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2004.5 - 2005 LLY FAQs
Here is a compiled listing of the most popular LLY topics discussed here at DieselPlace.com. This is to help you speedily find your answers, without having to wait for a reply to your question. We love to answer questions and enjoy gathering around the computer to help others out. We’ve all been there. This forum is a living library of information.
Click on the solid underlined word of any topic of interest and it will hyperlink you to the area in the forum where the information was first posted.
If you don’t find a topic listed, feel free to do a search. You may have to do an individual word or a phrase search, as with any search engine you may need to be creative in describing what you are looking for, don't give up if the first search you type comes back with nothing found. There is an entire forum search, and you can search within a forum subgroup, author, subject, or date. It may be worth your while to read all FAQ topics first so you can inject common phrases to work with on your searches.
Building the FAQ library - If you see a topic that you want to add or think should be added, please contact a staff member.
Latest updates posted - April 2020.
Other Topics Of Interest
A
Acronyms found on Diesel Place
B
Block Heater
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C
Common LLY Issues
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D
Diagnostic Trouble Code (DTC)
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E
EGR
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F
FPR
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G
Glow Plug System
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H
Harness Rub Repair
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I
Injectors
Intermediate Steering Shaft
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J
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K
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L
Lift Pump
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M
MIL
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N
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O
Oil Pressure
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Here is a compiled listing of the most popular LLY topics discussed here at DieselPlace.com. This is to help you speedily find your answers, without having to wait for a reply to your question. We love to answer questions and enjoy gathering around the computer to help others out. We’ve all been there. This forum is a living library of information.
Click on the solid underlined word of any topic of interest and it will hyperlink you to the area in the forum where the information was first posted.
If you don’t find a topic listed, feel free to do a search. You may have to do an individual word or a phrase search, as with any search engine you may need to be creative in describing what you are looking for, don't give up if the first search you type comes back with nothing found. There is an entire forum search, and you can search within a forum subgroup, author, subject, or date. It may be worth your while to read all FAQ topics first so you can inject common phrases to work with on your searches.
Building the FAQ library - If you see a topic that you want to add or think should be added, please contact a staff member.
Latest updates posted - April 2020.
Other Topics Of Interest
- The LLY Photo Thread - Click Here
- What Did You Do To Your LLY Today? - Click Here
- DP Member Map - Click Here
- Manuals - Click Here
- Duramax Engine Info - Click Here
- LLY Part Numbers - Click Here
A
Acronyms found on Diesel Place
- Find out meanings to common acronyms - Here
- Factory vs aftermarket Comparison - Here
- LBZ Mouthpiece Information - Here
- 105 amp alternator belt size is 6 ribs at 118.75 inches.
- 145 amp alternator belt size is 6 ribs at 119.5 inches.
- Activating at slow speeds - Here
B
Block Heater
- Plug Location - Here
- The bottle test is a common test to run to determine if the Fuel Pressure Regulator Value (FPRV) is operating correctly.
- How To Guide - Here
- Where to tap for a boost gauge - Here
- How To Guide - Here
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C
Common LLY Issues
- Link 1 - Here
- Link 2 - Here
- Overheating Issues - Here
- Cooling Stack Cleaning - Here
- DIY Secondary Cooling System - Here
- Grease Fitting Locations - Here
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D
Diagnostic Trouble Code (DTC)
- Look Up Tool - Here
- Installation Guide - Here
- Lower power lights that are always on if the truck is in gear. They turn off when the main headlights come on at dusk.
- A multi-position switch, usually 2 or 5 positions, for changing between different EFI Live tunes.
- How To Guide - Here
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E
EGR
- Blocking the EGR means you put a plate in between the exhaust riser and the EGR cooler to block the flow of exhaust gas into the intake. The EGR motor stays plugged in and on FE9 trucks you shouldn't see any hard codes (I.E. won't turn on CEL but you may still have codes stored in the ECM). Others may need to wire in a "Fingerstick" which fools the ECM into thinking all is still working with the EGR. (Credit: mtl_dmax)
- Deleting the EGR mean that the EGR cooler and EGR motor are removed completely from the truck. You will need to install an EGR delete intake tube in its place to connect the hot side boost tube to the elbow on the intake bridge. Due to this you'll need to cap off the exhaust riser on your up pipe or run an LB7 passenger side up pipe (which has no riser). You'll also need to reroute the coolant from the coolant tube at water pump to the heater core with a 2ft section of 5/8" hose. Lastly you'll also need something to turn off the codes for removing the EGR motor. (Credit: mtl_dmax)
- How to and FAQ on EGR - Here
- The factory exhaust size is 3.5 inches, common after market exhausts are both 4 inches and 5 inches.
- The post popular after market 4 inch exhaust system - Here
- EFI Live tuning software tips and tricks - Here
- Elevated idle is different then high idle. Elevated idle is a feature to aid in warming up the engine in cold temperatures.
