Positive Temperature Coefficient Heater

2001 ENGINE PERFORMANCE Theory & Operation

ECHO

Positive Temperature Coefficient (PTC) heater is a small electrical heater located in the heater core and is used on vehicles equipped for cold areas. See Fig. 78 . PTC heater may be turned on if all of the following conditions exist: temperature control switch is at MAX HOT position, engine speed is more than 1050 RPM, engine coolant temperature is less than 176°F (80°C) and generator power ratio is less than 95 percent. PTC heater may also be turned on and off depending on generator power ratio.

Temperature control switch operates a maximum hot switch, which provides an input signal to Engine Control Module (ECM) for controlling PTC heater operation. Maximum hot switch may also be referred to as MAX HOT switch.

HTR SUB1 relay is used for supplying battery voltage to PTC heater. HTR SUB1 relay may also be referred to as heater sub relay. HTR SUB1 fuse supplies battery voltage to one side of HTR SUB1 relay. When ignition is turned on, voltage is supplied from ignition switch, through ECU-IG fuse and to other side of HTR SUB1 relay. When PTC amplifier completes ground circuit for HTR SUB1 relay, HTR SUB1 relay then provides battery voltage to PTC heater for PTC heater operation. HTR SUB1 relay is located in fuse/relay box at driver's side front corner of engine compartment, just in front of strut tower.

2001 ENGINE PERFORMANCE Theory & Operation

Hilux Ptc Heater What
Fig. 78: Locating Positive Temperature Coefficient Heater (ECHO) Courtesy of TOYOTA MOTOR SALES, U.S.A., INC.

Was this article helpful?

+1 0
Do It Yourself Car Diagnosis

Do It Yourself Car Diagnosis

Don't pay hundreds of dollars to find out what is wrong with your car. This book is dedicated to helping the do it yourself home and independent technician understand and use OBD-II technology to diagnose and repair their own vehicles.

Get My Free Ebook


Responses

  • luana fanucci
    What is a positive temperature coefficient heater engine?
    8 years ago
  • jaska
    How to fix front heater of 2001 toyota sequoia?
    8 years ago
  • Eric Frueh
    What is htr relay in toyota hilux?
    5 years ago
  • lillie
    What is meaning of ptc realy?
    3 years ago
  • myles
    What is ptc heater prado?
    3 years ago
  • ruben
    What does a ptc heater on a hilux do?
    2 years ago
  • sanni
    What is toyota landcruiser PTC heater?
    1 year ago
  • calum macleod
    What does a HTR relay do toyota landcruiser?
    8 months ago

Post a comment