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Great deal, but need help with

Discussion in 'The Garage' started by loonatic72, Sep 21, 2006.

  1. loonatic72

    loonatic72 Registered Member

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    I found a 84 cucv p/u last night and bought it for the price of what the owner had in the new tires (less than $500.) It's a 6.2 diesel and the body is about perfect with the exception of a little rust on the rockers. BUT someone tried to convert it from 24v to 12v and it's only getting 6v. Does anyone know exactly what's going wrong or have wiring ideas so I can get this working correctly?? I figured if I could find a wiring diagram I could fix it but I would have to find one for a 12v conversion or just convert it back to 24v. Which do yall think is the best??
     
  2. bear76

    bear76 1/2 ton status

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  3. loonatic72

    loonatic72 Registered Member

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    I tried opening the link above a couple of times on two different computers and it wont open. Is there something im doing wrong or is the link missing something??

    Thanks
     
  4. dontoe

    dontoe 3/4 ton status GMOTM Winner

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  5. dontoe

    dontoe 3/4 ton status GMOTM Winner

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    Location:
    Hickory, N.C.
    The Commercial Utility Cargo Vehicles (CUCV)
    are commercial vehicles modified to meet the
    needs of the U.S. Military. These vehicles come
    in five basic configurations: Cargo, utility,
    ambulance, shelter carrier, and chassis
    versions.
    In the late 70’s and early 80’s, Dodge Division,
    Chrysler Corporation produced the CUCV units.
    In the late 80’s General Motors (GM) produced
    them. The GM versions are the latest of the five
    CUCV variants. The GM models are named, the
    M1008 (Cargo), M1009 (Utility), M1010
    (Ambulance), M1028 (Shelter Carrier), and
    M1031 (Chassis). This report will concern itself
    with the electrical systems of the M1008, which
    is a diesel GM pickup truck, and the M1009,
    known in its civilian life as the Chevrolet
    Blazer/GMC Jimmy.
    The M1008/M1009 were originally designed for
    civilian use, their heritage includes a 12-volt
    electric system. The military, of course, uses
    24-volt electric appliances. Because of this,
    General Motors made some changes to the
    electrical systems of these military models.
    There are two alternators and two batteries,
    each of which is 12-volt. The alternators and
    batteries are connected in series to create 24-
    volts. The driver’s side alternator charges the
    vehicle’s front battery. This battery and
    alternator supply power for all the 12-volt
    components/systems. Both alternators charge
    the rear battery.
    The electrical system of the M1008/M1009 is a
    civilian 12-volt system modified to allow 24-volt
    starting and supply 24-volts for military
    accessories. The only true 24-volt component is
    the starter motor.
    REC Newsnote #10 January 1999​
    Conversion of M1008 and M1009
    Electric Systems to 12 Volt​
    Roscommon Equipment Center​
    Northeast Forest Fire Supervisors​
    in Cooperation with​
    Michigan’s Forest Fire Experiment Station​
    Rear
    Battery
    Positive Terminal Junction Block
    Front
    Battery
    Glow Plug
    Resistors
    Alternators​
    M1008/M1009 Engine Compartment​
    The glow plugs and glow plug relay are 12-volt
    components. Their 24-volt power supply is
    reduced to 12-volt by the use of a resistor bank.
    All running lights, interior lights, and gauges are
    12-volt components
    As you can see, General Motors modified what
    was designed as a 12-volt system into a quasi-
    24 volt system for the military. Converting it
    back to a 12-volt system is neither costly nor
    difficult. The M1008/M1009 electrical system
    can be utilized in one of three ways.​
    1. Retain the system as is.​
    Advantages:​
    a) No cost or labor incurred.
    Disadvantages:
    a) Starter motor is 24-volt. It will be costly and
    difficult to find a replacement.
    b) The positive terminal junction block is 24-volt
    and is unusable for 12-volt add on
    components. (On the M1009, another
    positive terminal junction block is mounted
    on the passenger’s sidewall in the rear seat
    area. This will also be a 24-volt supply.)
    c) The bottom fuse on the vehicle’s fuse panel
    is 24 volt and is unusable for 12-volt add on
    components.
    d) The alternators, although 12 volt, have a
    special isolated ground. These will be costly
    and it will be difficult to find replacements.​
    e) ​
    All 12-volt components including add-ons run
    off the front battery only. This may cause a
    battery imbalance if the engine is not running
    or the 12-volt electrical load is higher than
    the alternator output.

