Park Avenue V6-3.8L VIN K (1995)
Seat Heater: Technical Service Bulletins
Seats - Revised Wiring & Diagnostics, Heated Seat Option
File In Section: 8 - Chassis/Body Electrical
Bulletin No.: 73-81-51
Date: November, 1997
SERVICE MANUAL UPDATE
Subject:
Section 8A - Revised Diagnostics, Schematics,
and Text for Heated Seats
Models:
1995-97 Buick Park Avenue
This bulletin is being issued to revise the heated seats section of the 1997 Service Manual. For schematics and diagnostics, use the 1998 C-Car Service
Manual Electrical Diagnosis Cell 143.
Also, this bulletin provides a revised heated seats section for the 1995 and 1996 C/H Service Manual. Revised schematics and diagnostic charts are
included. Revised text for "Troubleshooting Hints" and "Circuit Operation" is as follows.
Troubleshooting Hints
(Perform before beginning System Diagnosis)
1.
Check I/P Fuse Block IGN (RUN/CRANK) CHIME CLSTR Fuse 1D by visual inspection.
2.
Check Relay Center HTD STS PASS Fuse 9 and HTD STS DRV Fuse 10 by visual inspection.
3.
Make sure that G201 and G202 are clean and tight.
4.
Before component replacement, check for poor connections at related component and in-line harness connector terminal connections.
Check for a broken (or partially broken) wire inside of the insulation which could cause system failure but prove "GOOD" in a continuity/voltage check
with a system disconnected. These circuits may be intermittent or resistive when loaded, and if possible, should be checked by monitoring for a voltage
drop with the system operational (under load).
Check for proper installation of aftermarket electronic equipment which may affect the integrity of other systems.
System Diagnosis
^
Perform the Heated Seats System Check.
Circuit Operation
Battery positive voltage (B+) is applied at all times to the LH heated seat control module from the relay center HTD STS DRV Fuse 10 via CKT 1740
(ORN) and the RH heated seat control module from relay center HTD STS PASS Fuse 9 via CKT 1840 (ORN). Each module receives an ignition input
from the I/P fuse block IGN (RUN/CRANK) CHIME CLSTR Fuse 1D via CKT 39 (BRN). The LH heated seat control module receives ground from
G201 via CKT 1450 (BLK). The RH heated seat control module receives ground from G202 via CKT 1250 (BLK). The system will only operate when
the ignition switch is in RUN.
When the heated seat switch is placed in the LO position, the heated seat control module low temperature switch input is grounded via CKT 1464
(GRY). When the heated seat switch is placed in the HI position, the heated seat control module high temperature switch input is grounded via CKT
1460 (BLK). The heated seat control module then applies battery positive voltage (B+) to the heated seats. The heated seat control module monitors the
seat surface temperature through a thermistor and maintains a pre-determined temperature. The module will also turn off the heated seats whenever the
ignition switch has been turned off.
Temperature Regulation
The heated seat system is designed to warm the seat cushion and backrest to approximately 37°C (98.6°F) when in the low position and 44°C (111.2°F)
when in the high position.
To regulate the temperature of the seats, a temperature sensor is installed in the seat back, called the thermistor. The sensor is a variable resistor (its
resistance changes as the temperature of the seat cushion changes). The heated seat control module monitors the sensor resistance at the sensor input on
connector C2 cavity C. When the heated seat switch is in the LO position and the heating element temperature reaches 37°C (98.6°F), the module opens
its contacts removing battery positive voltage (B+) from the heating elements.
