04 Suburban Cluster Issue

[TylerHagerdorn]

I'd recommend cleaning the grounds that are on the body mount, just under the driver's door hinges (right behind the left front tire). There will be two or three wires on two bolts, and one is the TBCM ground.

I'd also pull the two PCM connectors and check for water intrusion and pin fitment. The gaskets can leak and water can sit in the lower part of the connector.

It'll be interesting to see what you find to be the cause.

Well I'm still figuring it out. I got a known good PCM from a truck with matching RPO codes and a flex truck because it does matter. We put one from a gas truck(VIN T) and the fuel level wires must be backwards because full was dead empty and it moved like it should.

But here's the issue right now. We installed a brand new Delphi pump over the weekend and then filed it up...that's when we saw the gauge reading backwards...so more research showed that the VIN Z Flex trucks use a different PCM and fuel system, pump connectors are different so that would make sense.

Put my original PCM back in and it would only go to half tank, when there was 3/4 in it. Picked up the correct junkyard one today and installed and did the security relearn, and it's still not going past half...so I don't really know what else it could be. I have both new clusters so I changed them and still the same thing. So not a cluster issue and doesn't seem to be a PCM issue. I saw the truck at the junkyard and it read between. 3/4 and full which was the correct fuel level that was still in it. So obviously it works

What else do I check now? Do I go top it off and see if it moves? I know there's resistance values ohm wise for the different levels of the fuel level sender. I haven't tested those yet. We didn't do any wiring repair when swapping the pump, wiring was good and not corroded and fully intact. It starts perfect everytime. I don't know what else it could be.

If anyone and anything else for me to try please tell me. We've put a new Delphi pump in, known good PCM, and a brand new cluster.

 

[Fless]

A fairly decent scanner will show the fuel level % PID value to see what the PCM is reporting to the cluster. Might be good to compare that value with what you see on the cluster, perhaps even as the level changes.

How's the pin cleanliness and fitment in the PCM connectors? You may have already done this but a very careful inspection of the connector pins and use of DeOxit or similar might be something to try.

 

[TylerHagerdorn]

A fairly decent scanner will show the fuel level % PID value to see what the PCM is reporting to the cluster. Might be good to compare that value with what you see on the cluster, perhaps even as the level changes.

How's the pin cleanliness and fitment in the PCM connectors? You may have already done this but a very careful inspection of the connector pins and use of DeOxit or similar might be something to try.

Connectors are clean now. I spliced in some clean connectors because the original ones had some sort of oil substance in them. Looked like motor oil. I cleaned them but it kept coming back so I spliced in clean ones. There's no pin fitment issue.

I don't own a fancy scan tool that shows fuel level or any of that. I'm going to buy a dongle with the GM tech 2 and GDS software on it for my laptop. But that's beside the point right now.

When we installed the first used PCM(had the same part number so I didn't think anything of it) and filled it up after putting the new pump in, it read dead empty. And we drove about 160 miles and it was moving like it should, just backwards. As I found out the GAS trucks use a different fuel pump and connector so the level input to the PCM is reversed. And I now have a good working PCM in there now from a flex truck with identical rpo codes. And that truck read the correct fuel level, which was around 3/4 tank. So I don't believe it's a PCM issue. Has to be something else.

The fuel level goes from the tank up to connector C152, then from there to the PCM. And then there's a fuel level wire that goes to the cluster. I don't know what else to check. Cluster connector is good, PCM connectors are good. Where else do I go? Like I said there's resistance ohm values from full to empty. I haven't tested those yet. I'm not dropping the tank again lol. I have severe health issues and deal with bad chronic pain. It was a nightmare doing the pump.

 

[GMfan72]

Hey Y'all.

I had a faulty cluster in my 04 Burb, the fuel gauge would randomly drop to dashes on the range screen. And then when you hit the gas pedal and gave it decent throttle, at an idle, the gauge would come back to life. I chalked it up to a bad cluster since these are so notorious for going bad.

However I purchased a fully rebuilt one from ISS, which I've heard nothing but good things about. I put it in Wednesday, and it seemed to be functioning properly minus the DIC screen being very dim. I contacted them and they've sent me another one I'll receive Tuesday.

The issue started again today with the new cluster going to dashes with the low fuel light on the dash, and jumping back up when giving it throttle at an idle. Smacking the dash does nothing to make it respond...only hitting the throttle does. When driving it seems perfectly fine.

