The Stovebolt Site Forums The Shop Area The Electrical Bay Wiring 'Idiot' lights.

Having recently installed my wiring loom and guages, I was wanting to wire in oil and generator 'idiot' lights in my dashboard.
For the oil light do I have to go through the oil sender circuit to 'extinguish' the light when oil pressure is sensed?

How is the generator light wired to go out when charging starts?

Any help/input/schematics would be much appreciated....

Yes, one side of the oil light goes to a switched hot, the other to the oil sender.

The generator light also gets a switched hot on one side, the other side gets wired to the generator A (armature) terminal.

THIS wiring diagram for a '57 car uses "idiot" lights and generator.

Hope that helps ya.

Thanks Waldo, by "switched hot",I assume you mean an ignition controlled live feed?

Yes, the ignition voltage that goes to the coil would be sufficient to power the warning lights. Both lights would need to have 2-wire connections without a socket ground. The oil pressure light is grounded by a switch that senses oil pressure and grounds at any pressure below about 7 PSI. On a 10-SI GM alternator, the ground wire for the warning light is connected to the #1 blade terminal on the perimeter of the alternator.
Jerry

Uh oh, sorry for the confusion. I was thinking generator when I said to wire one side of the "GEN" light to the A of the gen. I remember now you have a V-8 conversion and are most likely running an alternator, so wire it like Hotrod said.

Yes, a switched hot would be any source that has power when the key is on.

Regards

Sorry Waldo,I should have mentioned it was an alternator.

Thanks as well Jerry,if I remember correctly there's a sender screwed into the left hand side of the block below the headers,is that oil or water?
Sorry,I should have said, it's an '81 350 small block.

The oil sender on a smallblock is in the rear by the distributor.

there is a second oil sender port above the oil filter

That's the one i've used for the gauge sender,I just wondered if there was another port,but it looks like complexvariable just answered that one.
I have a look tomorrow.
Thanks guys.

Some small block V-8's have the pressure port above the oil filter, others don't. If not, a T fitting beside the distributor will allow a pressure gauge sender and an idiot light switch on the same pressure port. Very early model small blocks had a pressure port at the front of the block that the remote oil filter used on the 55 models, and the port was there through the early 327's. I used to install an idiot light switch in that port set to 20 PSI on my race engines to let the driver know about an oil pressure drop before it wrecked the engine. We saved a couple of $15,000.00 engines with a $20.00 switch.
Jerry

Thanks again Jerry, I have the gauge sender installed at the distributor,and things are a tad tight in there.
Do you think I could I drill and tap into the top of the existing elbow for the extra sender,or would you recommend a completely new T piece?

I'd suggest a fitting called a "street T", which has one male thread and two female threads. Screw the tee into the existing fitting that's installed in the block, and use its two female threads to mount the pressure sender and the grounding switch at a 90 degree angle to each other.
Jerry

There are combination switches with both built in so no tees required, much more compact and better looking.

Would you happen to have a part #?

Also,can you recommend where you can buy such a part?

The FLAPS guys here are nothing short of useless unless it's a modern 'Eurobox'.....

No part number, I just know on my old Porsche with VDO gauges had one, seems like I got it at BAP/Geon, not sure they're around anymore. Google is your friend. Or try Summit or JEGS.

I wonder if the resistance range of that sender would match whatever gauge is installed in the dash? The gauge might show a reading, but I'd suggest checking it with a mechanical gauge to see if the pressure reading is accurate. Not all sending units will be compatible with all dash indicators unless they're calibrated to work together.
Jerry

Jock, maybe this will help if you didn't get the alternator wiring sorted out. http://s1109.photobucket.com/albums...on=view&current=Alternatorwiring.jpg

For the oil gauge you can use an 1/8"npt "T" and put a short nipple on the center leg and sensors on each side. That is what worked for me, anyway. I am using an HEI on my 350, though.

keep us posted,

Les

Thanks Les,
To be honest i've not had much garage time recently (back problems)
I've got some time off work this week and i'm planning some much needed 'stovebolt therapy'.
As previously mentioned it's real tight at the sender/firewall but I'll check out your suggestion re; the oil switch.

jock,,

try stafford vehicle components

they do allsorts of kits and bits including senders ant tee piece,s

some of the manky monkey motors lot use them and say the service is good

Thanks Spanners,will do

jock..
just another thought worth noting as i,v recently solved some one,s niggling problem

when fitting ,,idiot,, lights.
if you use LED lights the ign warning light will need a resister wiring in with it otherwise it wont have enough resistance to exite the alternator cuasing no charge
i know someone who has just fitted two new alternators on a hotrod project
when it was the LED that was caursing the problem..

Good point Spanners,thanks for the heads up.
I've heard of similar problems with LED indicators(turn signals) not flashing.

BTW Manky monkey motors....Care to expand on that?
I've not heard that expression before.....