need help with low oil pressure [Archive] - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

: need help with low oil pressure


philbilly
08-25-2007, 11:40 AM
Here is what happened. My wife was doing some running around town and had stop at the bank while she was sitting in line when the check gages light came on she does everything normal. Then DIC flashes OIL PRESSURE LOW, but the gauge reads 40psi. Seconds later the engine shuts off she turns the truck off and then restarts it with no lights or dic warnings. The truck has about 55,000 miles on it and the oil is full if that helps. Anyone else have this happen and what would be the fix?

RayVoy
08-25-2007, 05:38 PM
So the question is: do u believe the DIC or the gauge? I would get the oil pressure checked.

philbilly
08-25-2007, 06:29 PM
gauge seem to be working fine

Bearcat
08-25-2007, 07:00 PM
Haven't seen it with my truck, but I have seen oil gage fluctuations on other vehicles. I would believe the gage before the DIC. Most likely, the problem is with an electrtical connection rather than the oil pressure. i would just keep on eye on it for a repeat.

philbilly
08-26-2007, 10:13 AM
this is the 2nd times this has happened the first time everything flashed and then went away with no stalling. I'm wondering if the pcm reprogramming that pcmforless claims it needs while fix it.

RayVoy
08-26-2007, 11:53 AM
this is the 2nd times this has happened the first time everything flashed and then went away with no stalling. I'm wondering if the pcm reprogramming that pcmforless claims it needs while fix it.I think Bearcat is right, it's an electrical problem. But, I don't think it's a pcm problem. If the DIC is wrong and the gauge was right (when u looked at it) consider this: and intermittent loose connection would cause the DIC to trip an alarm and the oil gauge to pulse. When the open circuit condition closed (maybe 1 sec later) the DIC is still tripped, but the gauge is happy and back to normal. I'd look at a loose connection in the oil sending unit circuit.

emti309
08-26-2007, 01:50 PM
:iagree: sounds like a sending unit problem somewhere

philbilly
08-29-2007, 08:40 PM
update ok it happen today and I was in it went it happened. we were sitting in a parkinglot tthe truck started to stall the gauge light came on wife tapped the gas and everything was fine.This was the 2nd time today it happened when sitting still. so now what do I do take it to the dealer and tell him to let it run until it stalls?

RayVoy
08-29-2007, 08:46 PM
So, a s I read ur last post, u don't have an oil pressure problem. You have a stalling problem. The falling oil pressure is a result of the slow rpms. The oil pump is driven from the engine, if the engine is not turning fast enough, the pump won't turn fast enough.

You need to get the throttle body cleaned. Try a search, there is a ton of info. There is also an article on cleaning the tb.

philbilly
08-30-2007, 05:07 PM
cleaned the TB and flushed the trans last week. I think its a stalling problem too that's why I fell that it's the pcm thing I was talking about.

RayVoy
08-30-2007, 05:30 PM
Ok, generally a stalling problem is fuel related (but of course, it could be a ton of other things). As u know, the throttle body is an air regulator. The fuel is delivered through the injector solenoids. These could be dirty. Flushing with a can of cleaner dumped into the gas tank might help.
Could also be a vacuum leak, check all hoses for cracks or breaks.
Most of the other things, spark -- exhaust should throw a code.

philbilly
08-30-2007, 05:53 PM
well some lucas oil injector cleaner or some sea foam motor treatment was my next step

ilikemy3s
08-30-2007, 06:05 PM
Also just to elimite any cause .. Bad air filter .. bad fuel filter or bad tank of gas ?

Super 88
08-30-2007, 06:12 PM
:iagree: with all the above, but didn't the 04's have a TSB for stalling, that requires the PCM be reflashed? If you haven't had this done maybe that is your problem.

philbilly
08-30-2007, 07:52 PM
It has newer fliters as for the gas I can't say?

philbilly
09-05-2007, 07:44 PM
well the dealer checked it out and everything was up to date. the only thing they and gm could tell me was the sending unit may be sticking and i may want to replace it or try some seafoam treatment. one thing he told me is that the oil gauge is just a reading from the pcm not an actual reading.

tjarkmentos
10-29-2007, 05:27 PM
I have had the same problem with my 04 Envoy for the couple of years I have owned it. Bought it with 35K miles on it and now have 80K. It stalls only when not under any load e.g. at or coming to a stop. I have cleaned the TB, religiously use Techron, new spark plugs, maintain oil very well (I'm in the oil manufacturing business) and I still have the problem.