    2. Convert to a 12-volt system utilizing two
    batteries for starting power and one
    alternator for charging. ​
    (Note: Leaving
    both alternators has little or no benefit.
    Unless the voltage regulators’ turn on points
    are identical, only one alternator will be
    utilized by the system.)
    Advantages:

    a) Single voltage system.
    b) All electrical component replacement parts
    are readily available.
    c) Alternator to be removed can be used as
    replacement part for remaining alternator.
    d) Commercial (non-isolated ground) alternator
    can be used for replacement. Just remove
    ground wire from system.
    e) Both front and rear positive terminal junction
    blocks (rear available on M1009 only) and
    the bottom fuse of the fuse panel can be
    used as non-isolated 12-volt power supplies.
    Disadvantages:
    a) Fire apparatus (i.e. hose reel rewind and
    pump start) work directly from starting
    batteries.​
    b) ​
    Some cost (12-volt starter and wiring
    supplies) and labor occurred.

    3. Convert to two 12-volt isolated systems.
    One system utilizing the two existing
    batteries and one alternator. The second
    system utilizing the other alternator and
    an additional battery.​
    Advantages:​
    a) Single voltage system.
    b) All electrical components readily available.
    c) Alternator to be removed can be used as
    replacement part for remaining alternator.
    d) Commercial (non-isolated ground) alternator
    can be used for replacement. Just remove
    ground wire from system.
    e) Both front and rear positive terminal junction
    blocks (rear available on M1009 only) and
    the bottom fuse of the fuse panel can be
    used as non-isolated 12-volt power supplies.
    f) Fire apparatus (i.e. hose reel rewind and
    pump start) and accessories electrical load
    may be isolated from starting batteries.
    Disadvantages:
    a) Some cost (12-volt starter, third battery, and
    wiring supplies) and labor occurred.​
    We feel that systems 2 and 3 have the most
    merit. System 2 is simple and suitable if large
    electrical accessory loads are not expected.
    System 3 isolates the vehicle’s electrical system
    from the large electrical accessory loads that
    can be imposed by fire apparatus. This helps
    protect against inadvertent drainage of the
    vehicle’s electrical power for starting.
    The following directions will step through the
    conversion of the CUCV electric system to a
    single 12-volt system or two separate isolated
    12-volt systems.
    - 2 -​
    M1008/M1009 Conversion to 12-Volt system​
    These instructions are a guide to convert the
    military electrical system of a M1008 or M1009
    to a 12-volt system charged by a single
    alternator. The passenger side alternator will be
    used to charge both of the vehicle's batteries.
    The driver side alternator will be removed.
    1. Disconnect the ground wire from the
    negative (-) terminal of the front battery.
    2. Remove the jumper cable that connects the
    front battery's positive (+) terminal to the
    rear battery's negative (-) terminal. Cut the
    8 gauge red wire from the rear batteries
    negative (-) terminal. This wire will be used
    in the next step (Photo 1).
    3. Add a 1/4 inch ring terminal to the 8 Ga. red
    wire that was cut in the previous step and
    replace the terminal on the fusible link end
    with a 5/16 inch ring terminal. Reinstall the
    wire attaching the fusible link end to a post
    on the positive (+) terminal junction block
    the other end connects to the larger stud on
    the 12 volt junction block (Photo 2 and 3).
    4. With the air cleaner removed, remove the
    resistors located on upper center of the
    firewall. The resistors are mounted on the
    backside of black sheet metal mounting
    bracket. Three hex head screws mount the
    sheet metal bracket to the firewall. Remove
    these to access the resistors (Photo 2).
    5. An 8 gauge wire connects the positive (+)
    terminal junction block to the resistors.
    Another 8 gauge wire connects the resistors
    to the glow plug relay. Disconnect these
    from the resistors. Remove the wire that
    runs from the resistors to the glow plug
    relay. Extend the wire that runs from the
    positive (+) terminal junction block to the
    resistors so that it is long enough to reach
    the glow plug relay (insulate the splice)
    (Photo 3).​
    Caution: ​
    A new wire may be used to replace
    the existing wire but the existing wire
    has a fusible link at the end for short
    circuit protection. If a new wire is
    installed, short circuit protection
    should be installed as close as
    possible to the end connected to the
    positive (+) terminal junction block.