- Information about elevated idle and how to enable it - Here
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F
FPR
- Stands for Fuel Pressure Regulator, it is what maintains the rail pressure for the injectors. Surging and RPM fluctuations at idle are common symptoms of a filing FPR.
- Replacement Guide - Here
- Stand for Fuel Injector Control Module. This rarely failing on the LLY Duramax - always do the Ice Pick procedure before replacing the FICM.
- Loosing fuel prime is often associated with an air leak at the fuel filter housing. A filter rebuild can often cure this issue. How to rebuild the filter head - Here
- Guide for changing the fuel filter - Here
- Lift pumps are often used on modified trucks to provide positive fuel pressure to the CP3 injection pump. This is because the Duramax does not have an in tank fuel pump. See lift pump for more information.
- Oil - Baldwin B1441 | ACDelco PF2232 | WIX 57202 | NAPA 7202 | Amsoil EA 052
- Fuel - Baldwin BF9882 | ACDelco TP 3012 | Racor PFF50216 | WIX 33960
- Transmission - Allison 29539579
- Guide for replacement - Here
- This is the RPO code (see RPO code) that designated trucks with Federal Emissions requirements.
- A fingerstick is a simple circuit that modifies the MAF signal on LLY engines to expected levels when the EGR is blocked or a free flowing exhaust system causes the ECM to set codes. This will prevent a Service Engine Soon (SES or MIL) light from illuminating and will prevent the ECM from displaying DTC codes related to an EGR modification or larger exhaust. (Credit: skoryaro2)
- Fingerstick install guide - Here
- Removal Information - Here
- Engine Oil - 10 Quarts
- Engine Coolant (manual transmission) - 20.7 quarts (automatic transmission) - 20.3 quarts
- Transmission fluid (Allison) - Drain via pan ~7.5 quarts | Full flush ~ 5 gallons
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G
Glow Plug System
- GPCM - Glow Plug Control Module
- Replacement Instructions - Here
- What to do when a glow plug breaks on removal - Here
- Having a gauge read incorrectly is a common issues, the offending part is the stepper motor that moves the gauge needle.
- Cluster repair guide - Here
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H
Harness Rub Repair
- TSB 09-06-04-034: This condition may be caused by the fuel injector control module (FICM) wiring harness protective conduit rubbing against the back of the alternator, the alternator bracket or the FICM harness retaining bracket and may throw several DTC's. Click Here
- A common mod people do that allows you to retain your low beam headlights and fog lights when you enable the high beam headlights.
- How to guide - Here
- The headgaskets are one of the know issues with the LLY engine. It is due to a bad gasket design from GM. This issues is further compounded when the engine is run hot.
- Common symptoms include - using coolant, hard upper radiator hose after 12 hours of rest, coolant being pushed out the overflow, and erratic engine temperature.
- Tips and Tricks - Here
- High idle is different from elevated idle (see elevated idle). All it does it raise the engine RPM using the power take-of (PTO) functionality of the truck.
- High idle install guide - Here
- Hydroboost is the system in the powers the trucks power steering and power brakes. Flushing the hydroboost system is a good idea and can improve brake pedal feel and steering feel.
- How to flush guide - Here
- Element replacement guide - Here
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I
Injectors
- How to properly check balance rates - Here
- Injector cleaning procedure - Here
- How to replace an injector - Here
- The number 2 and 7 injector harnesses are known to rub through causing the injector to stop working. The common fix is called the Ice Pick Fix, every LLY owner should know this procedure.
- Ice pick fix guide - Here
Intermediate Steering Shaft
- The Intermediate steering shaft is a known issue where it will clunk and/or cause vibration in the steering wheel. There are several fixes, but the most basic is just re-lubricating that shaft. Some also suggest replacing the bushing the shaft rides on.
- Lube Procedure - Here
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J
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K
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L
Lift Pump
- Lift pumps are often used on modified trucks to provide positive fuel pressure to the CP3 injection pump. This is because the Duramax does not have an in tank fuel pump.
- Kennedy Diesel lift pump install guide - Here
- A discussion between lift pumps and FPRV shim - Here
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M
MIL
- Stands for Malfunction Indicator Lamp - also known as your check engine light. MIL is synonymous with SES.
- A common phrase used to describe the noise the truck makes for the first few miles while the fan clutch is still engaged. After a few miles when the fan clutch disengages the fan noise will go away. There isn't anything you can do to prevent this and it is not bad for the truck.
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N
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O
Oil Pressure
- If the gauge says 0 oil pressure but your not receiving a notification in the dash board you most likely have a bad stepper motor. See stepper motor.
- The LLY engine is know to have a very low warm idle oil pressure. Do not be alarmed with 20-30 psi.
- The LLY Duramax engine is known to have overheating issues when towing heavy. There are many different thoughts as to how to fix it, but the most successful way is adding a secondary radiator for additional cooling capacity.
- LOTS of information - Here
- Secondary cooling system DIY - Here
- A function of the Allison transmission that disables 5th gear. This can be enabled by pushing and holding the button the the gear shiftier for approximately 2 seconds.
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