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6.5 Diesel Technical Library

Discussion in '6.2 and 6.5 Technical Reference Library' started by knkreb, May 8, 2008.

  1. knkreb

    knkreb The Bus Driver is here!

    May 3, 2008
    Welcome aboard! Housed here is a growing list of information compiled by our members of technical resources for the love and care of your 6.2/6.5L GM Diesel. These engines have reputation. We are unleashing the database of how-to and why's of what you can do to keep your engine up and running it's best.

    Curious about How a Diesel Works? Here is a great explanation of that, for those who are curious about the differences between our favorites and gas engines.
    Info from Great White

    You can find the names of your parts by consulting the exploded parts diagrams found here. Pick your vehicle, year, model, and voila! Very cool!

    Now that you know what it's called, look deeper about what the members have posted about those parts:


    A1 Customs - a non-site vendor to avoid at all costs. AKA - Steaksauce.

    Acetone - Folk lore fuel additive. Don't add it to your tank. It's not compatable with fuel system components.

    AMG block here
    Info from chrisK1500

    AMG block A bunch of AMG blocks escaped the foundry with only one little defect. Info on how to recognize them and what to do to repair them is found here.
    Info from Missy Good Wench

    Air-To-Air Intercooler (ATA) - A charge air cooler using ambient air to cool the charge air (air compressed by the Turbo, heading to the intake). Charge air passes through the intercooler fins while ambient air is forced over the fins. Much the same way a radiator cools engine coolant, only the engine coolant is replaced by charge air.
    Info from RCpullerdude

    ATF (Automatic Transmission Fluid) - Belongs in your automatic transmission (Duh). It's another Folk lore fuel additive that some people keep posting will 'clean your injectors, remove deposits, and increase lubricity'. Don't add it to your tank. It doesn't do all those things (although it may have some value in gassers), and can stain the Optic Sensor (OS) in your Injection pump. Same as adding waste oil to your tank... The guys who promote this stuff don't have DS-4 Electronic Injection pumps. We do, and they like fuel without ATF or waste oil... add new 2-stroke or new 30-wt non-detergent oil for lubricity , or approved diesel fuel systems additives.

    ATT - Stands for A Team Turbo - developed and marketed here by site members, the ATT is a non-wastegated bolt-on enhanced turbo for the 6.2 and 6.5 diesel engines; it flows more air at lower temperatures than it's factory predecessors, making it an ideal towing turbo.

    Want to see one being installed?
    Look here Pictorial 1 from deejaa
    Look here Pictorial 2 from Turbine Doc

    Autoenginuity - pc-compatible user-friendly software that emulates the Tech2 for OBD2 vehicles - does TDCO LEARN and other functions of the Tech2


    Battery Connections - This post is a great show-and-tell about a simple, must-do battery post mod that will hlep keep your power flowing!
    Info from TurboTahoe

    Boost Fooler - A way of convinging the PCM that your boost levels are within range, when really, you are getting close to strecthing the head studs :) Boost foolers are built by wiring a 10k ohm linear taper potentiometer into the MAP circuit as shown here.


    CDR - Crankcase Depression Regulator - Similar to a PCV valve on a gasser. It regulates the amount of vacuum in the engine crankcase to prevent oil leaks. In parts store, it is search and listed as PCV (not CDR).

    Charge Air - Intake air after going through a turbocharger or supercharger.

    Charge Air Cooling (CAC) - Process to cool intake air temp (IAT) in a trubocharged or supercharged engine. Can be an air-to-air or water-to-air intercooler or water methanol injection.
    Info from RCpullerdude

    Cold Air Inlet mod... here
    Info from chrisK1500

    Crank Position Sensor - (CPS) - Tells your PCM what your engine geometry looks like, to control injection events. More info here.
    Info from chrisK1500

    Crankshaft pulley - Aside from being the turning force for your serpentine belt and running all your accessories, the pulley on the front of the engine works together with the harmonic balancer to stabilize the resonance of the rotating assembly. Both of them are rubber-mounted; when the rubber deteriorates, (as shown here), the pulley can disengage from the crank with devestating results (broken crankshaft). Check them often, and replace when needed... this is not a place to cheap-out.
    Info from Hydrauk

    CTS - Coolant Temperature Sensor - Here is a list of the OHM readings for the sensor at various temps.
    Info from chrisK1500


    Diagnostic Checklist - Filling this out in as much detail as possible helps to collate valuable information when your truck is sick.
    Info from JiFaire

    Diagnostic Trouble Codes - (DTC) - What do those pesky codes mean? Look here.
    Info from Schwind

    (Reading your) DTC Codes (OBD-I only) - How to use a paper clip or jumper wire to read your DTC Codes. Needs your SES light to be working.

