Hi everyone, I've been struggling for several days with the glow plug preheat circuit on my LJ73, whose 2LT engine I replaced with a 1KZT 7 years ago. This problem started occurring a month ago. The preheat light would come on and off, and there was no power to the glow plug bridge, so I ended up starting it by connecting a direct cable from the battery.
Studying the operation of the circuit as well as the electronic circuit, I discovered some things that I would like to share.
The relays operate if and only if the preheat light comes on. If this doesn't happen, the circuit doesn't close, so a burned-out bulb would prevent the circuit from sending power to the relays.
This is the conector 13 pin´s
(*) Number pin connector
TEMPERATURE SENSOR - pin 10 - pin 7. There should be a resistance between these pins, as indicated by the curve on the right.
1kzt 89422-20010 is listed in Toyodiy as an oil temperature sensor.
GLOW PLUG direct- pin 6, FL (fuse link) delivers 12V.
IGNITION - pin 4. Should receive 12 volts when the ignition is on; it turns on the glow plug light on the dash.
ALTERNATOR L - pin 9. This goes to the L terminal on the alternator, or to the charging fuse. It will have ground continuity when the engine is off and no continuity when the engine is running.
GROUND - pin 10. This pin is also connected to a wire coming from the coolant temperature sensor; it simply goes to a body ground.
STARTER - pin 11. This will receive 12 volts when the starter motor is engaged.
TEST
Studying the operation of the circuit as well as the electronic circuit, I discovered some things that I would like to share.
The relays operate if and only if the preheat light comes on. If this doesn't happen, the circuit doesn't close, so a burned-out bulb would prevent the circuit from sending power to the relays.
This is the conector 13 pin´s
BLACK-BLUE | BLACK-RED | BLACK-YELLOW | lock connector | RED-WHITE | not | BLACK-ORANGE |
| | BLACK-WHITE | BROWN | YELLOW | not | YELLOW |
| 6 F28 Glow Plug (direct) | 5 Glow Plug Relay (2) | 4 Glow indicator Light (1) | lock CONNECTOR | 3 Glow indicator Light (2) | 2 not | 1 Main Relay (2) |
| 13 not | 12 not | 11 Start Fuse | 10 Water temp sensor(1) + masa | 9 Alternator | 8 not | 7 Water temp sensor (2) |
TEMPERATURE SENSOR - pin 10 - pin 7. There should be a resistance between these pins, as indicated by the curve on the right.
1kzt 89422-20010 is listed in Toyodiy as an oil temperature sensor.
GLOW PLUG direct- pin 6, FL (fuse link) delivers 12V.
IGNITION - pin 4. Should receive 12 volts when the ignition is on; it turns on the glow plug light on the dash.
ALTERNATOR L - pin 9. This goes to the L terminal on the alternator, or to the charging fuse. It will have ground continuity when the engine is off and no continuity when the engine is running.
GROUND - pin 10. This pin is also connected to a wire coming from the coolant temperature sensor; it simply goes to a body ground.
STARTER - pin 11. This will receive 12 volts when the starter motor is engaged.
TEST
