2004 K2500HD 6.0 oil pressure gauge problems

[OR VietVet]

I have been seeing the odd oil pressure gauge reading for a couple days. Was completely normal. I think the problem is a stepper motor. If it is, I will just get a new cluster from Digital dash solutions. I have a Foxwell NT710 scanner that will graph oil pressure readings. The graph is from 0 to 5. When I start the engine, it idles around .5 and you can see what happens when I rev it on the graph and at the gauge. The lowest the gauge reads is around 40 psi and then does climb while driving and if accel hard enough, it goes past 80 psi. When engine is cold and KOEO, the reading is around 40 psi.

Here you go:

 

[OR VietVet]

@89Suburban, it is gonna be a stepper motor and therefore I am going to customize the dash cluster at Digital Dash Solutions.

I sent the pic and the video to them. They were asking questions and a pic/video says it all. No engine noises though.

 

[Fless]

You could pull the custom cluster from your Tahoe and install it here to see how it acts.

Have you thought about disconnecting the connector on the sender to see what the gauge does then?

Back in 2020 I compared the Oil Pressure Sender Voltage with my gauge readings:

YMMV

 

[OR VietVet]

You could pull the custom cluster from your Tahoe and install it here to see how it acts.

Have you thought about disconnecting the connector on the sender to see what the gauge does then?

Back in 2020 I compared the Oil Pressure Sender Voltage with my gauge readings:

View attachment 445911

YMMV

Good idea on the cluster swap. They are so easy to do.

Thanks for the voltage/gauge comparison readings.

No, I had not thought of disconnecting the sender switch. I have a new GM sender and if I gain access to disconnect, I am going to change the sender.

Remember on my Tahoe build thread how I got carried away.

It looks like I am going to keep the truck and end up putting my Tahoe up for sale here at the forum.

UNLESS, my girl takes it over and we sell her 75k miles TrailBlazer.

I really don't think she will part with the 1990 K2500. She has had it close to 14 years and loves that truck.

So, everything is up in the air for now.

 

[Fless]

I'd be interested if you compare either cluster readings to the voltage readings to see how mine and yours differ.

 

[OR VietVet]

I'd be interested if you compare either cluster readings to the voltage readings to see how mine and yours differ.

If I do that, I will compare for you, but it does sound like a good idea, especially since it is so easy to do.

 

[Fless]

One other thing that comes to mind (think "scatterbrained" and I won't be offended) is that if the sender is compromised and leaking oil into the sender connector, that could be skewing the readings.

 

[OR VietVet]

Tomorrow is a "check it out day". Looking for leaks, I see none on ground, and hope to swap the clusters.

 

[OR VietVet]

@Fless, I think it is interesting that at 35 psi the voltage reads 1.69. 5 more, 40 psi and the voltage reads .17 more at 1.86 volts. Then at 45 psi, the voltage reads .20 more at 2.06 volts. Then 5 more psi again at 50 and the voltage jumps to 2.29 for a gain of .23 volts.

But when the psi jumps 10 psi more from 50 psi to 60 psi and the voltage only changes .12 volts to a total of 2.41 volts. Jumps 10 psi and the voltage difference does not climb as much as I thought it would. Do you know what the reason is for that?

 

[Fless]

Well, I'm not sure how GM programs that conversion in the PCM, but it looks to me like it is some kind of logarithmic calculation, so not linear.

 

[OR VietVet]

Ok, I did the dash cluster swap from my 2005 Tahoe Z71, with a transmission temp gauge, in to the dash of the 2004 K2500HD, with the transmission temp gauge. I hope the videos come up right. The first video is supposed to be the Tahoe cluster showing it is working the way it is supposed to work, while plugged in to the 2004 and then the bad cluster back in the 2004.

Sorry, when I said that the OE cluster went to "10" with Key Off I meant 20 psi, but either way, It is not acting like the good cluster out of the 2005 Tahoe.

Also, sorry, I did not hook up my Foxwell NT710 to graph the oil pressure voltages. I was doing all this with the sky pouring down rain and I was ready to be done. But, the videos back up my stepper motor theory.

Helpful hint: When removing the cluster and removing the connector at the back, as you squeeze both the grey and the blue release tabs, push in while doing so and then you will feel the tabs "relax" and then pull the connector loose. Don't fight it.

 

[Fless]

The first video is good, but the second one is marked "private."

Looks like a stepper motor or cluster issue. Good oil pressure.

EDIT: one of these days I'll find a worthwhile cluster to grab at a UPull. So far they've all been pretty beat up. Wouldn't mind having one to do some light bench testing.

 

[OR VietVet]

For some stupid reason the second video will not let me save as public. I did change the video to be viewed public at 11 a.m. today. So, hopefully in 10-12 minutes you can see it. When I open the video, I can see it no problem. Sorry.

 

[OR VietVet]

@Fless, are you able to access the 2nd video now?

 

[Fless]

@Fless, are you able to access the 2nd video now?

Yes, not the second one in post #11 but both in #13.

 

[OR VietVet]

@Fless, I just did the voltage/pressure testing on my own Tahoe. I will do the truck one of these days.

At IDLE--------Pressure 35 and voltage was at 1.70
PSI----- VOLTAGE
40------ 1.78
45------ 2.00
50------ 2.14
55------ 2.25
60------ 2.41

All these readings are with me trying to be as steady as possible with the rpm's.

 

[OR VietVet]

@Fless, I forgot to tell you. No oil leakage at connector or sender.

 

[OR VietVet]

Went ahead and ordered a new dash cluster from Digital dash Solutions. Hope to have here by end of week and will send the old one back so I can take advantage of their Lifetime Warranty. They pay for shipping to me and return shipping of the old cluster. I chose to just stick with the stock dash set up for $250. I was thinking of silver needles instead of the OE orange needles but that was $25 more. The stock look and lighting is fine with me. Thankfully the R&R of the clusters will be a less than 30 minute process. In the anticipation of a possible oil pressure sender/switch, I had bought a new Genuine GM switch at the local wholesale warehouse. My shop owner friend allows me to use his shop account as long as I pay C.O.D.

Thankfully, most of the Genuine GM parts I have stashed back, for my 2005 Tahoe Z71, also fit this 2004 K2500HD.

 

[OR VietVet]

Received the new dash cluster and installed asap. The fluctuating oil pressure problem is "no more". All Fixed.

 

[Fless]

Received the new dash cluster and installed asap. The fluctuating oil pressure problem is "no more". All Fixed.

I've never heard a bad word about DDS, and he has a good selection.