Fuel gage intermittent inop

Jeff Owner/Technician Idaho Posted   Latest  
Resolved
Driveability
Electrical
2005 Chevrolet C4500 Kodiak C4E042 6.6L (2 LLY) 5-spd (1000LCT) — 1GBE4E1255F512997
Fuel Gauge Inop

Intemittently the fuel gauge works. I am using a snapon triton d10 scanner to observe data. The fuel level displayed in the PCM shows 73% currently, if I look oin the IPC, the level observed is “0”. We do GM clusters regularly for failed diplays and tach/speedo issues. This truck has the dual tank arrangement that combines the fuel level of both tanks to give a single overall fuel level, however My scanner will only show pcm and ipc data since I have to access it a a c3500 because snapoff does not include the c4500 info.

Any help figuring this out would be great

Thanks

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Glenn Owner/Technician
Texas
Glenn
 

Hello Jeff, Sounds like a possible wire issue. Inspect the frame harness and look for any signs of impact from a blown tire in the past or road debris impact. The other possibility is one of the tank senders is having an issue with an intermittent open or connection problem. The next thing to try is to pull the gauge unit and reseat the connectors with the key off.

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Hal Owner/Technician
Texas
Hal
 

Check for codes. If the transfer pump fails, the fuel gauge quits working. We have also seen where the customer has replaced the level sensor(s) with aftermarket. OE Level sensors must be used on these vehicles

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Jeff Owner/Technician
Idaho
Jeff
 

one question I have about a possible wire or level sensor problem, is that if one of the level sensors id defective, the control module returns an empty signal. If that is the case, then why would the PCM show 73%(base on customer info is probably a realistic actual current fill amount).

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Glenn Owner/Technician
Texas
Glenn
 

Hi Jeff, You make a good point. Could it have a redundant system with a mechanical sender and a linear sensor? Is the fuel module averaging both tanks together? The OP said this is a truck, So I am speculating this is not an RV conversion chassis.

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Jeff Owner/Technician
Idaho
Jeff
 

I remember from my days working at a GM dealership that they used a module that looked at the levels of both tanks, transferred fuel from the rear tank to the front tank as fuel was used, and that module combine the 2 levels to a total fuel level and send that to the PCM (I think), and the PCM shared the info. Was a long time ago though, 2000ish. So I think the IP is the issue, just don't want…

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Glenn Owner/Technician
Texas
Glenn
 

Hi Jeff, That is why I suggested earlier to pull the gauge pack and reseat the connectors. I have even applied a little die electric compound to the connectors and reattached many times and had them reliably working again. Over time, vibration and mileage creates conditions for harness pins to scrub and wear and that will create intermittent contact issues. I agree about not throwing parts at…

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Jeff Owner/Technician
Idaho
Jeff
 

I did this about 2 weeks ago, the connector pins are not spread and the connector plugs in snugly. We only have access to the vehicle 1 day per week for about 4 hours, its used to shuttle river rafting equipment from the takeout back to the put in and is in town for one day waiting for the shuttle people move it around the other side of the mountains. It does see a lot of washboard, so…

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Marlin Technician
Oregon
Marlin
 

You didn't on this vehicle.

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Jesse Owner/Technician
Georgia
Jesse
 

The stepper motors in the IP will fail and cause that concern.. I would check IP for loose connections or cracked solder joints. The motors are cheap to purchase and easy to desolder and resolder on the board. Hope you find it quick..

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Jeff Owner/Technician
Idaho
Jeff Resolution
 

My help in diagnosing this came today in the form of a new Autel Maxsys Ultra. It has the gm medium duty ability. I was able to read the codes correctly, and diagnose the faulty secondary tank level sensor. Thanks to all those that responded with ideas to help me.

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Marlin Technician
Oregon
Marlin
 

A Tech2 will also read the PIDs. That SO still doesn't is pathetic.

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Agree