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Fix for faulty flashing.

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FMTV trucks with serial numbers 100,001 to 115,482 need a new K-10 relay. That's because these newer production 2 1/2- and 5-ton FMTV trucks equipped with LED service light switches have a problem with unexpected flashing of the front turn signals.

Fortunately, older model FMTV trucks with mechanical-type light switches and incandescent turn signal light bulbs are not affected.

The faulty front turn signal flashing happens when the ignition switch is placed in the ON position, the engine is running, the air pressure is in the normal range and the service lights are in blackout mode. The front turn signal lights will flash once each time the operator releases brake pedal pressure.

New K-10 Relay

The culprit is the K-10 relay located in the passenger side power distribution panel (PDP). It doesn't operate correctly in that circuit, so the front turn signal lights flash.

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A NEW REPLACEMENT RELAY IS AVAILABLE TO CORRECT THIS PROBLEM.

REPLACEMENT K-10 RELAYS ARE IDENTIFIED BY A BLUE MARKING ON TOP.

THESE RELAYS WILL ALSO HAVE ANY ONE OF THE FOLLOWING VENDOR PART NUMBERS STAMPED ON THEM ...

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PN 2802 (CAGE 5J417)

PN 301-1C-S-D1 (CAGE 1HKM2)

PN 301-1C-C-D1 (CAGE 1HKM2)

PN ACV12112 (CAGE 0J4G8)

Removal and Replacement

Use your FMTV truck's IETM, EM 0195, to get to the maintenance procedures found in TM 9-2320-392-20. Then follow these steps to remove and replace the K-10 relay and fix the faulty flashing:

1. Set the external master manual battery disconnect switch to OFF.

2. Make sure the service light switch is set to OFF.

3. Remove the PDP using the Power Distribution Panel Replacement (PDPR) procedures in your IETM.

4. Open the module 2 relay panel cover using EM 0195's Circuit Breaker and Relay Replacement Work Package.

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5. Remove the old K-10 relay, NSN 5945-01-527-6667 and PN G8V-1C7T-R-DC12, and replace it with the new relay, NSN 5945-01-557-4666 and PN 12424852. This relay location is referenced on the outside of the relay panel cover as K10/12V/ Stop/Hazard.

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6. Close the number 2 PDP relay module cover and reinstall the PDP cover.

7. Place the external batteries switch to ON.

Operational Light Check

Next, conduct an operational light check following these steps:

1. Start your truck's engine with the transmission in NEUTRAL.

2. Allow the air tanks to build up normal operating pressure.

3. Get someone to stand outside the truck, in a safe position, to observe the front turn signals.

4. Put the service lights in blackout mode.

5. Press and hold the brake pedal.

6. Release the brake pedal pressure while the observer you tagged in step three watches the front turn signals. The turn signal lights should not illuminate or flash.

You've Got a Spare

The K-10 relay you removed is also used in other circuits throughout the power distribution modules. That means you can use them as spares.

And look for a future update to EM O195 (TM 9-2320-392-20). It'll give you updated NSN and PN information.

This info is also found in TACOM MAM 08-032. You can download it on the AEPS website using this link:

https://aeps2.ria.army.mil/commodity/Mam/Tacom_WN/08/mam08-032.html
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Title Annotation:FMTV ...; family of medium tactical vehicles
Publication:PS, the Preventive Maintenance Monthly
Geographic Code:1USA
Date:Feb 1, 2009
Words:539
Previous Article:New 24-bolt wheel / rim assembly.
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