    DS4 to DB2 Fuel Pump conversion - Loys of people want to know how to change over from the Electronic DS4 Fuel Injection pump to the older (and arguably more reliable) DB2 Manual fuel injection pump. The definitive guide on how to do this is written by our own Bobbie Martin, and is available here.
    Info from bobbiemartin

    Dyno Results - Just how much HP can you get to the wheels of a 6.5?? - Here is a list of the results that various members have submitted.

    Have you got dyno results to share? When you have a post ready, complete with a complete "state of modifications" list, and a scan ot picture of a dyno sheet, PM a Moderator to get your post included in the Dyno Results sticky.
    Info by JiFaire.


    E-Prom - Is a blue type chip found inside of the ECM on 94/95 6.5L Turbo Diesel equipped trucks.

    ECM Pinouts - Diagrams found here
    Info from DnHolland

    ECT, engine coolant temperature sensor (aka CTS - coolant temp sensor) CTS
    Info from chrisK1500

    Engine Date Codes, how to read / decode them here

    Info from Missy Good Wench

    ESO Engine shut off solenoid. Ign provides 12 volts to the ESO to allow fuel delivery into the DS4. Turning off the Ign cuts off voltage to the ESO. ESO is a 'redundant' switch.
    Info from chrisK1500


    Fan clutch mod - the thermostatic clutch fan on these trucks is famous for engaging too late to do much good... if yours isn't kicking in enough to do the job, you should replace it with a tuned severe-duty fan clutch, but here's a DIY mod that just might work for you... try this one first.
    Info from gmctd

    Fast Idle Switch Mod - On vehicles equipped with the Electronic DS-4 Injection pumps, hooking up a high-idle modfication is a simple matter. This thread talks about the process for both OBD-I and OBD-II vehicles.
    Info from mfgguru

    Filter Harness - a small black box found inline from the injestion pump harness to the optical sensor on the injection pump installed on mid 90's DS4 equipped 6.5s. Have been linked to setting codes 17 and 18 if malfunctioning.
    Info from chrisK1500

    Filter Housing Manager- a round canister (94+) that houses the fuel filter, water in fuel sensor, and fuel heater. Can be modified to a 3/8" outlet (Feed the Beast).
    Info from chrisK1500

    Flash-To-Pass - Tired of following the slow guys? Feel the need to flash somebody? Here is a DIY Pictorial on how to add this Modification to your truck!

    This article is by Burning Oil

    Fuel Strainer - the little strainer found in the Fuel Filter Manager... many people lose this little guy because it tends to stick to the filter when you change it. If it clogs up, Houston, we have a problem.
    This article is by Clipper.

    Fuel Supply - "Feed the Beast" modification. This helps to increase fuel supply for peak demand.
    This article is by Acesneights1.

    FSD (Fuel Solenoid Driver) - See PMD.


    Gear Vendors install - Have you ever wondered about adding a GearVendors under/overdrive unit to your truck? Here is how to do it, in pictures!
    This pictorial DIY is by deejaa

    GEP Engine Date codes - how do you tell what is what? Look here.
    This article is by Missy Good Wench

    Glow Plug - Heating element that warms up the air in the precombustion chamber to aid cold starting

    Glow Plug Override - a way of jumping the OEM GP relay to get extended glow time...

    Here is a quick 'how-to' on installing a manual glow plug override.
    Info from chrisK1500

    Because Variety and different viewpoints are always handy, Here is another version of installing a manual glow plug override.
    Info from Hydrauk

    Glow Plug - ECT mod for longer running; use with Bosch Duraterms, AC60g, or other self-regulating plug only. Look here.
    Info from chrisK1500

    GMTD Scantech - pc-compatible user-friendly software that emulates Tech1 capability for 94 and 95 (OBD I) trucks - does TIMESET and TDCO LEARN and other functions of the Tech1.

