Ignition switch wiring
 

My new to me truck has some electrical fire issues the PO had. I believe it has to do with the ignition job he did.

Heres a pick of how im wired now. The wiring diagram has brown and purple together, which mine does not. This isnt the factory switch so im alittle confused on the locations.

I have (going clockwise) Red on "bat"(yellow collar) , tan and brown on "Acc", pink on "Ign", and (in middle) purple on "St".

The stray frayed wire comming from "Acc" was the "brake warn light", it got incenerated all the way to the fuse box. I did away with the wire completly and said forget the brake light, i'd rather my truck not burn down than risk recreating a fire. So i guess i can ditch the other tan wire on "Acc", its for the brake light too.

Questions....

On the factory diagram, which termanals are which?

Im good ditching my brake light warning setup right? No other systems connected?

What is "St" on my ignition stand for?

I know im missing the resistance wire for the alternator, it wasnt included by the PO. According to the diagram it should go to the purple wire also shouldnt it?



http://i120.photobucket.com/albums/o...e/HPIM0834.jpg

http://i120.photobucket.com/albums/o...59575fe1_o.jpg

Re: Ignition switch wiring
 

here is a bigger picture of the factory switch. Your switch is missing some wires and depending on which wires you have on it, it may short to ground. The purple wire is the starter solenoid wire and goes on the ST terminal. No other wire goes there.

The red wire is the power wire from the battery.
The brown wire is the accessory wire
The brown/white is the alternator wire to the external regulator for a gauge dash,not an idiot light dash. On those it goes to the alternator light. It goes with the brown wire not the purple.
The pink wire goes to the firewall block for the ignition coil.
The tan wire is for the brake warning and then to the dash cluster to the warning light
The green wire is from the temperature sender and goes to the dash cluster
The dashed purple wire is the same wire as the other purple and it goes to the neutral start switch for automatic transmission trucks.

There's no reason to do away with the brake warning wires because they are just grounding wires for the light in the dash cluster. Don't connect them to any hot wires on the key switch. The key switch grounds the tan and green wires when it is turned on as a check for the lights in the dash cluster . I will check the diagrams again just to be sure

Re: Ignition switch wiring
 

Here's a shot of the ignition sw borrowed from American Autowire.

Re: Ignition switch wiring
 

Ok, so im wired strait?

Pink to "ign"

Purple to "St"

Red to "bat"

The heavy brown wire, the alt field wire, and the warning lamp wires all go to the same terminal..."Acc"?

And this Acc terminal is just a ground to complete the circuit?

Any guesses y a ground would burn up end to end? I thought it would need voltage to burn up.

Re: Ignition switch wiring
 

Re: Ignition switch wiring
 

I also have a ignition wiring issue on a truck I just bought.

To keep things consolidated, I posted here rather than starting a new thread.

I think the ignition switch has something wrong for the previous owner to have it wired this way.
If I take something metal and arc the center post with the post to the right (purple wire), the engine will crank and start.

Pictures help me:
http://i55.tinypic.com/rv96pu.jpg

Here is the wiring at the ignition switch:
http://i54.tinypic.com/ezlx7a.jpg

It appears I need a Purple wire to the center post, and a couple browns to the ACC Post.
But I'm thinking the previous owner left them unconnected because of some electrical issue.

Where should I order a new ignition switch from?
The one the truck has now is just hanging there, so I'll also need the OEM nut that connects the ignition switch to the dash panel.

Re: Ignition switch wiring
 

All my research shows this as the ignition switch, is this what it should look like?
http://i55.tinypic.com/2q068ed.jpg

Re: Ignition switch wiring
 

if the relay is on the starter you shouldn't have the second (burntish)wire there.but where does it go?

Re: Ignition switch wiring
 

I'm really thinking myself and the OP have the wrong switch.

More evidence that this is the correct one:
http://i55.tinypic.com/14ngrwh.jpg

Re: Ignition switch wiring
 

any part # on the old one?is the key a gm key?

Re: Ignition switch wiring
 

I'll try and check tomorrow morning.

Re: Ignition switch wiring
 

This post jives with the 5 prongs on the correct switch:

Re: Ignition switch wiring
 

This is for the 66:

http://67-72chevytrucks.com/vboard/a...1&d=1276020030

Re: Ignition switch wiring
 

I'll check that also.

Thanks

Re: Ignition switch wiring
 

Ok thanks VetteVet and all u others. My generic switch has only 4 posts while the factory has 5. I dont have any ground terminals on my switch.

But that explains the fire, proportioning valve to hot on "acc". It put voltage to my ground.

Im just gonna leave the ground wires (brake warn and temp light) outta the picture until i get a factory switch. I just need to hook up my alt field wire to "acc" and get that other ground wire off. Thanks again guys.

Re: Ignition switch wiring
 

IMO the ground function of the ignition switch serves an important role, in that it lets you know the brake and temp warning lights are working without that bulb check function the bulbs could be burned out and you wont know it even if your brakes go out you wont have any warning. You could still take advantage of the bulb check wiring with that generic after market switch you'll just have to use a relay to do so. Use the purple wire to trigger the relay (terminal # 86) ground out terminals 85 & 30 and connect the tan and green wires to terminal 87. That way whenever you crank the engine it also energizes the relay and grounds out terminal 87 (bulb check).

Re: Ignition switch wiring
 

I'm just going to order the correct one.

http://www.lmctruck.com/icatalog/cbe/full.aspx?Page=88

Re: Ignition switch wiring
 

Here is a related article for the dash lights:
http://rmcavoy.freeshell.org/Truck_gauges.html

Re: Ignition switch wiring
 

While I think you are correct to use the factory switch, let me point out that you will need the harness plug and terminals and you need to be sure you'll have enough wire to reach the key switch after you convert.

Re: Ignition switch wiring
 

good read

Re: Ignition switch wiring
 

I see no part #.
It's not a gm key either.

I decided to order a whole new keyed ignition from LMC.
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Re: Ignition switch wiring
 

My new ignition switch arrived this last week, and I wired it yesterday. It has the five prongs like the pic above.

I did this:

BAT-Red
ACC-Brown/White
IGN-Pink
GRD -Dark Green
SOL-Purple

All is good now.
Everything works as should.
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Re: Ignition switch wiring
 

and this is what happened to me, and now im backtracking trying to figure out why, VV your the top dog, you know it all you have answered many of my questions before and thank you! :metal::metal::metal:

Re: Ignition switch wiring
 

Are all these wires the same gauge of wire?

Re: Ignition switch wiring
 

This is so sick, I actually had the exact same issue, same replacement switch with incorrect wires, and got hold of the correct switch, identical to all the pics from the OP, this is amazing, awesome help guys thanks