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Anthony
Anthony, ASE Certified Technician
Category: Lexus
Satisfied Customers: 11808
Experience:  ASE Master Automobile Technician with over 20 years exp. in this field.
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1999 lexus rx 300 2wd. knock sensor sub harness. where does

Customer Question

hi. 1999 lexus rx 300 2wd. knock sensor sub harness. where does the sub harness exit the top of the engine block when lower and upper intake manifolds are replaced and where is the connection from sub harness to main harness
Submitted: 2 years ago.
Category: Lexus
Customer: replied 2 years ago.
I have removed the top plastic engine cover (trim panel -- lexus emblem screw fastener plus three (3) allen bolts) - exposing fuel rails, plug coils, etc
Customer: replied 2 years ago.
what color are the leads coming from each of the two knock sensors (oem wiring), how many leads are in the sub harness and what color is the connector on the sub harness side. Then,...what color is the connector on the up-line harness and the lead colors and number of leads going from that up-line connector. I am the first owner of this vehicle and this is factory original.
Expert:  Anthony replied 2 years ago.

Hello!

The knock sensors are under the lower intake. Here's pictures of the sensor location and the wiring diagram. You have to trace the wires to find their locations.

Customer: replied 2 years ago.
Thank you for the prompt reply. I have looked at the two attached schematics and they are unclear. My understanding is that there are bank one and bank two knock sensors on the 99 v six rx 300 2wd ....a total of two sensors. Schematic shows one only. Does the knock sensor sub harness emerge from below the intake manifolds on the drivers side (by cylinder 5) or at the passenger side (by timing belt cover)------as your schematic seems to indicate . I have a po330 code which comes back almost immediately after reset and no O/D. I don't want to spend the time and money to take the top of the engine apart and rr sensors and sub harness and am hoping to be able to trace fault and jump out bad sensor or harness lead in the engine compartment,,,,,,,rather than having to rr glovebox and trace / jump at control module. Number of Factory leads and colors, (at sub harness splice point) and. sub harness mounting position (at exterior of intake manifolds) would be helpfull Other website info indicates bank two sensor traces to black lead at cabin CU and bank one sensor to clear lead, each adjacent to each other at third from top harness block connector jack, at door side of harness plug. Can you confirm that if I need to go at this from the CU please ??
Expert:  Anthony replied 2 years ago.

Hello!

Theres two sensors under the intake. One is on the front cylinder bank of the engine and the other is on the rear cylinder bank under the intake. The wires go out under where the throttle would be. The sub harness starts under the throttle and goes to the two sensor. I have replaced the senors and harness more times that I can count and have never found a fault in the main harness in relation to the code you have. I always just do both sensors and the harness because only the sub harness goes bad and the sensors go bad one at a time so you might as well do both.

Expert:  Anthony replied 2 years ago.

Here's a picture of the sensors in relation to the block. I drew a red line where the harness comes out.