    Grounds - This thread documents the need for these trucks to have clean, stable grounds at all times... even the Fuse Panels need to be clean!! If you have unexplained codes or gremlins, read this!
    Info from TurboTahoe

    Grounds - Here is another thread about body, engine, and frame grounds, complete with pics.
    Info from ak diesel driver


    Heater problems... what to do when your blower quits. Look here.
    Info from Teroma25

    High Idle Mod... see Fast-Idle Mod.

    HVAC (Dash) Service ... How to rotate/remove enough of your dash to see/get at/replace the infamous HVAC Blower door assembly! Up until now, you needed to pay GM to do this one... but where there's a will, there's a way, and you can follow this pictorial guide to fix yours!
    Show-and-Tell is found right here.
    Info from Konstan


    Ignition Key Cylinder (Replacement) ... see Key Switch.

    Injector Replacement - here
    Info from chrisK1500

    Injection Pump Rebuild (DS4) - Rebuild yours, DIY Step-by-step with pictures... See how to do it all here

    Info from bison

    Intake Air Temp (IAT) - The temp of the intake air going into the engine. Significantly higher in turbocharged and supercharged engines due to the compressed air being warmer.
    Info from RCpullerdude

    Intercooler install - here
    info from Kane on his ATA install



    Key Switch - Sometimes, the key switch just breaks. Or you may need to get inside your steering wheel to repair or replace something. This pictorial write-up will show you how to do that.
    Info by deejaa


    Lift pump - Common failing part located on the frame rail under the driver's seat. How does it work? here Check it's operation to eliminate fuel supply issues. Some failures of the lift pump may even cause engine codes. See also OPS.
    Info by knkreb


    Manuals - Having trouble finding a reference manual, how-to, or wiring diagram?

    --Try looking online at Seneca Library's Auto Repair Reference Centre (ARRC).

    Info by BigArt

    --Manual for the 4L80e Transmission -Manual for the 4L80e Transmission
    Info by Great White

    --Military Engine repair Manual - for the 6.2 and 6.5

    Info by Just a Number

    Modifications - (sometimes called Mods) here is a list of things to consider if you're looking to add to your truck's longevity, reliability, or performance; all of them are good, many are cheap (or free), and you can find more information on each by searching through the technical reference library.
    info by Pruittx2



    OBD-I - Computer generation prior to 1996 model year. Computer codes can be checked with a simple paper clip... See DTC for more info
    Info by JiFaire.

    OBD-II Computer generation 1996 and beyond. Code retrieval requires a code reader. See DTC for more info

    Oil Cooler Lines - frequently leak... here's one way to fix them (with pics) Check out this thread
    Info by NVW.

    Oil Cooler Lines - Complete DIY replacement (with pictures!) with new cooler and lines from Greg at Lubespecialist. Check it out here.
    Info by Rodd.

    Oil Filter Bypass Kit - Relocate your Oil Filter to a better place!! Complete DIY replacement (with pictures!). Check it out here
    Info by Rodd.

    Online Reference Manuals - Look under Manuals, above.

    OPS - Oil pressure switch - OBD-I systems use the OPS to engage the lift pump. OBD-II systems use both the lift pump and cam signal to engage lift pump. Need to change your OPS? You'll need this tool: Lisle#13250 oil pressure switch socket..
    Info by Sunshine

    OPS Install - Changing your Oil pressure switch involves getting a little bit intimate with the top of your engine. It's a good idea to put in a relay (to ease the high-amp load on the OPS) while you're in there. This install, complete with pictures, gives you an idea what to expect!
    Info by Schwind

    Optic Sensor - Supplies the PCM with pump speed, rotor position, cam ring position, and fuel temperature.
    Info from chrisK1500

    Optic Sensor R/R - Pictorial description of how to change out your Optic Sensor - can become necessary if the old one gets stained or becomes dysunctional. Information from Roy Halvorsen, Norway.


