Alt and Oil Light on in Accessory Only Key Position

Charging, starting, lighting, gauges, HVAC

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UKPR1
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Alt and Oil Light on in Accessory Only Key Position

Post by UKPR1 »

Finally coming to the end of my wiring woes. Trying to square away the last few head-scratchers...

So when I turn the engine on, the oil and alt light glow bright, but only the oil light goes out completely. The alt light continues to faintly glow. Even revving the engine has not affect, so it's it my plan this week to test the output of the alternator and if good, replace the voltage regulator.

What's confusing, is that when I put the key "back" one click, the oil and alt lights on the cluster come on. I wired in a new pigtail and ignition switch, as well as an entire new fuse block...did I wire something incorrectly?

Geoff
UKPR1
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Re: Alt and Oil Light on in Accessory Only Key Position

Post by UKPR1 »

Ignitionswitch.jpg
So according to the schematic, the "permission" for the alternator and oil lights to come on, comes from a black/green wire (wire 297) that comes from terminal C on the ignition switch and comes on in the coil and accessory position only. It shouldn't be possible to have the lights illuminate in this key position AND in the Accessory only position, even if I mis-wired something.

Any ideas what might be happening here? Bad Switch?
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sargentrs
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Re: Alt and Oil Light on in Accessory Only Key Position

Post by sargentrs »

That's what I'd try.
Randy
1970 F100 Sport Custom Limited LWB, 302cid, 3 on the tree. NO A/C, NO P/S, NO P/B. Currently in 1000 pcs while rebuilding. Project thread: http://www.fordification.com/forum/view ... 22&t=59995 Plan: 351w, C4, LSD, pwr front disc, p/s, a/c, bucket seats, new interior and paint.
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UKPR1
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Re: Alt and Oil Light on in Accessory Only Key Position

Post by UKPR1 »

Got a new ignition switch on order, but I'm wondering if it was necessary and here's why...

...When you look at the wiring schematic: in particular at the ignition switch, when the key is in the 11 o'clock position (acc only) it should only provide power to terminal A. However, when you look closely at the ignition switch diagram, there seems to be a jumper or some kind of connection between terminal A and the terminal in the 1 o'clock position (under the word "OFF" in the switch diagram). If this is true, then the 1 o'clock terminal also receives power with the key in the 11 o'clock position which gives power to wire 297 to wire 30 and then light the oil and alt lights.

Can the electrical gurus out there tell me if my way of thinking is wrong, or if I'm right...does everyone's oil and alt light illuminate with the key in the ACC position???

Thanks

Geoff
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beejaytx225
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Re: Alt and Oil Light on in Accessory Only Key Position

Post by beejaytx225 »

My oil and alt lights come on with my key in the acc (11oclock) position.
1968 F-100 Ranger LB
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Past Ford's: 1994 Ranger, 2008 Ranger, 1991 Ranger, 1985 Mustang, 1968 SB Custom Cab F100, 1998 Explorer.
Current Ford's: 2011 Ranger, 2006 Expedition, and of course Bethany :)
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Re: Alt and Oil Light on in Accessory Only Key Position

Post by Ford-f100-1972 »

Mine both light up with the key on ACC on my '72 also. I had a '67 years ago and it was the same way.
UKPR1
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Re: Alt and Oil Light on in Accessory Only Key Position

Post by UKPR1 »

So...I'm normal???

I'm normal! Wait till I tell the wife that I'm normal!

Thanks gents!!
zgerbic
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Re: Alt and Oil Light on in Accessory Only Key Position

Post by zgerbic »

As others have pointed out, this is normal operation. My new to me 69 truck is the same. I was just wondering about this yesterday while replacing the radio. It seems that since accessory and ignition are the same, both will pull down the battery at the same rate, and the coil is energised in both positions which I think is wrong.

However after looking at the schematic, I can see how three cuts and three jumpers would make the ignition switch work more like you would expect it. These changes would make everything be powered up as in the current wiring when the ignition switch is in the right position. The left position, accessory, would not power up most of the running related functions. Some of these would be temp gauge, gas gauge, oil pressure light and coil. The windshield wiper/washer could still be used in accessory position.

Next time I have the gauge assembly out, I am going to rewire my harness to make the ignition switch operate the way I want it to. I will try to get some time to document this change as I bet others would like to fix this.

Just a question to other forum members, what would you expect to be on in the accessory position?

Regards
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