Has anyone else experienced and fixed this issue?
Should I replace the Oil Pressure Sensor?
Or is it the PCM?

Thx,

Tyler

HardCore
02-07-2008, 12:57 PM
My 03 is doing the exact same thing. Anyone know what the casue if this is?

philbilly
02-18-2009, 07:01 PM
bad oil sending unit. Change mine and no problems since

JTH
07-09-2010, 09:49 PM
My 03 did this today...When I was backing the jet ski down the ramp. It beeped 3 or 4 times, flashed OIL PRESSURE LOW, died, and then said STOP ENGINE! The oil pressure gauge was sitting on 0 and the Check Engine light came on... It started fine and the oil pressure gauge went back to normal and the check engine light went off... Is it ok to drive? Because I'm about 50 miles from home and don't wanna get stuck halfway there...:bonk:

JTH
07-09-2010, 09:58 PM
Ive had it die 3 or 4 other times, but it just turned off & started right back with no warning lights or anything...

Blazernut
07-09-2010, 10:08 PM
My 03 did this today...When I was backing the jet ski down the ramp. It beeped 3 or 4 times, flashed OIL PRESSURE LOW, died, and then said STOP ENGINE! The oil pressure gauge was sitting on 0 and the Check Engine light came on... It started fine and the oil pressure gauge went back to normal and the check engine light went off... Is it ok to drive? Because I'm about 50 miles from home and don't wanna get stuck halfway there...:bonk:

If it is the pressure sending unit it is fine to drive. Just check it out and make sure it all gets reset when you restart. Always check the dipstick first.

RayVoy
07-10-2010, 05:25 PM
Always check the dipstick first.Yep, your first check MUST be the oil level.

The second check, is to have the oil pressure checked.

If both are good, change the sending unit (GM now calls it the oil pressure sensor).

Just checked your profile is see what you have for an engine. The sensor, on the 4.2 is above the oil filter.
Remove the filter and it is easy to see and change.

This BTW, is a common fault, a lot of us have had to change it.

awer25
07-10-2010, 07:16 PM
Yep, your first check MUST be the oil level.

The second check, is to have the oil pressure checked.

If both are good, change the sending unit (GM now calls it the oil pressure sensor).

Just checked your profile is see what you have for an engine. The sensor, on the 4.2 is above the oil filter.
Remove the filter and it is easy to see and change.

This BTW, is a common fault, a lot of us have had to change it.

I think I may have the same problem - I've seen "Oil Pressure Low" a couple times on the DIC, but only when I just start the engine. I just changed my oil too (~1000 miles ago)- any idea how much I'll lose by just pulling off the filter? I'm hoping not too much since the filter is above the pan.

Also, what is the part number for the OEM switch? I've seen D1838A, D1843A, D1846A, 12573107, and 12614969 which are all around $25. It seems some are for a light and others for a gauge. I know I have a gauge but I think I have a light too.

the roadie
07-10-2010, 07:58 PM
compnine.com lists the switch as item 420 in this view:

GM #12590793
ST1(LL8) SWITCH,ENG OIL PRESS(ACDelco #D1838A)

awer25
07-11-2010, 05:39 PM
compnine.com lists the switch as item 420 in this view:


Yeah I saw that, but since a few model #'s show as correct I just ordered them all and will return the others that don't fit :D

Daddy Mitzo
07-11-2010, 11:36 PM
I had the same exact problem, all you need is to change is your oil pressure switch/sender and that's it. I started having this problem in my 05 envoy a few weeks ago, and stalled on me a couple times a day I changed the switch a few days ago and no problems since. A 30-50$ piece and half an hour labour and you're good to go(when buying the switch you must mention that you've got the gauge and not the light) than you've got 2 choices standard or ac delco, I went with the ac delco

JTH
07-12-2010, 01:05 AM
Thanks guys! I'll get it done as soon as I get back home

guberot
07-17-2011, 03:22 PM
:) awesome website. I had the same problem as the OP. I was able to find the oil pressure sensor and it was leaking. I replaced it with a new one and everything is back to normal.