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2005 2500hd crew LS
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Discussion Starter · #1 ·
I've been slowly getting my newly purchased LLY up to par. The fuel guage has never worked correctly and the previous owner said it had been out for a while.
When I bought it the odometer read error yet the gear indicator worked.
For 2 weeks of driving there wasn't anything weird happening.
Yesterday I removed the radiator and cleaned it along with replacing the alternator. During service i disconnected the batteries as not to short somthing out. Upon finishing I noticed that now my odometer read zero, its saying the oil pressure is low and almost zero at idle, and the truck runs fine below 2000rpm but wont rev past that. There are no codes present.
I'm guessing it's in limp mode or somthing. I need some help fellas
 

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Check all your battery connections and test your battery voltage, including load test if possible. Low voltage can cause all kinds of weird stuff to happen.
 

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2005 2500hd crew LS
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Discussion Starter · #3 ·
Will do. For that matter I can put it on a charger tomorrow when I get to my shop. Which battery do I charge from? Or both?

I'm a pretty good auto mec vhf anchor and work at a polaris side by side OFFROAD shop but I'm new to the diesel scene
 

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2005 2500hd crew LS
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Discussion Starter · #4 ·
I just went out and started it and now my cluster is reading g error again like it did before the other weird cluster issues and b4 limp mode. How to you get it out of limp mode?
 

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I’ll have to let someone else chime in on that. A battery reset would usually do it I thought, even if it comes right back.

Also closely inspect the long wire loom that connects to everything under the hood. There are a few spots where it’s known to get stretched/pinched and wires can get rubbed or broken and act up.

I’ve found most of the everyday stuff that goes wrong with these trucks is not diesel specific. I just bought mine last year so I’m a relative newbie too, but have read a ton here and the other popular Duramax forum.
 

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Will do. For that matter I can put it on a charger tomorrow when I get to my shop. Which battery do I charge from? Or both?
You want to Load Test and charge both batteries. Load Testing is different from a voltage test.
 

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2005 2500hd crew LS
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Discussion Starter · #7 ·
Do I need to disconnect each battery b4 I have orielys load test them. It will draw from the other if they test while installed.. right?
 

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Do I need to disconnect each battery b4 I have orielys load test them. It will draw from the other if they test while installed.. right?
Yes, remove both batteries and take them down to OReillys. Ask the staff to individually load test them
 

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I've been slowly getting my newly purchased LLY up to par. The fuel guage has never worked correctly and the previous owner said it had been out for a while.
When I bought it the odometer read error yet the gear indicator worked.
For 2 weeks of driving there wasn't anything weird happening.
Yesterday I removed the radiator and cleaned it along with replacing the alternator. During service i disconnected the batteries as not to short somthing out. Upon finishing I noticed that now my odometer read zero, its saying the oil pressure is low and almost zero at idle, and the truck runs fine below 2000rpm but wont rev past that. There are no codes present.
I'm guessing it's in limp mode or somthing. I need some help fellas
Those early trucks are notorious for having the instrument gauges to quit working. First, our oil pressure gauge went out, then the gas gauge, then it totally went blank. I found out that GM was replacing them on some trucks, but ours was 17 yrs old and they wouldn't do it, even though they knew they were bad. I found an entire instrument gauge panel on E-Bay for less than $300 and had my local mechanic replace it. Not difficult to do.
 

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I've been slowly getting my newly purchased LLY up to par. The fuel guage has never worked correctly and the previous owner said it had been out for a while.
When I bought it the odometer read error yet the gear indicator worked.
For 2 weeks of driving there wasn't anything weird happening.
Yesterday I removed the radiator and cleaned it along with replacing the alternator. During service i disconnected the batteries as not to short somthing out. Upon finishing I noticed that now my odometer read zero, its saying the oil pressure is low and almost zero at idle, and the truck runs fine below 2000rpm but wont rev past that. There are no codes present.
I'm guessing it's in limp mode or somthing. I need some help fellas
It's keeping the rpm limited because it sences low pressure. I would put a gauge on it to make sure you have pressure b4 going any further. The instrument cluters are a problem in that year truck as well as other years. They rebuild them for about $120 led lights and new motors that run the gauges. Fuel gauge prolly the tank unit, but I would start with the instrument cluster as the fuel gauge itself may have a burnt motor.
 

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2005 2500hd crew LS
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Discussion Starter · #13 ·
Sent the cluster out to dr speedometer today. Found him online and it seems Silverado are all he works on. Guess we keep him busy. Ill let yallbknow what the outcome is. Thanks for the help
 
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