The Change Oil Light

Is it me, or does that light do more than "flash" in your face until you hit the oil reset button? I change my oil myself, and don't always push the reset button.

Last night, when leaving a party, the oil light was on, and started to flash the check engine light, in which case the car felt like it was running on 4 cylinders, it had a strange feel to it. I shut it off, reset the light, start it back it, and it was purring like a cheetah, read to go.

One time in the past, nearly a year ago, same oil light, same flashing check engine, and same odd engine behavior.

What is this, the idiot light and idiot engine trick to scare the customer? This is a new PCM too since last year!

Did you scan for stored error codes? There is probably at least one stored. The possibilities are almost endless.

" this one time at band camp"

No codes whatsoever. It only dies this when i dont reset the oil light by the button in the fuse compartment. Its as if it wont rev up high at all so it feels very weak.. But when i reset the light, it runs fine again.

Dont know if this is limited to the obd1 model or not, but its very werid.

I had to remove and clean the sensor on my '96:

http://www.wwdsltd.com/files/1996LT1OilLevelSensor.jpg

It's not the low oil light.

I'm talking about "Change Oil" and if I'm not mistaken, that runs on a timer, not a sensor.

Instead of a timer, it's actually a calculation of fuel used, load value (LV8) over a given time, and conductivity of the oil (the sensor).

Oh ok. Well I change my oil regularly, so perhaps I'll look at the sensor.

But why would resetting the light cause it run fine afterwards immediately? Seems like the PCM tries to scare you almost.

When you inspect the sensor, take a close look at the connector and particularly the wiring around it. If the sensor power wiring is grounding, it could affect the PCM. This could also occur if the sensor were shorting internally. AFAIK, the oil condition monitor should have no effect on performance through the programming.

It's not the low oil light.

I'm talking about "Change Oil" and if I'm not mistaken, that runs on a timer, not a sensor.

on the 1996 this change oil LIFE monitor comes on when mileage hits 7500mi max.,the engine load operation, the engine temperature,the oil temperature,and the engine RPM's...that the preprogramed PCM then will set this indicator LAMP.

normally 3000mi to 7000mi the light should come on...

notice that is does not have a sensing ability for debris,,,or contamination...


since you have a 1994 it is possible that this circuit is very different ,,,in that it may effect the operation of the engine...

also there is no sensor,,,,this is data the PCM has stored from vehicle operation...to determine oil life change cycle...


other vehicles GM made had this and your issues are odd..

[quote=evildragon;6031811]Is it me, or does that light do more than "flash" in your face until you hit the oil reset button? I change my oil myself, and don't always push the reset button.

the [change ?]oil light was on, and started to flash the check engine light, in which case the car felt like it was running on 4 cylinders, it had a strange feel to it. quote]

the check engine light is not supposed to be on when the oil life monitor is on...


when this occurs again pull code before engine shut down..

Ok, it did it again today on a grocery trip (it's been about 6000 miles since last pushing the button, which goes to what jcat said), this is exactly what it does.

When I put the key into "ON", not start, and change oil comes up, the electric fans come on as if it's going into field service mode. If I ignore it and drive, check engine starts to flash and the electric fans turn off and on with the flashing of the check engine light.

So, I scanned it. No codes whatsoever.

Turn off, reset oil button, turn on, all lights off like it should be, fans running normal, and performance back.

Remember, the PCM is brand new, and this is the same thing the old PCM did, same exact thing.

Something is strange there. The fans and flashing MIL are not normal. The oil change light may be a cause or just a symptom. I'd still inspect the wiring, and perhaps unplug the sensor just for grins.

The oil monitoring systems on these are varied. The '94s are pretty consistent. The '95s get a little strange and varied, and the '96 models might have had an oil level sensor, oil conductivity probe, a plain oil pressure switch (25036940), or an oil pressure and oil temperature switch (10201491). My '94 has never had an issue, but my '96 had a P0197 but has only the pressure sensor. It turned out that the PCM stored a false code after a battery recharge on a fast charger which generated too high an AC wave contingent in the DC power (heavily pulsed DC). That will scramble a RAM quickly. A reflash of the PCM and everything was back to normal.