So my question now is, why is the fuel gauge going to dashes on the range and going back up when throttle is applied? This is my 4th GMT800 and the first one I've had these cluster issues with. Could the plug for the cluster have loose pins not giving it solid contact? I've been on alldata and got all the wiring diagrams for the cluster and all that and traced wires, minus to the fuel pump because I can't drop the tank on th ground due to my health. But the truck starts fine every single time. No CEL.

I'm absolutely lost. This is so strange. Any help or advice would be so appreciated. Thank you

Hi - I have seen a couple other posts from you. you have described intermittent problems that change with engine running. I would change the vehicle's overall Ground Cable. I have an 2004 and was have various intermittent issues and after I changed the Ground Cable it corrected most of the problems. I am not sure what part of the country you live in but these cables tend to corrode over time.

 

[ivin74]

Connectors are clean now. I spliced in some clean connectors because the original ones had some sort of oil substance in them. Looked like motor oil. I cleaned them but it kept coming back so I spliced in clean ones. There's no pin fitment issue.

I don't own a fancy scan tool that shows fuel level or any of that. I'm going to buy a dongle with the GM tech 2 and GDS software on it for my laptop. But that's beside the point right now.

When we installed the first used PCM(had the same part number so I didn't think anything of it) and filled it up after putting the new pump in, it read dead empty. And we drove about 160 miles and it was moving like it should, just backwards. As I found out the GAS trucks use a different fuel pump and connector so the level input to the PCM is reversed. And I now have a good working PCM in there now from a flex truck with identical rpo codes. And that truck read the correct fuel level, which was around 3/4 tank. So I don't believe it's a PCM issue. Has to be something else.

The fuel level goes from the tank up to connector C152, then from there to the PCM. And then there's a fuel level wire that goes to the cluster. I don't know what else to check. Cluster connector is good, PCM connectors are good. Where else do I go? Like I said there's resistance ohm values from full to empty. I haven't tested those yet. I'm not dropping the tank again lol. I have severe health issues and deal with bad chronic pain. It was a nightmare doing the pump.

Does the DIC show how many miles are left to empty?
Reset the DIC that shows how many gallons you have used of fuel. Fill her up drive the suv to almost empty, fill her up again and compare the results. If the numbers don't match you have a faulty fuel pump that is reporting incorrect values to the pcm. Did you use a Delphi or oem fuel pump when you replaced the old pump. I have had issues with brand new aftermarket fuel pumps. I only use oem fuel pumps.

 

[TylerHagerdorn]

Does the DIC show how many miles are left to empty?
Reset the DIC that shows how many gallons you have used of fuel. Fill her up drive the suv to almost empty, fill her up again and compare the results. If the numbers don't match you have a faulty fuel pump that is reporting incorrect values to the pcm. Did you use a Delphi or oem fuel pump when you replaced the old pump. I have had issues with brand new aftermarket fuel pumps. I only use oem fuel pumps.

I've mentioned it before in this post. It's a brand new Delphi pump. I've been in the parts business and working on vehicles for over 14 years...never had a single Delphi bad out of the box. It's not the pump. There is a PCM update to fix the issue of the fuel gauge not reading fully full...so that's my next move. The gallons used isn't accurate either due to that. I filled it up, 31 gallon tank, drove 29 plus gallons and no low fuel light. Testing shows that the PCM is showing dead empty for full, so it needs updated and reflashed.

 

[Burban22]

I had a similar issue in my 03 burb where the fuel gauge would read E and low fuel on the DIC but if you would rock the burb side to side it would read fuel level normally.

I also had a code for P0463 fuel level sensor circuit high.

This is a common problem on earlier years where the fuel level sensor metal fingers wear away and give inaccurate readings.

The fix was a new fuel pump with robust fuel level sensor that’s supposed to be more resistant to ethanol content in fuel.

I’ve put 10k and 1 year on this Carter pump and hasn’t missed a beat. Fuel gauge works normally now as well!

https://a.co/d/8IrOToV

 

[GMfan72]

I have a 2004 GMC Yukon XL. I was having other electrical issues similar to what you are mentioning with the ----- in the Fuel Range in the cluster. I ended up changing out the actual Ground Cables for the vehicle. In the northern climates with snow, salt etc. the cable corrodes and sometimes it is not the connector to the frame but the actual cable corrosion. After changing the ground cable for the vehicle it corrected all the little intermittent electrical 'gremlins'.