Lexus NX: Vehicle Speed Signal Circuit between Navigation ECU and Combination Meter
DESCRIPTION
The navigation ECU receives a vehicle speed signal from the combination meter assembly.
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. |
|
.png)
| NG | .gif) | GO TO METER / GAUGE SYSTEM |
.gif)
|
.gif)
| 2. | CHECK HARNESS AND CONNECTOR (NAVIGATION ECU - COMBINATION METER ASSEMBLY) |
(a) Disconnect the I173 navigation ECU 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 |
|---|---|---|
| I173-9 (SPD) - I10-9 (+S) | Always | Below 1 Ω |
| OK | | PROCEED TO NEXT SUSPECTED AREA SHOWN IN PROBLEM SYMPTOMS TABLE |
| NG | | REPAIR OR REPLACE HARNESS OR CONNECTOR |
READ NEXT:
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 ea
Reverse Signal Circuit between Radio Receiver Assembly and Navigation ECU
DESCRIPTION This circuit includes the navigation ECU and radio and display receiver assembly. WIRING DIAGRAM PROCEDURE 1. CHECK HARNESS AND CONNECTOR (RADIO RECEIVER ASSEMBLY - NAVIGATION ECU)
Start Up Signal Circuit between Radio Receiver Assembly and Navigation ECU
DESCRIPTION This circuit includes the navigation ECU and radio and display receiver assembly. WIRING DIAGRAM PROCEDURE 1. CHECK HARNESS AND CONNECTOR (RADIO RECEIVER ASSEMBLY - NAVIGATION ECU)
SEE MORE:
Disc cannot be Ejected
CAUTION / NOTICE / HINT NOTICE: When replacing the radio receiver assembly, always replace it with a new one. If a radio receiver assembly which was installed to another vehicle is used, the following may occur:
A communication malfunction DTC may be stored.
The radio receiver assembly may not
Installation
INSTALLATION CAUTION / NOTICE / HINT CAUTION: Wear protective gloves. Sharp areas on the parts may injure your hands. HINT:
Use the same procedure for the RH and LH sides.
The procedure listed below is for the LH side.
PROCEDURE 1. INSTALL SEPARATE TYPE FRONT SEATBACK COVER LH HINT:
When
