Oil Pressure reading "0"

[kenmyfam]

Just replaced tranny last week and hoping to get another couple of years out of our 2005 Trailblazer (our tow vehicle) Got about 1 mile on the way to work this morning and noticed that the oil pressure gauge was reading zero !!!! No knocking noises or anything nasty and mechanical sounding though. Drove slowly to the nearest gas station (2 miles) and listened carefully the whole way with the windows open. Topped up oil (1 quart) then drove about 2 miles back home again. Still no nasty noises and vehicle sounds just like it normally does. Thinking maybe sensor unit or similar. Anyone got any ideas ??
Any and all help will be greatly appreciated.
Thank You in advance.

 

[christo829]

If it was the sensor you'd most likely be getting a "Check gauges" alert or the PCM would be sending you nasty messages when it noticed it wasn't getting any data from the sender/switch. You may have fallen prey to a bad stepper motor. If you put the key in and turn to "Run" position, does the gauge twitch at all? They should all go through a calibration step. If it doesn't twitch, then try starting it. If you see no motion at all, odds are it's the stepper motor.

There's a port on the filter housing that could be used to hook in a mechanical gauge if you want to verify pressure.

Good Luck!

Chris

 

[Sparky]

The switch is purely that, a switch. Either on (enough pressure) or off (not enough pressure). The readings on the dash are mostly fabrications.

The switch could have failed, or sometimes you get gunk in there that stops the switch from working. If the stepper is behaving I'd start looking at that switch.

If you actually had no oil pressure the engine would be very unhappy very quickly.

 

[christo829]

I tend to still call the switch on the I6 a sender, even if it's only sending an "on/off" signal. Leftover from putting mechanical gauges in all my previous vehicles... Still wish it was a real one!

When my gauge died, I wasn't sure whether it was the switch or the gauge. I disconnected the switch, and got the "Check gauges" alert. Then I paid closer attention to the gauge itself and realized it wasn't even twitching during the
initial calibration step. Pretty sure sign that the stepper motor is dead, though they can seem to react properly at start up and then fail, which is what my volt meter did. Luckily they dropped at almost the same time, so I only had to pull the dash cluster once...

Cheers-

Chris

 

[Redbeard]

I had the same problem several years back. The sensor was bad, yet I did not have any error codes coming up. Changed out the sensor and went back to 'normal". I wish it were a true pressure gauge and not a simple "on/off"switch and the computer guessing what your pressure is! I suspect without hearing "loud mechanical clunking" you have oil pressure and nothing to worry about.

my 2 ¢
Redbeard
I have changed all my stepper motor prior to this happening and the oil pressure showed back up after changing the sensor.

You may not like guns.
That is your right.
You may not believe in God.
That is your choice.
But if someone breaks into your
home, the first two things
are going to do are…
1. Call someone with a gun
2. Pray they get there is time

 

[kenmyfam]

Much appreciate all the feedback so far. There is a twitch at start up but it then stays at zero once running.

 

[mrrsm]

FWIW…

Brian from “Briansmobile1” produced an unusual approach on Youtube to solving this problem with sketchy Dash Panel Gauge Readings and Dimming Panel Lights by attacking the problem by simply pulling the Cluster and just re-soldering the Solder Pin-Points where the Main Connector interfaces the Cluster Mother-Board… without dis-assembling the entire Cluster Plastics or changing out the White Cluster Gauges first. The critical action starts around 7:30 Minutes and lasts to about 21:00 to view exactly what he is doing with the re-soldering work. Right along with changing out the Old Panel Gauges & Lights for new ones...The problem of having NO OIL PRESSURE on the OPG might also get solved by doing what he well and truly works out on this video:

 

[Mooseman]

Although that video might be useful for someone having the issue described in it (multiple failures, no gauges at all), the OP only has the OPG not working. Since the gauges are all fed from the PCM through the data bus' single wire, if the issue was the plug or wiring, all the gauges would not work, like in the video.

Since the OP's gauges do work, except for the OPG, these are the two steps to diagnose:
- if getting a 0 reading and getting a check gauges/low oil pressure stop engine message, that would indicate that the pressure sender/switch is defective or you might actually have low oil pressure (with accompanying noises)
- if getting a 0 reading but not getting the check gauges/low oil pressure message, then this points to a defective stepper motor.

 

[MAY03LT]

My favorite topic. And by favorite topic I mean I am so burnt out from arguing about how that stupid gauge works that I'm doing something about it LOL. Here's a sneak peek of the fabrication told by the cluster.

If you follow the service info, if the cluster pid for displayed pressure is ok, and the gauge isn't, replace the cluster. For us DIY peeps who don't have the means to read cluster pids, removing the ipc fuse and closely watching the gauge while putting the fuse back in should show you if it's a dead gauge.

 

[kenmyfam]

Well, home from work now (left TB on driveway and shared ride with the wife today) Re checked oil level (OK) then fired it up and as if by magic it is showing oil pressure again on the gauge !!!!

 

[MAY03LT]

Typical sign of a gauge crapping out. The temp gauge in mine does it intermittently.

 

[Mooseman]

Anyway, it's kinda pointless to fix it since it's fake. As long as there is no light, you're good

 

[Redbeard]

Also if you would like extra piece of mind you can send off an oil sample to Blackstone (http://www.blackstone-labs.com/) labs. They will send you a free sample container to fill with oil (or any other fluids, trans, rear end etc.) that holds several ounces of liquid which you then mail back to them. They report back to you EXACTLY all impurities which are floating in your oil. And heck for a couple of extra dollars they will start suggesting how much longer you can travel on your oil. I believe they charge about $28 to analyze your oil and to me it is well worth it. I have been using them for the past 10-15 years and strongly recommend them. Take a look at a sample sheet they prepare for your oil. If any internal parts of your engine are starting to wear improperly it will show up in your oil. Like if you are starting to show an increase of lead in the oil, start looking at bearing problems, or extra liquids (antifreeze) in your oil possible bad gasket and the list goes on. Check them out.
Redbeard
who has about 175k on the TB, and in 2010 gave a 1991nissan pickup with 365k miles to a friend who is still running it with no motor work needed or required.

 

[kenmyfam]

All is still well !!!!

 

[kenmyfam]

And continues to be well. Thanks for all the great help and advice. I am starting to get paranoid watching it now

 

[Redbeard]

An "old" mechanic once told me "why do you want an oil gauge? It's just there so you can watch your engine wearing out".