Another Low Oil Level Light False Alarm - Chevy Impala SS Forum
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post #1 of 16 (permalink) Old 10-15-2016, 04:03 PM Thread Starter
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Another Low Oil Level Light False Alarm

I have a '95 9C1 and the low oil level light has been turning on intermittently (and falsely) for years. The oil level has never been low on my car. Intermittent gremlins are hard to diagnose. Once, it was on for a few days so I unplugged the connector at the oil level sensor and the light went out. I figured that meant the sensor was bad and I replaced it. Today I read in one of the discussions on this subject in this forum that it works the opposite way. It said that unplugging the connector at the sensor should turn the light ON. Can anybody confirm that? It worked fine for a few months after I replaced the sensor and then the light started coming on intermittently again. Then, a stroke of good luck; the light has been on for a few months whenever the ignition switch is in the run position. So, it is easier to diagnose. With the sensor connector disconnected, I get +12V on one wire and a solid ground on the other. The partial wiring diagram in my Haynes manual shows those two wires go to the powertrain control module (pcm). I presume that is the thing under the air filter. True? So, I know the wiring between the sensor connector and the pcm is fine. The wiring diagram shows one side of the low oil level light gets +12V from gauge cluster whenever the ignition switch is in the run position, and a wire runs from the pcm to the other side of the low oil level light. So, the p.c.m. must supply a ground on that wire when it thinks the oil level is low. I think either the p.c.m. is sending a ground on that wire when it shouldn't or that wire has damaged insulation somewhere and is picking up a ground that way. If I can cut that wire near the p.c.m., I will know which is true. Can anybody help me identify that wire at the p.c.m.? The wiring diagram I have does not give me that information.

Last edited by Frontenac; 10-15-2016 at 04:05 PM.
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post #2 of 16 (permalink) Old 10-15-2016, 04:22 PM
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Check out goldsswagon.com he has losts of wiring diagrams.

Edit i looked it up cuz im bored. Tan wire to pin 27
Looks like it shares common ground with yhe MAF and few other things at front of left cylinder head.

96 BBB 9c1. Rebuilt out of lets just say north of 30 cars.
94 MGR L99. Met a bridge.
92 White L03. Ran to death.
94 OSP 9C1. Lawn ornament.
91 Silver L03. Whales on ice is sad.
94 Black 9c1 clone. Sacrificed.
92 DCM to flat black L03 RMW. Blowed up... twice.
96 Black Woody RMW. Cannibalized.
92 Grey RMS L05. New daily driver.
"i built it one piece at a time, and it didn't cost me a dime!" Johnny Cash

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post #3 of 16 (permalink) Old 10-16-2016, 08:16 AM Thread Starter
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Thanks for the Goldsswagon tip. There is a lot of information there. After looking at the wiring diagram there I think the wire I am looking for is pin 11 on connector B. Instead of cutting that wire, I probably can just unplug connector B from the pcm. Is there any danger of damaging the pcm or anything if I unplug that connector and turn the ignition key to run? If not, then I just need to find out which connector is B. I have not looked at the pcm closely, but I presume the connectors are not labelled. I spent a few minutes poking around the Goldsswagon website and did not find a diagram labeling the connectors. I will continue to search for that information, but If anybody knows and would like to point me in the right direction, I would appreciate it. Also, does anybody know the answer to my first question?

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post #4 of 16 (permalink) Old 10-16-2016, 08:42 AM
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As far as what triggers the light to come on. When I decided to replace the otherwise leak prone and expensive sensor, I just decided to remove it and rely on the dip stick to tell me the oil level.

In removing the sensor and replaceing it witha plug instead, I found that I had to short the 2 wire lead to get the light to turn off. I just used a section of wire formed into a shunt, installed in the 2 wire sensor pigtail and then taped off the connector. No light and no leaks anymore from this area.

================================================== =============


'95 Caprice SS conversion - Bonny Buckets - 96 Column, Shifter and Console - 3.73 Gear and Herter tune - Z/28 Cluster - Blazer OH Console - Green/Pink bushings - Chromed Impala Wheels - Eibach Springs and Bilstein Shocks - Corvette Engine Dress - the list goes on and still more to do...it never ends.
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post #5 of 16 (permalink) Old 10-27-2016, 09:20 AM Thread Starter
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Quote:
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I found that I had to short the 2 wire lead to get the light to turn off. I just used a section of wire formed into a shunt, installed in the 2 wire sensor pigtail and then taped off the connector. No light and no leaks anymore from this area.
Thanks, good to know. My luck ran out and it has gone back to being intermittent now. I tried turning the key from lock to run 10 times while watching the "low oil level" light and six of those times it did not come on for the bulb check when the other warning lights did come on for the bulb check. That suggests an intermittent open between the pcm and the "low oil level" light (pin 11 on pcm connector B) or a defective pcm. I need to cut that wire near the pcm and supply a ground toward the light and watch it for a long time to see if the light ever goes out and then take the ground off and watch the light for a long time to see if it ever comes on. I found this diagram for an "F carline" pcm. I think that means a Camaro but it is probably the same. True? http://shbox.com/1/1995_pcm_conn.jpg I found this diagram for the pinout on the connector, but I don't know if the drawing is the way the pins count on the connector on the pcm or the connector on the wiring harness. They would be mirror opposites. Does anybody know? http://shbox.com/1/1995_pcm_conn_b.jpg There are no labels on pins 11 and 27, which are used for the "low oil level" warning light on B bodies. I hope that just means that Camaros don't have that warning light. If it turns out that this part of the pcm is defective, is this a sign that more important functions of the pcm will start to fail soon?
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post #6 of 16 (permalink) Old 10-29-2016, 09:26 PM
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Eliminating oil level sensor info