    PCM - Powertrain Control Module. The 'brain' of the vehicle. Can be reflashed for more economy/performance.
    Info from chrisK1500

    PMD - Pump mounted driver (aka FSD/fuel solenoid driver)- common failing part. Stock location is on the side of the injection pump. Failure results in stalling. This is not the only cause for stalling.

    PMD - Stanadyne Technical Bulletin on the 'new' grey PMD.
    Info from JMJNet

    PMD Extension Cable - DIY: Solder or Crimp? - If you're planning a DIY- extension for relocating your PMD, then you need to read this very informative post before you start.
    Info from Radio Man



    Radio Lights (Changing them) - Have the lights behind your radio buttons stopped working? Here is a pictorial look at how to change them out!
    Info from great white

    Recalls - Has there been a recall on your vehicle you should know about? Find out by querying this database.

    RPO Codes - (Regular Production Options). Codes on your build sheet and located on the RPO label in your glove compartment that describe the factory options that your truck was originally equipped with. Try this handy RPO Lookup Tool and here http://www.thetruckstop.us/forum/showthread.php?36323-RPO-Codes&p=417507#post417507
    Info from Mad Maxx


    Serpentine Belt - Multi-V-Groove belt that drives the crankshaft-powered Utilities on the front of the engine... Alternator, Power-steering, Vacuum Pump, Water Pump and Fan. Routing diagram can be found here.
    Info from 96 Oilburner

    Service bulletins - Has there been a Service Bulletin about your vehicle you should know about? Find out by querying this database.

    Starter Rebuild (gear-reduction) - Rebuild yours, DIY Step-by-step with pictures... See how to do it all here
    Info from bison


    Timing Stepper Motor - (ITS). Motor located on the passenger side of the IP that controls injection timing advance and retard.
    Info from chrisK1500

    Turbo / Wastegate System ... How does it work? See here
    Info by knkreb

    Turbo Master (TM) - Is a spring actuated wastegate that sets the boost pressure by adjusting the spring tension. This precision instrument from HeathDiesel controls the Turbo-boost pressure, eliminating the GM Vacuum Wastegate-control system. Often installed when vacuum pump fails or as an owner pulls off the vacuum pump. Can be bought from HeathDiesel for ~$100 or you can make your own version for ~$10-$20.
    Info by Green Machine

    DIY Turbo Master Step-by-step with pictures... how to build your own!
    Info by mfgguru

    DIY Turbo Master #2 Step-by-step with pictures... how to build your own!

    Info by 625fireman

    Turbo rebuild - (GM8) Rebuild yours, DIY Step-by-step with pictures... See how to do it all here!
    Info by Bison



    VIN Stands for Vehicle Information Number, and is the 17-digit serial number found on your vehicle registration (also stamped onto a plate under your windshield in front of the driver, and found on other stickers and plates around your truck)... The VIN carries information about your truck including year, place of manufacture, option codes, and is your link to more information! Common usage includes looking for the 8th digit (a letter) that describes whether your truck is an F (heavy dity), S (light duty), P (Van), etc.

    Try this handy VIN decoder!! You can also post your VIN in our Vehicle Information forums (GM, Ford and Dodge) and helpful members will pull the available stored information on your truck including warranty work done, major changes and special order options.
    Info by bobbiemartin


    Warranty - Injection pump warranty is 11 years from date of service or 120,000 miles.

    Water Mist Injection (WMI) - A form of intercooling using a fine mist of water into the intake. The water provides a degree of charge air cooling, and is sometimes mixed with methanol. The methanol also adds power as a supplemental fuel.
    Info from RCpullerdude

    Water-To-Air Intercooler (WTA) - Intercooler using liquid to first cool the charge air, then another, external cooler to cool the liquid. The intercooler itself is a simple device that charge air flows through, and the liquid circulates around the charge air, removing heat from it. The liquid then flows to a radiator-type cooler to transfer the heat to the atmosphere.
    Info from RCpullerdude



    Last edited by a moderator: Nov 16, 2013
  2. bison

    bison Well-Known Member

    For your information,I did extensive research last year about the ofshore 506 blocks on the market today,I went even so far as to import one myself,and in addition to Crisk 1500 reply about fake AMG blocks with no 506 # in the valley,[by the way these blocks have metric 10mm tread in the bellhousing mounting holes,stock is 3/8 std] there are 506 blocks avalable and used by a host of engine rebuilders today that are as far as i can tell identical to genuine AMG blocks,incl 506 and the diamond in the valley, These blocks apear to be avalable only to the guy with the right contacts as i was told by the Chinese sales manager.
  3. JiFaire

