Oil level light wiring at the cluster
01-09-2019, 05:05 PM
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Racer
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Oil level light wiring at the cluster
I am puzzled. I am trying to decipher what's going on with the oil level warning light in the instrument cluster. I've gone over multiple factory wiring diagrams, and they all seem to be slightly different, but so far none of them seem right. Or at least, I can't make it work like I think it should.
The sensor itself in the oil pan is normally closed, so under normal circumstances its a short, and when the oil falls below some level, the little floaty guy drops, and the switch opens. Then I believe it winds its way through some wiring and connections and goes to the dash. One diagram I have says it comes in on pin 15 of the A plug on the back of the instrument cluster, goes to "line" 4 of "Additional electric in Instrument Cluster" then goes back out on line 6 and on to the indicator light (#20). Since the other side of that indicator has 12V on it, it would have to be GND, effectively reversing the switch behavior - GND when the level switch is open, and floating when the level switch is closed. This is extra confusing because the line order indicated on the diagram is 4-1-2-3-5-6-7-8. What I think is line 6 to the low side of the indicator light shows a short, so it seems like at least that part of the diagram is correct - the pull-to-ground for the indicator comes out on line 6.
A different diagram I have indicates that the switch is connected to pin 15 on plug C, which then goes to line 10 on the "Additional electric in Instrument Cluster". However, that diagram does not show any further connections from there, and it doesn't even identify an oil level warning light as an indicator light.
Right now the cluster is outside of the car, and I have a setup that sends power (and GND) to it. When I switch power on, the voltmeter registers properly. The main "!" light also comes on, as does the oil level warning light, so it would seem that the circuit is actually working properly. However, I have been unable to do anything to get the oil level light to turn off. My assumption is that when the correct pin on the cluster connector is grounded, the light should turn off. However, I've yet to achieve that, and I'm hesitant to just start grounding every single pin for for fear of inadvertently shorting something out and frying part or all of the cluster.
So, anyone have any experience with this? Where have I gone wrong or what am I misinterpreting in the diagrams? '87 turbo btw. Thanks for any help!
Haven't posted here for ages and never really posted a lot even back in the day, but still playing w/ 944s!
The sensor itself in the oil pan is normally closed, so under normal circumstances its a short, and when the oil falls below some level, the little floaty guy drops, and the switch opens. Then I believe it winds its way through some wiring and connections and goes to the dash. One diagram I have says it comes in on pin 15 of the A plug on the back of the instrument cluster, goes to "line" 4 of "Additional electric in Instrument Cluster" then goes back out on line 6 and on to the indicator light (#20). Since the other side of that indicator has 12V on it, it would have to be GND, effectively reversing the switch behavior - GND when the level switch is open, and floating when the level switch is closed. This is extra confusing because the line order indicated on the diagram is 4-1-2-3-5-6-7-8. What I think is line 6 to the low side of the indicator light shows a short, so it seems like at least that part of the diagram is correct - the pull-to-ground for the indicator comes out on line 6.
A different diagram I have indicates that the switch is connected to pin 15 on plug C, which then goes to line 10 on the "Additional electric in Instrument Cluster". However, that diagram does not show any further connections from there, and it doesn't even identify an oil level warning light as an indicator light.
Right now the cluster is outside of the car, and I have a setup that sends power (and GND) to it. When I switch power on, the voltmeter registers properly. The main "!" light also comes on, as does the oil level warning light, so it would seem that the circuit is actually working properly. However, I have been unable to do anything to get the oil level light to turn off. My assumption is that when the correct pin on the cluster connector is grounded, the light should turn off. However, I've yet to achieve that, and I'm hesitant to just start grounding every single pin for for fear of inadvertently shorting something out and frying part or all of the cluster.
So, anyone have any experience with this? Where have I gone wrong or what am I misinterpreting in the diagrams? '87 turbo btw. Thanks for any help!
Haven't posted here for ages and never really posted a lot even back in the day, but still playing w/ 944s!