    Jumper Cable
    Passenger
    Side Alternator
    8 Ga. Wire​
    Photo 1​
    - 3 -
    6. Disconnect the wire from the ground
    terminal on passenger side alternator,
    insulate the end, bend the wire back, and
    secure it to the harness. This is an 8 gauge
    red wire with a white tracer. (The tracer may
    be hard to locate.) (Photo 4).
    7. Add a ground wire from the ground terminal
    of the passenger’s side alternator to the
    engine. The wire removed in Step 12 can
    be used.
    8. Remove the condenser mounted to the rear
    of the passenger side alternator. This is the
    cylindrical part with one wire (Photo 4).
    Positive (+) Terminal
    Junction Block
    Resistor
    Bracket
    Negative (-) Terminal
    Junction Block​
    Photo 2​
    12 Volt
    Junction
    Block
    Glow Plug Relay
    Brake System
    Master Cylinder
    Red 14 Ga.
    Wire with
    Brownish-
    Orange
    Fusible Link​
    Photo 3​
    - 4 -
    9. The two alternators are connected together
    at the 12-volt junction block. The two red 8
    gauge wires come together into one ring
    terminal on the larger stud of the 12-volt
    junction block. (On the unit done by REC
    these wires had blue fusible links on the
    end.) Disconnect these wires from the 12-
    volt junction block (Photo 3).
    10. On the smaller stud of the 12-volt junction
    block a red 14 gauge Wire is attached. (On
    the unit done by REC, this wire had a
    brownish-orange fusible link on the end.)
    Disconnect this wire from the 12-volt
    junction block (Photo 3).
    11. Insulate the ends of the wires removed in
    the two previous steps, bend the wires back,
    and secure them to the harness.
    12. Remove the ground wire that connects the
    driver’s side alternator to the engine (Photo
    5).​
    Wire Attached to
    Ground Terminal
    Condenser
    Passenger
    Side Alternator​
    Photo 4​
    Driver Side
    Alternator
    Ground
    Wire​
    Photo 5​
    - 5 -
    13. Disconnect all the remaining wires that
    connect to the rear of the driver’s side
    alternator, insulate the ends of each wire,
    bend the wires back, and secure them to the
    harness.
    14. Remove the driver’s side alternator, its
    mounting bracket and hardware, and its
    drive belt.
    15. Remove 24-volt starter and replace with 12-
    volt starter. The starter is shimmed for
    proper gear engagement the replacement
    starter may require different shimming.
    16. Connect the positive (+) terminal of the front
    battery to the positive terminal of the rear
    battery. (Use 4 gauge wire minimum.) The
    positive terminal of the rear battery should
    still be connected to the positive junction
    block (Photo 6).
    17. Ground the rear battery to the negative (-)
    terminal junction block. (Use 4 gauge wire
    minimum.)
    18. Reconnect the ground wire to negative (-)
    terminal of front battery.​
    Ground to Negative
    (-) Terminal
    Junction Block
    Connection Between
    Positive (+) Terminals
    on Batteries​
    Photo 6​
    - 6 -​
    M1008/M1009 Conversion to Two 12 Volt Isolated Systems​
    These instructions are a guide to convert the
    military electrical system of a M1008 or M1009
    to two separate 12-volt systems each charged
    by a single alternator. The passenger side
    alternator will be used to charge both of the
    vehicle's batteries. The driver side alternator will
    be used to charge a battery on an auxiliary
    system.
    1. Disconnect the ground wire from the
    negative (-) terminal of the front battery.
    2. Remove the jumper cable that connects the
    front battery's positive (+) terminal to the
    rear battery's negative (-) terminal. Cut the
    8 gauge red wire from the rear batteries
    negative (-) terminal. This wire will be used
    in the next step (Photo A).
    3. Add a 1/4 inch ring terminal to the 8 gauge
    red wire that was cut in the previous step
    and replace the terminal on the fusible link
    end with a 5/16 inch ring terminal. Reinstall
    the wire attaching the fusible link end to a
    post on the positive (+) terminal junction
    block the other end connects to the larger
    stud on the 12-volt junction block (Photo B
    and C).​
    Positive (+) Terminal
    Junction Block
    Resistor
    Bracket
    Negative (-) Terminal
    Junction Block​
    Photo B​
    Jumper Cable
    Passenger
    Side Alternator
    8 Ga. Wire​
    Photo A​
    - 7 -
    4. With the air cleaner removed, remove the
    resistors located on upper center of the
    firewall. The resistors are mounted on the
    backside of black sheet metal mounting
    bracket. Three hex head screws mount the
    sheet metal bracket to the firewall. Remove
    these to access the resistors (Photo B).
    5. An 8 gauge wire connects the positive (+)
    terminal junction block to the resistors.
    Another 8 gauge wire connects the resistors
    to the glow plug relay. Disconnect these
    from the resistors. Remove the wire that
    runs from the resistors to the glow plug
    relay. Extend the wire that runs from the
    positive (+) terminal junction block to the
    resistors so that it is long enough to reach
    the glow plug relay (insulate the splice)
    (Photo C).​
    Caution: ​
    A new wire may be used to replace
    the existing wire but the existing wire
    has a fusible link at the end for short
    circuit protection. If a new wire is
    installed, short circuit protection
    should be installed as close as
    possible to the end connected to the
    positive (+) terminal junction block.

