Oil pressure light wiring?

[Jon Hile]

I recently had to remove the oil pressure/ oil temp gauge and dutifully mapped the wire connections prior to removing the wires. I plugged them all back on and now the oil pressure light does not come on when the ignition switch is in the "on" position (alt. light switch is on). I pulled the gauge and checked the bulb and holder by swapping them with the low fuel bulb holder (same part). The bulb and holder are not the problem. The wiring looks correct. 2 green and white wires on shared plug coming in one side and the single red/black wire coming off the triple red/black plugged in on the oil pressure gauge.
The one suspect thing is I have current on both the red/black wire and the two green/white wires. I "think" I put them all back on correctly and have even checked them agiainst the SC wiring diagrams here on Pelican (diagram 5 part 2) but still no joy. Any other stuff I can check?

[Jon Hile]

Update on related (?) symptoms:

1. Oil Pressure indicator light does not come on when key is turned to "on" position. There is power coming to the bulb and the bulb is showing no resistance (bulb is not burned out)

2. Seat belt warning light is also not functioning (not that I want it to all that much)

3. Parking brake warning light is functioning normally

From what I see on the wiring diagrams these problems should not be related (seat belt/parking brake/oil indicator) but am not sure.

I would think if the pressure switch were faulty the light would come on and stay on. Is this correct?

[Hald]

John -

As you've measured, voltage is applied to the OP indicator via the red/blk wire. With the engine off - no OP, the OP switch should be supplying the ground on the grn/wht wire to complete the circuit and light the light. If you're seeing voltage on the grn/wht wire, with the key on & engine off, then that would indicate that you have an open somewhere between the grn/wht connection at the bulb and the OP switch. Or, possibly the OP switch, itself.

[Jon Hile]

Thanks Mark. I'm beginning to think the switch is the culprit and your message only helps confirm it. That's the one on the front of the engine below the airbox and a PAIN to reach isn't it?

[Hald]

That's correct, John. It's a pain, but eased a lot if you lower the rear of the engine.

[Early_S_Man]

Jon,

Mark's reasoning is correct, but the switch is not necessarily the first thing to check ... those wires in the engine compartment have been known to break internally an inch or so 'upwind' of the Faston connector ...

My suggestion is to support back end on jack stands, then support engine bottom rib with floor jack, loosen both M12 engine mount bolts, and lower engine 2" - 3" ... remove rear passenger-side wheel, and go exploring with a flashlight for the oil pressure switch wire. Securely attach the Faston connector to ground at a convenient place with jumper clip lead, and check resistance to ground at the wire on back of gauge ... lack of continuity would indicate a broken wire, internally. If broken, pull off Faston and find location where break occured. Chop off, and strip wire at 1/2", then trim back to 1/4" where fresh copper present. Install new Faston if sufficient slack, otherwise splice in an extension piece. Functionality of your lamp should be restored.

If wire wasn't broken internally [reported multiple time here at Pelican] ... check switch, and replace if you don't have continuity to ground at terminal.

[Jon Hile]

Thanks Warren,

I'll give it a look later today. (Got some tomatoes to plant before I can play in the garage.)

j

[Jon Hile]

Final (I hope) update. Jacked up the car, pulled the airbox and lowered the engine a couple of inches. The wire to the pressure switch was OK, switch appears to be the culprit. In the process discovered a screw (LARGE) in the rear passenger tire. Looks like I get to upgrade my Dunlop SP8000s.

Having LOTS of fun now.