Toyota Camry (XV70): 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 following diagram 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(s) still connected.
(2) Connect an oscilloscope to terminal K21-6 (+S) and body ground.
(3) Turn the engine switch on (IG). (4) Turn a wheel slowly.
(5) Check the signal waveform according to the condition(s) in the table below.
Item | Condition |
Measurement terminal |
K21-6 (+S) - Body ground |
Tool setting | 5 V/DIV., 20 ms./DIV. |
Vehicle condition |
Wheel being rotated | 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. |
|
*a | Component with harness connected
(Combination Meter Assembly) | | |
OK |
| |
2. |
CHECK HARNESS AND CONNECTOR (NAVIGATION ECU - COMBINATION METER ASSEMBLY) |
(a) Disconnect the K17 navigation ECU connector.
(b) Disconnect the K21 combination meter assembly connector.
(c) Measure the resistance according to the value(s) in the table below.
Standard Resistance:
Tester Connection | Condition |
Specified Condition |
K17-9 (SPD) - K21-6 (+S) |
Always | Below 1 Ω |
NG |
| REPAIR OR REPLACE HARNESS OR CONNECTOR |
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HINT:
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PROCEDURE
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PROCEDURE
1.
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LATCH anchors are provided
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(Marks displaying the location
of the anchors are attached to
the seats.)
■ When installing in the rear outboard seats
Install the child restraint system in accordance to the operation
manual encl