Oil Pressure Lamp Won't Turn On Even With Good Bulb

[afskwarek]

Hi,

I worked on swapping my gauge lights with leds on my 99 sl1 and noticed an issue after I got done. Upon the ignition on, dash lights test, all my warning lights etc were good except the oil pressure light. It has a good bulb. I switched around the bulb in case polarity was wrong. Still didn't light up. Maybe I damaged something? To test that, I even swapped the gauge cluster with a spare one I had on hand. Oil pressure light still wouldn't light up, and I made sure that one had a good bulb too. Normally, wouldn't really care. But if there's ever an issue with oil pressure, I'd certainly want to know. Really not sure why it's not coming on.

[fetchitfido]

What happens when you unplug the oil pressure sensor?

[Waiex191]

Isn't the sender a normally closed switch? So if you unplug it and short to ground the light should be on.

http://www.saturnfans.com/forums/sho...&postcount=269

That would check the circuit excluding the sender.

[fetchitfido]

I've had it come unplugged a few times scaring the...oil...out of me with the red "change engine soon" light coming on, but yes the next step after unplugging is grounding to check the ground leg of the circuit.

I'd have to dig further to see where the power leg comes from.

[afskwarek]

Follow up, yeah I tried unplugging the sensor. Even plugged it in to another sensor and let it hang loose to simulate a lack of oil pressure. Light still won't come on.

[Waiex191]

Originally Posted by afskwarek

Follow up, yeah I tried unplugging the sensor. Even plugged it in to another sensor and let it hang loose to simulate a lack of oil pressure. Light still won't come on.

Take the wire off the sensor and ground it to the block to simulate loss of oil pressure.

[afskwarek]

Originally Posted by Waiex191

Take the wire off the sensor and ground it to the block to simulate loss of oil pressure.

I apologize. My electrical knowledge pretty bad. Please correct me if have trouble following. So, cut the negative wire before the connector and attach it to the block? While keeping the sensor attached?

[billr]

Do not cut the wire, slip a small wire (paper clip?) into the harness connector and touch that "probing" wire to ground. I have no schematic showing that circuit, so cannot confirm which wire to be grounded.

[Waiex191]

Like Bill said - a paper clip or something. Here is the schematic of the switch. The other side goes to the wire that goes hot with the ignition.

[afskwarek]

Originally Posted by billr

Do not cut the wire, slip a small wire (paper clip?) into the harness connector and touch that "probing" wire to ground. I have no schematic showing that circuit, so cannot confirm which wire to be grounded.

Alright. Here's what I did. No changes. Hopefully, I did it right.

https://ibb.co/ckGqD6y

[billr]

Did you take some strands off the big wire you used, so that it could reach all the way in and touch the connector contact? And, it is going into the position for the TAN wire?

If the answer is "yes" to both, then that looks fine.

You should also try measuring voltage from that TAN wire to ground (key-on). There should be some voltage there, probably 5VDC. Be sure to use a multimeter, a test light may be too much load to give an effective test of that signal circuit.

[fetchitfido]

Totally missed that OP put LED's in. L-ight E-mitting D-iode. Diode = electrical shunt that basically means polarity matters.

The cluster bulb sized LED usually doesn't have polarity marked and even if it does...the cluster itself isn't clearly marked. If it doesn't work one way, flip it to the other. If it doesn't work the other way either then carefully screw with the 2 metal contact tabs until it works or try one of the other bulbs.

[toggenburg]

OP: stated "It has a good bulb. I switched around the bulb in case polarity was wrong. Still didn't light up."
So, might be a bad LED.

[laser3kw]

OP should put the original OEM bulb (not LED) back in the oil pressure slot and see if it functions normally.

[afskwarek]

I tried about half a dozen leds, switched them around for polarity. Also tried about half a dozen regular incandescents, with two different clusters. Didn't come on with anything.

[afskwarek]

Originally Posted by billr

Did you take some strands off the big wire you used, so that it could reach all the way in and touch the connector contact? And, it is going into the position for the TAN wire?

If the answer is "yes" to both, then that looks fine.

You should also try measuring voltage from that TAN wire to ground (key-on). There should be some voltage there, probably 5VDC. Be sure to use a multimeter, a test light may be too much load to give an effective test of that signal circuit.

To answer your first paragraph. Yes for both. I did get a multimeter (set to 20dcv) and touched negative probe to block, and positive probe to the connector, while I had someone turn the ignition to run for the lamp test. I did not detect any voltage.

[Waiex191]

Originally Posted by afskwarek

To answer your first paragraph. Yes for both. I did get a multimeter (set to 20dcv) and touched negative probe to block, and positive probe to the connector, while I had someone turn the ignition to run for the lamp test. I did not detect any voltage.

When I look at the circuit I'd say it should be 12 volts. I don't think we have any 5 volt sources.

Since you did not see any voltage, there is an open somewhere. Either the wire, panel, bulb (which seems like you have tried a few), or some other connector.

[billr]

The MAP, TP, ECT, IAT, and EGR sensors are all powered from the 5V supply in the PCM. Still, since it is neither 5V or 12V (either is a candidate), then that end of the circuit needs to be checked; no argument there!

[afskwarek]

Originally Posted by Waiex191

When I look at the circuit I'd say it should be 12 volts. I don't think we have any 5 volt sources.

Since you did not see any voltage, there is an open somewhere. Either the wire, panel, bulb (which seems like you have tried a few), or some other connector.

Alright. I have the shop service manual disk and have looked all over and haven't found the schematic that includes the oil pressure switch, figured that would help. Any idea where I can find it? Cause I didn't see it in the instrument cluster schmatics. Other than that, what should I look for now?

[Waiex191]

Originally Posted by billr

The MAP, TP, ECT, IAT, and EGR sensors are all powered from the 5V supply in the PCM. Still, since it is neither 5V or 12V (either is a candidate), then that end of the circuit needs to be checked; no argument there!

Thanks, I did not know that about the 5V. From the schematic the bulb is lit by 12V.