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Discussion Starter · #1 ·
So have a 02 Dakota with 4.7 and I have already changed oil sensor twice, changed oil pump timing and pickup tube and still having issues with light at low rpm or stops once motor is warm. I plan on changing cluster this weekend but I am at a lost now. Is there anyway to bypass that pesky oil guage and put mechanical gauge on? Please help im losing my mind!!
 

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I don't think the cluster is your problem, I think that it is more probable that as your older engine warms up the clearances in the oil pump and the engine bearings increase and in conjunction with the warmer oil, that's where you are losing oil pressure. And you are seeing it at the lower RPMs because the oil pump isn't turning as fast and moving oil like it is when you are running the engine faster.

That's my guess, anyway.
It's really not an uncommon scenario.

As far as putting in a mechanical/direct oil pressure gauge, I am sure that is doable. I bet you could shop around almost anywhere (like Amazon) & find one for your application.

Someone on this site once recommended a 'T' so BOTH could be installed at the same time. Otherwise, if you pull the OEM one, the PCM will always be thinking you have NO oil pressure & it will light up the check gauges light.

But on edit: before go changing the cluster, there is a self diagostic check you can easily do on the cluster. If you need me to, I can type it out for you if you want to try that.
 

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. . . here you are. I am copying & pasting this from an answer I gave someone related to his voltmeter, but this will check all of the gauges on your cluster. This is from the '03 FSM, but I believe that it will be applicable to your '02. (I have paraphrased & condesnsed from the actual FSM text as I am a poor & slow typist.


Okay, with the rules of paraphrasing & condensing that I listed above, the actuator test puts the cluster into a self diagnostic mode.
Successful completion of test confirms that the cluster works, but there still may be a problem with the PCI bus, the PCM, the CTM (Central Timer Module) the transmission control module (TCM), transfer case control module ((TCCM) , Airbag control module (ACM), the CAB (basically the ABS module), or inputs to one of these modules. The FSM tells you to use a DRBIII scan tool to diagnose these components.

Okay, first off there is a large warning paragraph in bolds warning you of the dangers of screwing with your steering wheel etc related to setting your airbags off. For now, I believe this is not applicable. If it looks like it is, I will come back to it.

1)put ignition switch to OFF
2)depress odometer/trip meter switch button
3)while holding trip meter switch button depressed, turn key to ON but do not start engine
4)keep trip meter switch button depressed for about 10 seconds until CHEC appears on odometer display then release.
5)a series of 3 digit numeric failure messages may appear in the odometer depending upon failure mode.

(If you get one of these, post it & I will get back to you & let you know what it is.)

6)instrument cluster will begin the vacuum fluorescent display (VFD) walking segment test. W#e can skip that for now except to say that it involves the "segments" illuminating in a sequence. As I typed, we can come back to that if need be.
7)cluster will perform a bulb check. I think we can skip that for now, also, but if need be we can get back to it.
8)gauge actuator test: cluster circuitry positions each gauge needle a 3 different calibration points then returns them to their relaxed positions. If an individual gauge does not respond properly or does not respond at all, the cluster should be removed.

(This is where the warnings in bold that I previously alluded to come into play.)

However, check that the spring clip terminal pin receptacles on the cluster electronic circuit board before considering cluster replacement
. If gauge terminal connections are okay, replace the faulty instrument cluster.
9)actuator test now complete. Cluster will automatically exit self diagnostic mode & return to normal operation, at the completion of test, if the ign switch is turned to OFF during test, or if a vehicle speed message indicating that vehicle is moving is received from the PCM on the PCI data bus during the test.
10)repeat as needed.

If there is anything that I typed that isn't making sense, let me know--maybe it is where I over condensed or paraphrased too much. I can get back to that point & expand & expound, directly quoting the FSM.
 

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Discussion Starter · #4 ·
Yea I tested cluster it all worked. If it’s bearing clearance what can be done instead of tearing motor down? Oil pressure is fine with mechanical though. Yes I know if unplug sensor light will stay on. I was hoping someone would have know what resistor to put in to trick the gauge
 

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So you are saying that you have put a mechanical gauge on & you get good oil press?
That would tend to make my theory about excessive clearances null & void.
However, if it is excessive clearances, not much you can do except live with it or tear the engine down.

As far as a resistor to trick the gauge/PCM, that's over my paygrade.
But if you have done the diagnostic check & it passed, I believe that means that the cluster is not the problem.
 

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Discussion Starter · #6 ·
So you are saying that you have put a mechanical gauge on & you get good oil press?
That would tend to make my theory about excessive clearances null & void.
However, if it is excessive clearances, not much you can do except live with it or tear the engine down.

As far as a resistor to trick the gauge/PCM, that's over my paygrade.
But if you have done the diagnostic check & it passed, I believe that means that the cluster is not the problem.
Yea mine too lol
 

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Discussion Starter · #7 ·
Do you think it is cause im using aftermarket oil pressure sensor? I know some truck like ford diesel some sensors don’t work at all ?? Part number for oem sensor if you have that by a chance
 

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Do you think it is cause im using aftermarket oil pressure sensor? I know some truck like ford diesel some sensors don’t work at all ?? Part number for oem sensor if you have that by a chance
I cannot honestly answer that as I cannot recall ever having one fail on me; therefore I've never replaced one for that reason. (I did change the one on my high mileage GMC just because I had the top of the engine apart, and that made a bitch job a lot easier, but it wasn't because of failure, it was only for preventive maintenance.)

But just so I understand, you are saying that you put a mechanical gauge on and you get good pressure?
So along with the check gauges light, I guess your OEM gauge is also showing way low pressure at idle?

As far as tricking the system to turn the light off, I am not really sure how that would work. I can get in the FSM & read back up on it, but if I remember, the sensor sends the signal/message to the PCM and everything that happens on the cluster is a result of what is coming from the PCM. (Assuming, I guess, that the cluster is operational, & I would think that the diagnostic check you just did means that it is.)

So I guess if I backtrack on this a bit, and you actually are making good oil pressure at idle (as confirmed by mechanical gauge) but the cluster tells you that you aren't, that might mean it is the PCM that is at fault?

I don't know. My standards aren't that high, so I'd probably put in the mechanical gauge, and as long as it told me that my pressure was withing parameters, I'd live with the light.
 

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Discussion Starter · #9 ·
Sounds like what Imma do.. the pcm reads off what gauge is say by volts( as far as I understand). Yes getting good oil pressure at idle with mechanical gauge. Imma try new oem pressure sensor and see what that does. If not put mech gauge on and find a way to trick the gauge
 
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