huskeric

I've read through at least 30 threads about the MY 89+ oil pressure sender/sensor, but appear to have a different problem.

As soon as I turn the key, they oil pressure needle pegs - and never comes down until the car is shut down.

Well, last year on summer break in the 115 temp Vegas heat, the 'insufficient oil pressure' text came on the digi dash. Previously, I presumed the sender was bad due to the pegged needle; however, now it is evident part of the sender is functioning.

I did notice during an oil change the 3 prong sender electrical clip was long gone and shabby looking electrical connectors in place.

I've not yet checked out the 14 pin connector for wiring condition.

So... it is possible for this sender to 'partially fail' if you will?? Or, does this now sound like wiring?

thanks
rick

James Bailey

perhaps both.... the sender has two components a variable resistor and an on off switch..... the simple on off is what sends the low pressure warning the variable drives the gauge.

Mrmerlin

and you could have an issue with lower viscosity oil.

I would suggest to change the oil to Valvoline VR1 20 W 50 Racing oil and swap in a new Mahle oil filter.

Also have the sender connections fixed,
the gauge is mis wired if it pegs when the key is turned on most probable.

OR the 14 pin connector at the hot post has shedding insulation,
and the oil pressure wires are shorting.

FredR

+1 on what Stan says. What oil is in there at the moment?

That oil presure indication system seems very fickle to signal interference. I have a new sender, new wiring back to the 14 pin connector, have pulled the dash panel and checked the connector strip [nice and shiny] and still get the indicator pegged when the motor is switched off. When running the display shows generally sensible characteristic behaviour with occasional twitchy behaviour so something not quite as it should be but dammed if I can find out what to date.

I would pay attention to the low pressure warning light- I do not see that even though I reside in a very warm climate but when the ambient temperature is over 35C in the hot season I do not push the motor too hard for other than very short bursts. At least I have the later style external oil cooler and that is not perfect [I suspect].

Rgds

Fred

Eplebnista

Any time I have a gauge or a light telling me I have low oil pressure, I check it with manual pressure gauge plumbed into the oil pressure sender port. More often than not, my experience is that this confirms that the problem is in the wiring to the gauge or the light. A decent manual gauge is not an expensive tool.

Of course, Stan is also correct to point out that an intermittent low reading under high temp conditions could be from oil viscosity.

Mrmerlin

the easiest thing to do is change the oil especially after running the engine in hot conditions, if the low pressure system has not come on till after the hot run issue then its a good bet the oil has been overheated and it has lost some of its viscosity

martinss

The immediate pegging of the gauge with the key turned, and I assume even without the engine running, sounds like it could be a ground-to-gauge issue in the pod. I had a similar thing on the left side of the pod - the fuel gauge would peg when I turned the ignition on no matter how much gas I had - even with an empty tank. I subsequently found that the temperature gauge would peg if I turned on side and/or headlights. The two gauges share a common ground. The lack of ground was pushing extraneous voltage through the gauges.

I found that the ground pin in the plug that supplies the gauges was pushed out of the back of the plug so it did not make contact with the foil trace. So you might want to check the plug for the right side small gauges

Of course it could be many other things...

Good luck.

worf928

If I recall correctly, low pressure warning coupled with a pegged pressure gauge are the exact symptoms of an unplugged sender for the three-prong senders.

Given, "the 3 prong sender electrical clip was long gone and shabby looking electrical connectors in place" I would start at the plug connections and check continuity to the 14-pin connector.

Whitesands

Having just done a timing belt change plus oil and filter change which meant moving cables by the alternator and filter my oil pressure needle started going from max to min almost at warp speed, then would read normally for a short distance.

Photo is after I removed the wires from the sender and removed what was left of the boots, the insulation just crumbled.

Now fixed and the gauge is back to normal.

FredR

Ivan,

That's nice- presumably you have the older two pin sender- not the later 3 pin one that we cannot get the connector for.

That is the kind of condition things end up looking like if left long enough.

Rgds

Fred

Whitesands

Fred, I guess heat cycles and age is not the best things for the wiring on our cars.

huskeric

thanks all for the insight...

I failed to mention I did change the oil immediately after the digi notice came up. I put in Mobil 20w50 and I think that resolved the viscosity issue...

now, armed with the above info, I need to track down the other issue and will start at the sender and work my way up. luckily, I have a spare gauge set and sender... this should help eliminate possible suspects.

much appreciated.
rick