member

    Typically to the "aux power 1" stud on the fuse block although it may just end in a ring terminal somewhere in the vicinity of the fuse block and not be hooked up to anything. I believe they left the factory that way and the dealer hooked them up, or not, at their discretion.

    - - - Updated - - -


    :: shrug ::

    That will work. The diode doesn't accomplish anything though, in this situation.
  10. Conlan Rose

    Conlan Rose Super Moderator

    I may be going with a different relay set up where it actually does something. I will run both the switch and the reverse circuit to the 86 terminal with both the switch and circuit protected by a diode. The switch will draw power from the aux fuse box under the hood.

    - - - Updated - - -

    It is not attached to the aux power one terminal and I have not found a ring terminal any where near the fuse box. I have found a female connector of some kind that just juts out of the wire loom. Could that be it? I can't tell the color of the wire.
  11. Conlan Rose

    Conlan Rose Super Moderator

    I will be buying the diodes very soon. Still trying to figure out how to hook up my aux trailer power :neutral:
  12. Conlan Rose

    Conlan Rose Super Moderator

    How do you trace where a wire goes. I need to know so I can find where my brake controller and aux power lead go to. Neither are on any wiring diagram I own for my truck. I really wanna get these set up. I may not be trailering that often, but I want to know I'm ready any time. Any one have a diagram even if it is a early 2000's.
  13. SurrealOne

    SurrealOne Former Member

    This link may save you some time: http://www.pirate4x4.com/tech/billavista/Chevy/tech/Prodigy/

    As for tracing a wire, what you do is turn the truck off, disconnect all power, connect an ohm meter to one end of the starting point of your investigation and to the other end of your investigation you connect a wire that leads back to your ohm meter. If the wire you are investigating provides a path back to where you've connected your ohm meter then the meter reading will drop from infinity to a low reading. If it doesn't then you've either investigated the wrong wire OR the wire you were investigating is bad (i.e. severed).

    Note: An ohm meter is preferred over a continuity tester, since continuity testers typically limit out at a maximum resistance and the combined run in the test circuit you've built (with the wire you used) could exceed the max resistance of the continuity tester.
  14. Conlan Rose

    Conlan Rose Super Moderator

    Lord is that gonna be a pain going from the front of the truck to the back. Luckily I have a multimeter that does ohms. I know how to install everything(which is a little different from your link) I just need the leads for installing. If I cant find the location of the leads I will just run my own wiring.

    - - - Updated - - -

    I found some info on another truck site saying the wire lead to just under the brake booster. I will have to investigate.
  15. SurrealOne

    SurrealOne Former Member

    Ya, the 90's vehicles are probably slightly different. The concepts should still be sound, though ... i.e. a fused positive 12v wire (which you may need to connect) and a blue wire that runs from your 7-spade connector to somewhere into the engine compartment. I believe trucks that came with the towing package should have both wires present...
  16. Conlan Rose

    Conlan Rose Super Moderator

    It does and they are attached to the trailer harness. That's the annoying part I need to find them on the front of the truck. The post I found on another site was about a 96 truck with the trailering package like mine. Some one earlier in this thread said his truck already had a terminal on the aux power lead on the truck and it was easy to find right by the fuse box:no:. I will try to find it if the temp goes up this weekend.
  17. SurrealOne

    SurrealOne Former Member

    My 12v wire was under the under-hook fuse box and needed to be connected to stud #2 in my truck. My blue wire was inside one one of the black wire looms leading into my under-hood fuse box.
  18. Conlan Rose

    Conlan Rose Super Moderator

    Mine is most likely near there too just yet to be found.

    Btw can the primary fuse box not getting enough power cause problems. I'm just wondering because my primary power lead is falling apart, the wire that is.
  19. SurrealOne

    SurrealOne Former Member

    Absolutely - fix that.
  20. Conlan Rose

    Conlan Rose Super Moderator

    The parts are already in the mail and will be in on the 2nd. KnuKonceptz Kolossus Flex Kable 4 Gauge Power Wire Red is what I ordered. It should work great :smile: Also got the lugs. It will be good practice for doing the 1/0 gauge cables.
    Last edited: Dec 28, 2012

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