Ok, it did it again today on a grocery trip (it's been about 6000 miles since last pushing the button, which goes to what jcat said), this is exactly what it does.

When I put the key into "ON", not start, and change oil comes up, the electric fans come on as if it's going into field service mode. If I ignore it and drive, check engine starts to flash and the electric fans turn off and on with the flashing of the check engine light.

So, I scanned it. No codes whatsoever.

Turn off, reset oil button, turn on, all lights off like it should be, fans running normal, and performance back.

Remember, the PCM is brand new, and this is the same thing the old PCM did, same exact thing.

the wiring to the dash instrument panel and connector should be checked...this is where things could be somehow cross connected/shorted to another circuit as well as the internal dash panel ...

My '94 has never had an issue, but my '96 had a P0197 but has only the pressure sensor. It turned out that the PCM stored a false code after a battery recharge on a fast charger which generated too high an AC wave contingent in the DC power (heavily pulsed DC). That will scramble a RAM quickly. A reflash of the PCM and everything was back to normal.

thanks for that info on the battery charge issues...when the battery needs a full charge I am going to disconnect the negative terminal to aviod this...

Hmm, I do have some funky issues with the dashboard. The digital dash's odometer's numbers sometimes on a cold start, appear "ghosted" in that one digit may appear 2 digits to the side dim, corrupting that number on the display.

So for example, if my trip was say 60.9 miles, the odometer may read 6 60.9 sometimes, or if a number is in the place of the ghosted number, weird characters forum unless I hit the clear plastic on the dashboard where the problem clears up.

Hmm, I do have some funky issues with the dashboard. The digital dash's odometer's numbers sometimes on a cold start, appear "ghosted" in that one digit may appear 2 digits to the side dim, corrupting that number on the display.

So for example, if my trip was say 60.9 miles, the odometer may read 6 60.9 sometimes, or if a number is in the place of the ghosted number, weird characters forum unless I hit the clear plastic on the dashboard where the problem clears up.

these dash switches that change the trip/ reset trip odometer ETC>>>
have been known to cause dash circuits to get broken when they are pushed too hard..the dash is not very strong,,and some that have opened the odometer have found the circuit in need of soldering etc...


on my 96 I had to solder the resistors that power the odometer,,as my odometer was fading away....I don't use the trip switches on the dash ..

So, I found out what it is.

Limp Home Mode. For some reason, when that change oil light comes on, it triggers Limp Home Mode, and for the PCMs I've had, it appears to be part of the programming to flash the check engine light if ignored for too long..

So, I found out what it is.

Limp Home Mode. For some reason, when that change oil light comes on, it triggers Limp Home Mode, and for the PCMs I've had, it appears to be part of the programming to flash the check engine light if ignored for too long..

where did you get this information ?

via tuner software..

via tuner software..

I looked up "VIA TUNER SOFTWARE" came up with nothing..!

because that was a phrase, not a product

I went to a local mechanic which ran tuning software on my PCM, and found it was programmed to enter limp home mode when the change oil light is on for so many miles past due...

This PCM was purchased at AutoZone, whom of which did the initial flash. The PCM before this one was also purchased from AutoZone, so they likely flashed it the same way.

because that was a phrase, not a product

I went to a local mechanic which ran tuning software on my PCM, and found it was programmed to enter limp home mode when the change oil light is on for so many miles past due...

This PCM was purchased at AutoZone, whom of which did the initial flash. The PCM before this one was also purchased from AutoZone, so they likely flashed it the same way.


I wonder if this is a GM or the PCM repairer software that changed this..I have no reference material that makes reference to it..placing the vehicle in limp mode because the change oil LT is on...

I'll have to ask what program the mechanic used to see. I remember it had hexadecimal view of the flash also...