Service Update
18185 Coolant Concentration Out of Specification
Reference Number:
Attention:

N182166550

Release Date:
Revision:

May 2018
00

This service update includes vehicles in dealer inventory and customer vehicles that return to the
dealership for any reason. This bulletin will expire at the end of the involved vehicle’s New Vehicle Limited
Warranty period.

Make
Chevrolet
GMC

Model
Silverado
Sierra

Model Year
From
To
2018
2018

RPO

Description

Involved vehicles are marked “open” on the Investigate Vehicle History screen in GM Global Warranty Management
system. This site should always be checked to confirm vehicle involvement prior to beginning any required inspections
and/or repairs.
Condition

Correction

In certain 2018 model year Chevrolet Silverado and GMC Sierra vehicles, the concentration of dex-cool
coolant to water may be too high and may cause degradation of cooling performance. The driver may
see a DIC message at 125 degrees Celsius that the air-conditioning is disabled for engine coolant
temperature (ECT), and at 128 degrees Celsius, another DIC message is displayed for Engine
Overheated Idle Engine.
Dealers are to drain specified coolant amount and replace with water.

Parts
No parts are required for this repair.
Warranty Information
Labor
Operation
9103836

Labor
Time
0.5

Description
Drain Coolant and Add Water

Trans.
Type
ZFAT

Net
Item
N/A

Service Procedure
Warning: To avoid being burned, do not remove the radiator cap or surge tank cap while the engine is hot. The
cooling system will release scalding fluid and steam under pressure if radiator cap or surge tank cap is removed
while the engine and radiator are still hot.
1.

Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in SI.

5084298
2.

Place a drain pan under the radiator drain cock.

3.

Install a suitable length of hose to the radiator drain cock nipple and route the hose to allow free drain of coolant.

4.

Open the radiator drain cock.

5.

Using the chart below, drain the appropriate amount of coolant.

6.

Close the radiator drain cock and remove hose.

Copyright 2018 General Motors. All Rights Reserved.

Page 1 of 2

Service Update
18185 Coolant Concentration Out of Specification
7.

Lower the vehicle. Refer to Lifting and Jacking the Vehicle in SI.

8.

Open the hood and install fender covers.

9.

Remove the radiator surge tank cap.

5084299
10. Using a funnel, fill the surge tank with the correct amount of clean, drinkable water.
11. Install the radiator surge cap.
12. Remove the fender covers and close hood.
Coolant Chart
Engine RPO

Amount of Coolant to Drain/Water to be added

LV3 (4.3L)

3.9 Liters

L83 (5.3L)

4.2 Liters

L96 (6.0L)

4.4 Liters

L86 (6.2L)

4.2 Liters

Dealer Responsibility
Whenever a vehicle subject to this service update enters your vehicle inventory, or is in your facility for service in the
future, and the vehicle is still covered under the New Vehicle Limited Warranty, you must take the steps necessary to be
sure the service update correction has been made before selling or releasing the vehicle.
All new, used, GM Certified Used, courtesy transportation vehicles, dealer shuttle vehicles, etc. in dealers' possession
and subject to this bulletin must be held and inspected/repaired per the service procedure of this bulletin before customers
take possession of these vehicles. Involved vehicles must be held and not delivered to customers, dealer-traded,
released to auction, used for demonstration, or any other purpose.
All GM Certified Used vehicles currently in the dealers’ inventory within the Certified Pre-Owned Inventory System
(CPOIS) will be de-certified and must be held and remedied per the service procedure in this bulletin. Upon submitting
an accepted/paid warranty transaction in the Global Warranty Management (GWM) system, the vehicle can be re-certified
for sale within the CPOIS system, or once again be used in the CTP program.

GM 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 of a vehicle. Properly trained
technicians have the tools, equipment, 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. See your dealer for information on whether your
vehicle may benefit from the information.

We Support
Voluntary Technician
Certification

Page 2 of 2

GLOBAL SAFETY FIELD INVESTIGATIONS
DCS4765
URGENT - DISTRIBUTE IMMEDIATELY
Date:

May 30, 2018

Subject: 18185 - Service Update
Coolant Concentration Out of Specification
Models: 2018 Chevrolet Silverado
2018 GMC Sierra
To:

All General Motors Dealers

General Motors is releasing Service Update 18185 today. The total number of
U.S. vehicles involved is approximately 39. Please see the attached bulletin
for details.
Global Warranty Management (GWM)
The Investigate Vehicle History (IVH) screen in the GWM system will be updated today,
May 30, 2018. A list of involved vehicles in dealer new inventory is attached to this
message. Please hold all warranty transactions until IVH has been updated.
END OF MESSAGE
GLOBAL SAFETY FIELD INVESTIGATIONS