Btw, I didn't link that red "Fuel" , it just came up like that...lol

 

Per Car Gauge Pro on my 2004 Avalanche it seems you should use the Fuel Gauge Control PID. Your gauge should be reading 81.2% of full. Looks like problem is in gauge cluster.

My vehicle reads 47% with fuel gauge just under half.

Now fill yours up and see at what point it reads 100% on the scanner. Then completely fill tank and see how much more. That should let you know if computer is seeing things correctly.

 

Okay, I'll do that in the next couple days. So, you are saying with the Car Gauge Pro, fill from the 81.2 to 100%. Then, fill the rest of the way and keep track of whether or not much more goes in...if I understand correctly.

 

Yeah, I think that would check things out a little better to make sure the computer is seeing things correctly. Should be nearing full when computer is seeing 100%. Usually a few gallons above full to completely fill a tank. Give system a little time to respond (fill with gas slow and let things stabilize every so much) as I think there is a significant delay to prevent the gauge going up and down over inclines and with starting and stopping.

If other gauges are working well, know that they share the same serial data line from the PCM - so that couldn't be an issue. Then that would only leave the stepper motor itself for the gauge. Here's a kit to replace all the stepper motors, but I think you can get them for just one gauge - or send them in for repair.

 

Sweet! I didn't have a clue how those worked...

 

I had a clue but no real understanding until we started in this thread!! That is the nice thing about trying to help people who will do what you ask - it gives me an occasion to learn as well and I guess that is why I do it. I tend to lose interest pretty fast when someone won't follow directions, as it ruins the learning process for me. I just like to learn stuff and think some of these systems are pretty amazing.

 

Well, to be honest, some of the stuff has been over my understanding. I try to do what I can get a grasp on though. I was just telling my Wife about the Friends I've made on here. I've learned a lot in the last few months from several people.
The funny thing I was telling her was how I would try to miserably explain my problem and you Guys would try to help diagnose it. I just appreciate the help!
Btw, If the software will monitor the fuel level, I probably won't tear into the dash for now. Too much other stuff going on... but very interesting info Les
Later

 

I still haven't got fuel yet but each time I cranked the truck, the fuel gauge got closer to the "fuel Control level". Then it went from 3/4 full tank to 1/4 and then 1/2 tank.
All the other gauges are fine. Quite possibly the stepper motor?
later

 

I would think so if the rest of the gauges read fine and the PCM can be verified to be reading the fuel tank correctly. Nothing else it could be other than the gauge cluster circuitry itself or the stepper motor.

Hey, guess what.... I tried to find that same fuel level PID in Torque Pro for my Avalanche and could not find anything that worked (same thing with cam sensor retard for 1998+ Blazers and Pickups - it's just not there). Advantage goes to Car Gauge Pro once more! I tell you - if you can get past the PIDS listed in Car Gauge Pro that don't work, the ones that do are often very advantageous and can be hard to find elsewhere. The only bad thing is you have to figure out if an extended PID works or not in Car Gauge Pro. Did you notice that one of the PIDs I originally listed for you to try for fuel level, gave values that were reading but obviously B.S? Just like the CMP retard PIDs (* and **). Apparently for another car, and was listed without being filtered for the specific vehicle. On the other hand, Dash Command seems to be pretty good about filtering out PIDs that won't work but I think they probably limit themselves a bit this way.

Torque Pro will highlight the PIDs that are returning data and are apparently working in green and give the current value, if you go to graph data and click on select x axis sensors or simply stop short of actually adding a PID to the gauge screen . I have always found that very useful way to know what Torque Pro will do on a specific vehicle. It's also a quick way to use Torque Pro to scan and display a PID without making a new gauge.

I just remembered that recently I did a connect/GM/Scan all faults (which seemed to be another way of checking codes) on the Avalanche using Car Gauge Pro and came up with a HVAC code B0414 and another HVAC code I don't remember right now but I looked them up at the time and had to do with blend doors. Tried to clear and they reappeared right away. Didn't pay much attention at the time because HVAC seems to work OK to me and there is no light that comes on. But I just realized that if it will scan and report codes for the HVAC module, then Car Gauge Pro just might scan for TCCM codes in the 4-button systems (which is something that a lot of people would like to do). They are all on the same data bus with the PCM. I admit I've never scanned for all faults in the Blazer and only scanned for codes from Diagnostics after connecting to Powertrain - but doing that is quite different. Maybe I can induce a code in the TCCM on the Blazer and then read it with Car Gauge Pro. I may have to try that some time!

 

Hey Les, I did forget to mention that the settings for all 5 pids you recommended read practically the same even when the gauge was back to a 1/4 tank as compared to 1/2 tank past full.
I'll probably fuel up this weekend..The Fuel Control % is still around 80 or so. Seems from memory, that should be close. I haven't been driving it much lately.
Later
Greg