PTC Heater Circuit

AIR CONDITIONING: AIR CONDITIONING SYSTEM: PTC Heater Circuit

PTC Heater Circuit

DESCRIPTION

The GLW RLY turns on when it receives a signal from the A/C amplifier. As a result, power is supplied to the heater glow plug.

WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. INSPECT FUSE (ECU-IG LH, GLW PLG1, GLW PLG2)
(a) Remove the ECU-IG LH fuse from the cowl side junction block LH.
(b) Remove the GLW PLG1 and GLW PLG2 H-fuse from the engine room No. 1 junction block.
(c) Measure the resistance of the fuses.
Standard resistance:






NG -- REPLACE FUSE
OK -- Continue to next step.

2. CHECK AIR CONDITIONING AMPLIFIER




(a) Remove the A/C amplifier with its connectors still connected.
(b) Turn the engine switch on (IG).
(c) While the PTC operating conditions are met (engine is running at 850 rpm or more, ambient temperature is 3°C (37.4°F) or less, engine coolant temperature is 75°C (167°F) or less, A/C switch setting is MAX HOT), turn the blower switch to the Lo setting.
(d) Measure the voltage of the connectors.
Standard voltage:






OK -- REPLACE PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE
NG -- Continue to next step.

3. INSPECT RELAY (GLW RLY1, GLW RLY2)




(a) Remove the GLW RLY1 and GLW RLY2 relays from the engine room No. 4 relay block.
(b) Measure the resistance of the relays.
Standard resistance:






NG -- REPLACE RELAY
OK -- Continue to next step.

4. CHECK WIRE HARNESS (A/C AMPLIFIER - ENGINE ROOM NO. 4 RELAY BLOCK)




(a) Disconnect the K51 and K52 A/C amplifier connector.
(b) Remove the GLW RLY1 and GLW RLY2 relays from the engine room No. 4 relay block.
(c) Measure the resistance of the wire harness side connectors.
Standard resistance:






NG -- REPAIR OR REPLACE HARNESS AND CONNECTOR
OK -- Continue to next step.

5. CHECK WATER BY-PASS GLOW PLUG




(a) Remove the glow plug.
(b) Measure the resistance of the glow plug.
Standard resistance:
Below 1 Ohms
NG -- REPLACE WATER BY-PASS GLOW PLUG
OK -- Continue to next step.

6. INSPECT HEATER BLOWER WIRE




(a) Remove the heater blower wire.
(b) Measure the resistance of the heater blower wire.
Standard resistance:






NG -- REPLACE HEATER BLOWER WIRE
OK -- Continue to next step.

7. CHECK WIRE HARNESS (HEATER BLOWER WIRE - ENGINE ROOM NO.4 RELAY BLOCK)




(a) Disconnect the E78 heater blower wire.
(b) Remove the GLW RLY1 and GLW RLY2 relays from the engine room No. 4 relay block.
(c) Measure the resistance of the wire harness side connectors.
Standard resistance:






NG -- REPAIR OR REPLACE HARNESS AND CONNECTOR
OK -- PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE