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01-20-2021, 11:45 AM | #1 |
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Location: Jonesboro, AR
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Ignition switch wiring
I had a short that caused the connector to my ignition switch (68 gmc) to get hot. I bought a replacement but noticed that the wire locations don't match the old one. It appears that the colors on the new connector match pictures I've seen in threads on this site but the old one doesn't. Everything was working ok but I had a bare disconnected wire to short out that caused the connector to fry. Should I connect the wires on the new connector like the old one or get the wire colors to match correctly? Thanks for any advice.
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02-06-2021, 12:01 PM | #2 |
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Re: Ignition switch wiring
With all the wires cut, I measure 12.3V on the large red wire at the top in the photo. This wire is the feed from the battery so that should be ok. All others have no voltage except the large brown wire in the center measures 9.6V. Is that correct or does it mean I have a short somewhere? Help please.
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02-06-2021, 12:20 PM | #3 |
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Re: Ignition switch wiring
One more question; I have no wire to match up with the small red wire in the picture in the original post. What does that wire go to? Thanks again.
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02-06-2021, 01:47 PM | #4 |
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Re: Ignition switch wiring
I found a diagram that shows the following. Check out page 22 here: https://static.speedwaymotors.com/pdf/910510089.pdf
Red -- battery Purple -- starter Pink -- ignition Brown (at 3 o'clock on your picture) -- accessories. This will be hot in "ON" and "ACC" switch positions. The outer connector at 9 o'clock is labelled as "ground for warning lamp" The inner terminal at 8 o'clock seems to be another ground but it's not labelled. Do you measure 9 volts to that brown wire at 8 o'clock with or without the ignition switch plugged in? As for your main question, I'd put all the wires where they were before, since I assume things worked fine before the bare wire shorted to ground.
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Mike 1969 C10 LWB -- owned for 35 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, AAW wiring harness, 5-lug conversion, 1985 spindles and brakes. 1982 C10 SWB -- sold 1981 C10 Silverado LWB -- sold, but wish I still had it! 1969 C10 (not the current one) that I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming. Retired as a factory automation products salesman. Worked part-time over the years for an engine builder and a classic car repair shop. Member here for 24 years! This is the very first car/truck Internet forum I joined. I still used a dial-up modem back then! Last edited by MikeB; 02-06-2021 at 01:55 PM. |
02-06-2021, 01:52 PM | #5 |
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Re: Ignition switch wiring
Also, which terminal was the small red wire connected to on the old switch? Does it look like a factory wire or something that was added?
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Mike 1969 C10 LWB -- owned for 35 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, AAW wiring harness, 5-lug conversion, 1985 spindles and brakes. 1982 C10 SWB -- sold 1981 C10 Silverado LWB -- sold, but wish I still had it! 1969 C10 (not the current one) that I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming. Retired as a factory automation products salesman. Worked part-time over the years for an engine builder and a classic car repair shop. Member here for 24 years! This is the very first car/truck Internet forum I joined. I still used a dial-up modem back then! |
02-06-2021, 04:08 PM | #6 |
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Re: Ignition switch wiring
The small red wire is on the replacement connector. On the connector I removed that spot had the 12 ga pink wire. I think the old connector had been jury rigged due to the splices and black tape on it so I don't trust it as a reference. I can match up wires for every location and color except the small red wire. My truck has one less wire than the connector.
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02-06-2021, 04:17 PM | #7 |
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Re: Ignition switch wiring
Regarding the brown wire, I measured the voltage with the wires cut from the connector, no switch involved.
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02-06-2021, 04:44 PM | #8 |
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Re: Ignition switch wiring
Here is the wiring for the key switch.
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02-06-2021, 05:51 PM | #9 |
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Re: Ignition switch wiring
This gets more confusing every time I work on it. I went ahead and connected all the wires to the corresponding colors on the switch connector. Checked voltage on each lug of the connector. The one connected to the 12 ga red wire is 12.3V, same as the posts on the battery. The lug connected to the 12 ga brown wire now measures 16V. How is that even possible? I checked it several times because I just couldn't believe what I was seeing. I think I'm going to have to trace that wire to see exactly where it goes.
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02-06-2021, 06:08 PM | #10 | |
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Re: Ignition switch wiring
Quote:
If it's an auto-ranging voltmeter, are you sure it's 16 volts and not 16 mv?
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Mike 1969 C10 LWB -- owned for 35 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, AAW wiring harness, 5-lug conversion, 1985 spindles and brakes. 1982 C10 SWB -- sold 1981 C10 Silverado LWB -- sold, but wish I still had it! 1969 C10 (not the current one) that I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming. Retired as a factory automation products salesman. Worked part-time over the years for an engine builder and a classic car repair shop. Member here for 24 years! This is the very first car/truck Internet forum I joined. I still used a dial-up modem back then! |
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02-06-2021, 07:33 PM | #11 |
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Re: Ignition switch wiring
MikeB, you're exactly right. I haven't had that meter very long and I didn't even know it would do that. The mV was so small I couldn't see it without my glasses. Thanks for solving the mystery. I won't be able to work on it tomorrow but I guess the next step is to hook the switch up and see if it starts. I'll just tape up the small red wire for now. Thanks again.
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