    6. Disconnect the wire from the ground
    terminal on passenger side alternator,
    insulate the end, bend the wire back, and
    secure it to the harness. This is an 8 gauge
    red wire with a white tracer. (The tracer may
    be hard to locate.) (Photo D).
    7. Add a ground wire from the ground terminal
    of the passenger’s side alternator to the
    engine.
    8. Remove the condenser mounted to the rear
    of the passenger’s side alternator. This is
    the cylindrical part with one wire (Photo D).
    9. The two alternators are connected together
    at the 12-volt junction block. The two red 8
    gauge wires come together into one ring
    terminal on the larger stud of the 12-volt
    junction block. (On the unit done by REC,
    these wires had blue fusible links on the
    end.) Disconnect these wires from the 12-
    volt junction block (Photo C).
    10. On the smaller stud of the 12-volt junction
    block, a red 14 gauge wire is attached. (On
    the unit done by REC, this wire had a
    brownish-orange fusible link on the end.)
    Disconnect this wire from the 12-volt
    junction block (Photo C).
    11. Connect the wires removed in the two
    previous steps to a 50-amp circuit
    breaker/fuse mounted close to the 12-volt
    junction block. The terminals of this circuit
    breaker/fuse need to insulated or isolated
    from accidental contact when working in
    engine the compartment (Photo E).​
    12 Volt
    Junction
    Block
    Glow Plug Relay
    Brake System
    Master Cylinder
    Red 14 Ga.
    Wire with
    Brownish-
    Orange
    Fusible Link​
    Photo C​
    - 8 -
    12. Connect the auxiliary system charging wire
    (8 gauge wire minimum) to the other
    terminal of the circuit breaker/fuse. This
    wire should run back to a second 50-amp
    circuit breaker/fuse near where a third
    battery is to be mounted. The terminals of
    this circuit breaker/fuse need to insulated or
    isolated from accidental contact.
    13. A power supply wire (8 gauge minimum) to
    an auxiliary fuse panel can be attached to
    same terminal of either 50-amp circuit
    breaker/fuse as the auxiliary system
    charging wire.
    14. Add a wire (8 gauge minimum) to connect
    the open terminal of the second circuit
    breaker/fuse to the positive (+) terminal of
    the third battery.
    15. Remove 24-volt starter and replace with 12-
    volt starter. The starter is shimmed for
    proper gear engagement the replacement
    starter may require different shimming.​
    Circuit
    Breaker/Fuse
    12 Volt Junction Block
    Auxiliary System
    Charging Wire
    Rerouted
    Wires​
    Photo E​
    Wire Attached to
    Ground Terminal
    Condenser
    Passenger
    Side Alternator​
    Photo D​
    - 9 -
    16. Connect the positive (+) terminal of the front
    battery to the positive terminal of the rear
    battery. (Use 4 gauge wire minimum.) The
    positive terminal of the rear battery should
    still be connected to the positive junction
    block (Photo F).
    17. Ground the third battery to the chassis.
    (Use 4 gauge wire minimum.)
    18. Ground the rear battery to the negative (-)
    terminal junction block. (Use 4 gauge wire
    minimum.)
    19. Reconnect the ground wire to negative (-)
    terminal of front battery.​
    Ground to Negative
    (-) Terminal
    Junction Block
    Connection Between
    Positive (+) Terminals
    on Batteries​
    Photo F​
    - 10 -​
     
  6. loonatic72

    loonatic72 Registered Member

    Joined:
    May 29, 2006
    Posts:
    36
    Likes Received:
    0
    Location:
    North Carolina
    Thanks man, my computer was just hiding adobe and didn't want to open it. I got it open now. Thanks for the help now all I have to do is run down and put the truck on my trailer and bring it home.
     

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