advisory - gm upfitter bulletin 124d (… · 2014 chevrolet silverado 1500 2015-2016 chevrolet...

UI Bulletin #124d

General Motors Upfitter Integration http://www.gmupfitter.com

Bulletin #124d P a g e 1 April 14, 2016

Disclaimer: GM Upfitter Integration Technical Bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of

conditions that may occur on some vehicles, or to provide information that could assist in the proper service and/or modification of a vehicle. These properly trained technicians

have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or

that your vehicle will have that condition. Contact GM Upfitter Integration for information on whether the information is applicable your vehicle.

Subject: Intermittent Cluster, Radio and HVAC Display Resets on Snow Plow Trucks

Models/Years

Affected:

2014 Chevrolet Silverado 1500 2015-2016 Chevrolet Silverado 2014 GMC Sierra 1500 2015-2016 GMC Sierra With Snow Plow Prep Package (RPO VYU)

Origination Date:

November 30, 2015

Revision

Date: April 14, 2016

ADVISORY:

Notice: GM Dealers refer to Service InformationPIT#5387 for labor code/time information

Condition/Concern:

Trucks equipped with option VYU [Snow Plow Prep] and a snow plow, may

exhibit occurrences in which the Instrument Panel Cluster (IPC), Radio and HVAC displays may “blank out” or reset after changing the snow plow

position. This condition is caused by a system voltage over-shoot phenomenon called ‘load dump’. When the large electrical draw of the plow

pump motor is suddenly removed the field energy that is built up in the

alternator causes a system voltage overshoot that momentarily moves above the normal design operating levels for the module displays. As a result the

displays will shut down or reset causing the momentary blank out condition. The modules are designed to do this and immediately recover. No modules

should be replaced for this condition.

Repair/Recommendation:

Contact your local GM Dealer for an appointment to install PN 84043394 VYU

Snow Plow Jumper harness per GM Service Bulletin PIT#5387.

Note: Your truck may already have the factory harness included as a loose part [in

the glove box]. If not, the jumper harness and installation will be provided [one

time] without charge. Installation charges will be waived only if the jumper is

installed at your GM dealer. If your truck was delivered with the harness you have

the option of having your snow plow dealer install it or you could do it yourself.

These installation costs would not be covered by GM.

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Installation Instructions:

1. Single alternator systems:

a) Unplug the 2-way connector on the alternator.

b) Identify the master alternator connector [at the very tip of the harness

when it is fully extended.] Insert it in the alternator.

c) Take the original alternator connector and plug it into the mating jumper

harness connector. Note: In this case the second alternator connector will

be unused and will remain capped and tied to the harness bundle.

2. Dual alternator systems:

a) Unplug the control connectors on both alternators. Take the original

master alternator connector and plug it into the mating jumper harness

connector.

b) Identify the master alternator connector [at the very tip of the harness

when it is fully extended.] Insert it in the alternator on the RH side of the

engine.

c) Identify the ‘slave’ alternator connector on the jumper harness and insert

it in the LH alternator. Insert the removed LH alternator connector into the

[unwired] cap on the jumper harness.

3. All systems:

a) Route the snow plow jumper harness along the existing harness routing

as shown and secure with tie straps as appropriate.

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b) Mount the relay to the underside of the fender inner at the pencil brace

bolt slipping the relay bracket over the threads and securing it with the nut

provided in the harness kit.

c) Further secure the relay bracket with a tie strap through the remaining

bracket hole to the pencil brace.

d) Locate appropriate connection points for the fused [+] red/orange

harness control wire and the black ground wire.

Note [1]: The appropriate plow control signal should be able illuminate a

test lamp when the plow motor is running and the lamp should go out when

the motor is not running. The jumper relay must be energized at the same

time that the plow motor is.

Note [2]: If this connection point is the coil of the motor power solenoid and

both terminals are hot [B+] when the motor is not running – monitor them

and discover which terminal goes to ground when the motor is running.

The one that goes to ground is the connection point for the black wire – the

one that stays at [B+] is the connection point for the fused wire.

e) For plows with all the control components mounted on the plow itself

Route the relay coil wires [blunt cuts] out through the grille to the

appropriate location to complete the required connections. See notes 1

and 2 in item d) above to correctly identify the connection points.

Note [3]: A pair of capped and sealed 2-way connectors must be installed so

the plow can be mounted and removed at will. M 2W = GM service kit

19119346. F 2W = GM service kit 19119765. 2 sets would be required so

caps can be fashioned from the extra parts .

4.

UI Bulletin #124d







Note [4]: Some manufacturers of these style plows have an inexpensive

jumper harnesses [with a set of sealed connectors] and installation

instructions available to make this connection task easier.

f) For plows with the main hydraulic motor power solenoid mounted under

hood

Find the motor control solenoid and determine if one or both of the harness

control wires can be attached to it. See notes [1] and [2] above to correctly

identify the connection points you will use.

g) Route all wiring away from heat sources and any conditions that could

harm the wiring over time. Attach the jumper harness to existing wiring

bundle [with tie straps and edge clips provided] as per drawings below.

Allow slack for engine roll and vibration.

Note: This change will reduce the potential for the cluster/radio reset issue. It is still possible if the battery is very cold and the alternator voltage is very high that the first time the plow is cycled you might still see the symptom. Adding more electrical loads and reducing RPMs when releasing the control will help.

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Additional Reference Information

Fig 1: Jumper harness wiring schematic

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Fig: 2 Jumper Harness - Component Details

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Fig: 3 Jumper Harness Layouts

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Layout Details

1. Primary Alternator

2. Slave Alternator

3. Relay

4. Wires to plow [fused + & ground]

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Detail 1

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Detail 2

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Detail 3

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Detail 4

Sealed 2 Way connector set [with caps] must be added if the harness goes

out to the plow. M 2W = GM service kit 19119346. F 2W = GM service kit

19119765. Caps can be fashioned from the extra parts. See plow manufacturer for

connection kits.

advisory - gm upfitter bulletin 124d (… · 2014 chevrolet silverado 1500 2015-2016 chevrolet...

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