Oil light stays on

[plumber452]

Hello All
Just got through doing an LS swap on my 69 step side and it's up and running fine. My problem is my oil light won't shut off until I start the engine. I installed a new sending unit and still no luck. Initally When I would wiggle the red wire, which according to the wiring diagram should be pink, on pin 7 of the cluster harness connector, the light woul go on and off. That pin along with a few others stay hot regradless even with the key out of the ignition. I pulled the connector out and cleaned evrything but the light stays on. But now when I wiggle the wire the light doesn't flicker, it just stay on.
If i disconnect the wire from the pressure switch the light goes off. Any thoughts?

Thanks

[dmjlambert]

For cluster harness connector do you mean the plug that plugs directly into the back of the instrument cluster? The pink wire is only hot when the ignition switch is in the on or start position. The oil sender will be grounded to complete the circuit and light the bulb whenever you have low oil pressure or when engine is off.

If the wire is red going into the instrument cluster, I suggest trace that wire and see where it's coming from, because it should be pink. Red wires in the wiring bundle generally mean hot all the time, which you don't want.

Check that on the back of your ignition switch the pink wire (or wire that is in the supposedly pink position) has voltage only when key is on. Ignition switch turns on the voltage, then voltage travels to the fuse box where it runs through the fuse and the pink wire continues from there to the instrument cluster, travels through the bulb, then to the oil pressure sender. The oil pressure sender may or may not complete the circuit to ground and light the bulb depending on whether you have oil pressure.

[plumber452]

Thanks I will check that. Yes I' m referencing the harnes that plugs into the panel. I did have to tie into the pink wire on the ignition switch as part of the LS swap so?????
Also, prior to posting my original question i disconnected the battery. Just now I went back out connected the battery. And now the oil light doesnt come on at all, not even grounding the wire from the pressure switch to the battery ground.
Again, thanks

[plumber452]

Just checked again. The wire I thought was red is in fact pink, after I removed 51 years of crud off of it. And, the oil light is back on. As part of the LS swap I ran a wire from the stand alone LS harness to the pink terminal on the ignition switch which activates the ignition start relay in the LS harness. I thought that it was odd that I have 12 volts at the instrument cluster with the key out of the ignition. As you can tell electric is not my strong suit.

[dmjlambert]

Any by the way, that pink wire from the ignition switch also splits off and goes to the engine compartment, normally to power the ignition coil. Make sure you're not backfeeding voltage into that wire from your engine. I don't know the details of LS engines, whether they would make use of that wire for something, or not.




Here's the whole wiring diagram that I use:
http://67-72chevytrucks.com/vboard/s...49#post7809749

[dmjlambert]

You and I were typing at the same time. So, I would look closely on how voltage is getting onto that pink wire. You can disconnect the bulkhead connector to see if voltage no longer comes onto the pink wire with key in the off position. If disconnecting the bulkhead connector makes the light go out, that means something in your engine is backfeeding voltage onto the pink wire, instead of using voltage from that wire. (or if you ran a separate wire bypassing the bulkhead connector and went directly to the ignition switch pink wire position, disconnect that and see what you get regarding the voltage on that pink wire when switch is off).

[plumber452]

You were spot on!!! When I tied the pink wire from my stand alone harness into the pink terminal on the ignition switch I didn' t tie the pink wire that had been on the ignition switch back into the ignition switch thereby eliminating power to the instrument cluster. And to add insult to injury I had tied one of the battery terminals on the ignition switch into the pink wire that feeds the fuse panel as you described. That explains the constant 12 volts I was seeing at the cluster.

Again, I can't thank you enough. I have been chasing this for two days now.

Thanks,
Everitt

[dmjlambert]

Good deal, glad we got it. I would love to see pictures of your truck, and I know others would love it as well. If you get a chance to make a post in the main 67-72 pickups section, you can show off there. When you are making a post, if you have a Go Advanced button below where you're typing, that is what you use to post pictures. It will expose the Manage Attachments button where you can upload some pictures.