Lexus NX: Vehicle Speed Signal Circuit between Stereo Component Amplifier and Combination Meter
DESCRIPTION
The stereo component amplifier assembly receives a vehicle speed signal from the combination meter assembly to control the ASL function.
HINT:
- A voltage of 12 V or 5 V is output from each ECU and then input to the combination meter assembly. The signal is changed to a pulse signal at the transistor in the combination meter assembly. Each ECU controls its respective systems based on this pulse signal.
- If a short occurs in any of the ECUs or in the wire harness connected to an ECU, all systems in the diagram below will not operate normally.
WIRING DIAGRAM
PROCEDURE
| 1. | CHECK COMBINATION METER ASSEMBLY (OUTPUT WAVEFORM) |
| (a) Check the output waveform. (1) Remove the combination meter assembly with the connector still connected. (2) Connect an oscilloscope to terminal I10-19 (+S) and body ground. (3) Turn the power switch on (IG). (4) Turn a wheel slowly. (5) Check the signal waveform according to the condition(s) in the table below.
OK: The waveform is similar to that shown in the illustration. HINT: When the system is functioning normally, one wheel revolution generates 4 pulses. As the vehicle speed increases, the width indicated by (A) in the illustration narrows. |
|
| NG | .gif) | GO TO METER / GAUGE SYSTEM |
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| 2. | CHECK HARNESS AND CONNECTOR (STEREO COMPONENT AMPLIFIER ASSEMBLY - COMBINATION METER ASSEMBLY) |
(a) Disconnect the P46 stereo component amplifier assembly connector.
(b) Disconnect the I10 combination meter assembly connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
| Tester Connection | Condition | Specified Condition |
|---|---|---|
| P46-11 (SPD) - I10-19 (+S) | Always | Below 1 Ω |
| OK | | PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE |
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
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System Diagram
SYSTEM DIAGRAM Communication Table Transmitter Receiver Signal Communication Method Air Conditioning Control Assembly Air Conditioning Amplifier Assembly Rear window defogger switch signal LIN
Headlight aim
Vertical movement adjusting
bolts
Type A
Adjustment bolt A
Adjustment bolt B
Type B
Adjustment bolt A
Adjustment bolt B
Before checking the headlight
aim
Make sure the vehicle has a full tank
of gasoline and the area around the
headlight is not deformed.
Park the v