FWIW- I'm currently tearing down a L05 1992 Caprice wagon engine to go into a 1994 C1500 and the Dorman oil pan available through Advance Auto for a 1994 C1500 (Dorman 264-100) fits like the original 1992-1996 Caprice and seems to have the same contours as the LT1 pan without the oil level sensor. I can get pics if anybody is interested. Also, anytime you need to check clearance between the oil pump pickup and pan, loosely wad a piece of tin foil and set it in the pickup and set the pan on the bottom of the engine with the gasket missing and you'll get clearance minus 1/16".

I can't answer the "Why" on the oil level sender light being lit. I'm currently dealing with this on the Wife's 95 B4U.

Jim

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post #7 of 16 (permalink) Old 10-30-2016, 09:50 AM
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as was mentioned short out the wires to the oil level pan switch , that is what it is a switch. since we have a dip stick we do not require this idiot light . now if you short out that switch and the oil level light does the same thing then , it is a wiring problem running back to the PCM / PCM connectors etc...

some vehicles made today have no oil pressure indicators just an oil pressure switch that throws an idiot light on the dash indicator[no pressure] as well as a oil level light to show oil is low . no dip sticks . even the transmission has no dip sticks .
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post #8 of 16 (permalink) Old 05-22-2017, 02:29 PM Thread Starter
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Update: I found the time to cut the wire from pin 11 of the B connector close to the PCM and I watched the light for a few weeks and it never came on. That tells me that the problem is not an intermittent ground on that wire. I reconnected that wire and put a ground on pin 27 of the same connector near the PCM. That simulates the oil level sender supplying a ground to the PCM when the oil level is good. Now, the warning light is not lighting except for the bulb check. I will watch it for a few weeks and see if it misbehaves again. I played with the ignition switch some more and discovered that the bulb check does not light the low oil level light unless the ignition switch has been in the off position for about 4 seconds or more. If I turn it off and quickly back on, other warning lights get the bulb check but not this one. I would like to know if other cars act that way. Some here have suggested that the light is not important. It's important to me because my car has a 22 year old aluminum engine oil cooler with mostly aluminum oil lines connecting it to the engine. If any of that aluminum cracks, I want to know about it quickly to save the engine. If it is a slow leak, it won't affect oil pressure so I won't get those warnings until it runs out of oil.
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post #9 of 16 (permalink) Old 05-22-2017, 02:44 PM
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Quote:
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Update: I found the time to cut the wire from pin 11 of the B connector close to the PCM and I watched the light for a few weeks and it never came on. That tells me that the problem is not an intermittent ground on that wire. I reconnected that wire and put a ground on pin 27 of the same connector near the PCM. That simulates the oil level sender supplying a ground to the PCM when the oil level is good. Now, the warning light is not lighting except for the bulb check. I will watch it for a few weeks and see if it misbehaves again. I played with the ignition switch some more and discovered that the bulb check does not light the low oil level light unless the ignition switch has been in the off position for about 4 seconds or more. If I turn it off and quickly back on, other warning lights get the bulb check but not this one. I would like to know if other cars act that way. Some here have suggested that the light is not important. It's important to me because my car has a 22 year old aluminum engine oil cooler with mostly aluminum oil lines connecting it to the engine. If any of that aluminum cracks, I want to know about it quickly to save the engine. If it is a slow leak, it won't affect oil pressure so I won't get those warnings until it runs out of oil.
aluminum lines can leak but how is that gonna happen you hit it with a hammer or rock etc.. now steel lines that is a problem up here in the rust belt.

had my impale 21 years that low engine oil level light never came on LOL... useless ............this low oil light is for owners that are totally ignorant on vehicle maintenance ..

aluminum does not rust out ... the rubber hoses do leak or I should say weep ....
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post #10 of 16 (permalink) Old 05-26-2017, 11:08 PM
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Aluminum does not rust out but it does corrode.
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