T-SB-0009-16 February 4, 2016 CY) TOYOTA

Technical Service Bulletin

High-insulation Fuel Cell Stack Coolant

Service
Category General

Toyota Supports

Section Outline-General Market USA ASE Certification
Applicability

YEAR(S) MODEL(S) ADDITIONAL INFORMATION

2016 Mirai

Introduction

Hydrogen fuel cell powered vehicles like the Mirai use a special high-insulation coolant designed
to prevent high voltage ground faults and associated MIL “ON” (Malfunction Indicator Light)
condition. This special coolant and special water mix MUST be used any time coolant is added to
the fuel cell (FC) cooling system reservoir or when major services are performed on the fuel cell
stack and/or fuel cell cooling system. Use of water or any coolant other than “Toyota Genuine FC
Stack Coolant” could result in damage to the fuel cell stack and/or cooling system.

Parts Information

PART NUMBER PART NAME Qty
08889-80350 FC Stack Coolant Assy. 20L

Precautions

Fuel Cell Coolant

Inspect at specified intervals. When performing inspections, check that the coolant level is
between the “FULL” and “LOW” lines on the see-through reservoir tank.

Use the following product:

e “Toyota Genuine FC Stack Coolant.”
o In order to safely cool the fuel cell stack, which is at high voltages, the fuel cell stack
coolant is an exclusive high insulation product.
Never use water or other kinds of coolants as they will cause damage.
Coolant changes are unnecessary.
Do not reuse coolant that has been removed from the radiator.
Coolant is colorless.

oo 0 6

© 2015 Toyota Motor Sales, USA Page 1 of 2
C2TOYOTA _ T-SB-0009-16 February 4, 2016 Page 2 of 2

High-insulation Fuel Cell Stack Coolant

Procedure

Coolant !evel should be inspected at each service interval to confirm that the coolant level is
between the “FULL” and “LOW” fines on the see-through reservoir tank. If coolant is below the
“LOW" line on the reservoir, ONLY special FC stack coolant should be added.

NOTICE
DO NOT TOP-OFF WITH WATER OR ANY OTHER COOLANT.

Fuel cell stack coolant is a colorless ethylene-glycol product available as a full-service kit
containing 10 liters of FC stack coolant concentrate and 10 liters of special deionized water. The
Full-service Kit requires mixing approximately equal parts of FC stack coolant concentrate with
special deionized water. The coolant concentrate comes in 5 containers each half filled. Add
special deionized water, approximately 2 liters, to fill each container. Do not use any other mixing
container to prevent contamination. A little left over special deionized water is normal.

NOTICE

Freshly mixed coolant has a maximum shelf life of 2 weeks and must be discarded if
NOT used.

If coolant is drained from the FC stack cooling system, DO NOT REUSE. Replace drained FC
stack coolant with new, freshly mixed, “Toyota Genuine FC Stack Coolant”.

NOTICE
Filling the fuel cell cooling system with anything other than FC stack coolant may cause a loss
of high voltage insulation requiring multiple cooling systems flushes to correct.

© 2015 Toyota Motor Sales, USA