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Oil pressure relief valve

Hi there,
Do anyone have a digram where oil pressure relief valve is located in Chevrolet Trailblazer 2007 LT, I’m experiencing High oil pressure and i’ve already changed the oil sending unit but the oil pressure gage still showing high pressure.
Thanks in advance.

Try changing the oil filter. If you recently got an oil change…you may have gotten a bad filter.


Sometimes, they are built into the filter mounting block. It appears the relief is built into the pump housing on the TB-

Before concluding the oil pressure is too high, I’d recommend testing it with a mechanical gauge.

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I’ve just got oil and oil filter changed, also I got the engine flushed, but the problem still the same, the gauge still showing high oil pressure.
Is it possible that the problem is with the gauge itself?

This is the gauge while the engine is running, when it’s off the needle points to 550 kpa, it doesn’t return to zero !!!

Definitely a gauge problem.

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Forgot to tell that when I was changing the Oil sending unit, I found that the wires were exposed at the socket side and twisted on each other I then covered them with electrical tape, is it possible that this caused a circuit short?

That’s a gauge problem. The Trailblazer has only a pressure switch. The ECU then adjusts the gauge based on engine RPMs. In other words, it’s fake display. Yours looks like a common problem with the gauge but it wouldn’t hurt to test the output from the switch first.

EDIT, saw your last post. It’s a switch so shorting should not kill the gauge display. It may not be properly connected so check that first and then the switch action under oil pressure (running).

It’s quite possible the stepper motor controlling the gauge is faulty . . . a common GM problem

there are lots of youtube videos showing you how to replace the motor(s)

and there are lots of vendors who sell those motors

definitely a repair a diy guy could do himself, should the motor in fact be the problem

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Yes it is. Have someone hook up a mechanical oil gauge temporarily to verify that.

The era Chevy that you have has a history with bad stepper motors on the instrument panel, but when the issue is the oil pressure sensor, the sensor fails more often than the stepper motor.

A quick check of the sensor is to turn the ignition switch to the run position without the engine running. If the gauge reads zero with the ignition switch off and max in the run position with the engine not running, then its the sensor.

The bad stepper motors came in batches so generally if you have one bad motors, others will fail too around the same time. So if multiple gauges act up, its the stepper motors. Usually the gauge just stops working.

If the gauge is moving but not in the normal range, the stepper motor could have skipped some gears.

When the ignition switch in the run position without engine running, the gauge points to 550 kpa not zero. So I believe as you all suggested that the problem with the stepper motor of that gauge, but before I move to that direction, I’ll take your advise and check the oil pressure.

Thanks guys for the advises, I really appreciate your concern.

550KPA is 80PSI, I guarantee you that when you engine is not running, your oil pressure is 0 on either scale.

There are some YouTube videos on repairing the stepper motors, but in your case, I think it just jumped a few teeth on the gauge.

Well, the good new is the oil pressure is ok when get it measured by a mechanical gauge, I looked at the cluster fixing videos on youtube, it actually needs some soldering skills of electronic boards otherwise I may ruin it :slight_smile:

Does it also have a low oil pressure warning light? If it does, I’d forget about the gauge.

If you are uncomfortable doing the repair yourself . . . assuming you even want it fixed at this time . . . there are several companies out there, which will replace all the stepper motors in your cluster, if you remove it and send it to them

Google it, you’ll get lots of hits

Luckily, low oil pressure warning appears in the Driver Information Center (DIC).

For the stepper motor repair, I’ll take the board to some electronics workshop to do the soldering work. but for the time being as long as I’m relieved that I the engine doesn’t have a serious problem I can live with the gauge for some time.

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