    JiFaire Lieutenant Staff Member Lead Moderator

    Feb 10, 2008
    Alberta, Canada
    To build a boost fooler, you need to obtain a 10Kohm linear-taper POT from your local electronics vendor (Radio Shack #271-1715), some wire (16 ga should do) and either a decent crimp-connector set or some rosin-core solder and shrink-wrap.

    The POT wires into the 3 wires coming off the Boost sensor, mounted on the intake manifold. (shown in picture #1)

    The circuit diagram is shown in picture #2

    Once this setup is installed, starting with the POT set to O resistance, you can 'dial-up' the resistance to 'fool' the PCM into seeing less boost than is really there.

    To illustrate, your PCM will normally throw an overboost code when your boost is over 10psi sustained... it would first try to reduce the boost, but with a TM installed, that isn't possible, so it woule then defuel in an attempt to lessen the boost and prevent engine damage.

    Having a boost fooler in your sensor circuit removes this safety feature and makes it possible to run damaging high boost without the engine being protected.

    You should therefore only use this mod with gauges and a level head :)


    Attached Files:

    Last edited: Nov 2, 2009
  4. 6.5dragracer

    6.5dragracer Chevy Man...

    Feb 16, 2009
    Pasadena TX
    what is a 10K POT??? sorry but im new at this diesel stuff
  5. It's a 10 KiloOhms potentiometer. Available in every radio shack.
  6. JiFaire

    JiFaire Lieutenant Staff Member Lead Moderator

    Feb 10, 2008
    Alberta, Canada
    Here's the IP warranty policy:

    Attached Files:

  7. JiFaire

    JiFaire Lieutenant Staff Member Lead Moderator

    Feb 10, 2008
    Alberta, Canada
    If you have an OBD-I computer. You don't need a fancy-dan code reader to check your codes, just a paper-clip.

    Under your steering column, you have an ALDL plug that looks like this:


    With the key off, take a metal paper clip (or another suitable jumper wire) and place the ends in holes A and B. Get a piece of paper and pencil handy, watch the SES light on your dash (beside the speedometer), and turn the key to the ON position. The SES light should start flashing.

    flash-(pause)-flash-flash-(long pause) ... that's a code 12. Means there is nothing wrong.

    Every code will be repeated 3 times. Write them down as they come up. For instance, you could get:


    That means you have codes 17, 18, 35, 36, and 71

    When you're done, and the codes are all written down, clear them by pushing the brake and accelerator pedals to the floor, hold them for 15 seconds, let them up, push them down again, hold, and turn the key off.

    Turning the key on again should get you only a repeating code 12 (all is well).

    Shut the key off, remove the jumper.

    NEVER put the jumper in or take it out with the key on!!

    Attached Files:

  8. ocalasales

    ocalasales New Member

    May 26, 2010
    Ocala, Florida
  9. JiFaire

    JiFaire Lieutenant Staff Member Lead Moderator

    Feb 10, 2008
    Alberta, Canada
    Thank you, Ocalasales! That link is already listed in the Reference library (above) under Manuals, but it never hurts to see a reminder!
    Last edited: Jun 3, 2010
  10. daneurism

    daneurism New Member

    Feb 13, 2011
    can u put up a beter wiring diagram for the boost fooler thanks
  11. Jorge6.5

    Jorge6.5 Well-Known Member

    Jun 15, 2009
    Upstate New York
    Does it matter where the wires go on the pot? cause it does not specify thanks
  12. delinquent-d

    delinquent-d New Member

    actually, it now looks like that link is no good unless you have credentials from a participating educational institution...does anyone else have access to manuals? specifically for a '97 gm 6.5L "fuel miser" engine? (from a P-32 step van/chip truck)?
  13. denny65

    denny65 New Member

    Dec 2, 2012
    killen alabama
    i need to know what wires to cut off and leave off and wat wires to just splice n all that wat not can so one help asap i doin this right now

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