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Thread: GMC Cab Lights Leaking

  1. #1
    Join Date
    Oct 2008
    Location
    Washington
    Posts
    5

    Default GMC Cab Lights Leaking

    Does anyone have the new GM part number for the improved cab light lens or good after market lens.

  2. #2
    Join Date
    Mar 2000
    Location
    South Central Pennsylvania, USA
    Posts
    2,697

    Default

    You don't say what year or model truck you have, but I fixed my leaks by taking the lenses and rubber seals off, applying a bead of silicone sealant around the perimeter of the seal between the seal and the cab, and then reassembling. I tightened the lenses down enough to hold things firmly in place and then tightened them down completely after things had a chance to cure.
    '94 GMC 6.5TD K1500 4L80E 2-Door Yukon SLE 221K
    '93 Chevrolet 6.5TD K2500HD NV4500 Std. Cab Longbed 187K
    '85 Toyota 22R RN60 4x4 Std. Cab Shortbed 178K (Currently retired for rebuild)
    Diesel Page Member #2423

  3. #3
    Join Date
    Mar 2007
    Location
    Pacific Northwest
    Posts
    740

    Arrow

    I'll do one better. Here is the whole bulletin. As I remember, this affected the 2003 - early 2007 C series trucks.





    Subject: Water Intrusion into Cab (Inspect/Replace Roof Marker Lamp Lens/Bolts)


    Models: 2003-2006 Chevrolet Kodiak C4500-C8500 Series

    2003-2006 GMC TopKick C4500-C8500 Series

    2005-2006 Isuzu HTR/HVR/HXR Conventional Models




    --------------------------------------------------------------------------------

    This bulletin is being revised to change the torque specification. Please discard Corporate Bulletin Number 05-08-57-004 (Section 08 -- Body and Accessories).


    --------------------------------------------------------------------------------

    Condition
    Some dealers/customers may comment that there is water leaking into the cab after a rainstorm. Water may be present on the headliner and/or the cab floor.

    Cause
    The retaining screws for the roof marker lamp lens may have been overtightened, causing the lens to crack. This may allow water to enter the cab through the lens or the gasket around the retaining screw.

    Correction
    Inspect the lens and the screw/gasket assembly of all the roof marker lamps. If any screw/gasket is damaged, replace the screw(s). If a marker lamp looks cracked, run your fingernail across the top of the crack to determine if it's cracked all the way through. If the marker lamp lens is cracked all the way through, replace the lens. After replacement, tighten the screws to 1 N·m (9 lb in). Do NOT overtighten. Refer to Marker Lamp Lens Replacement - Roof in the Lighting Systems sub-section of SI.

    Parts Information
    Part Number
    Description

    15599040
    Lens, Roof Clearance Lamp

    15995422
    Bolt/Screw, Roof Clearance Lamp Lens
    1998 Chevy k-2500 454 147,000 miles and climbing!

    1993 Pontiac G/A Big Block 3.3 Liter 140,000 miles and still going too!

  4. #4
    Join Date
    Oct 2008
    Location
    Washington
    Posts
    5

    Default

    Thanks for the information, it seems from the Bulletin the cab lights are not leaking between the metal roof and light housing.
    It seems GM is saying the leak is from a cracked lens or gasket between the lens and light housing.

    If this this is correct I will not have to pull the headliner down and remove the complete cab fixture / housing.
    It is a 2007 Topkick
    George:

  5. #5
    Join Date
    Mar 2007
    Location
    Pacific Northwest
    Posts
    740

    Default

    No just look on top of the cab at the lenses. You will probably see that the lenses are cracked.
    1998 Chevy k-2500 454 147,000 miles and climbing!

    1993 Pontiac G/A Big Block 3.3 Liter 140,000 miles and still going too!

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