Speed Signal Circuit: Procedure

1. The circuits that send vehicle speed signals to this system are inspected in the meter information. Refer to Speed Signal Circuit .
2. During inspection for the meter/gauge system, if there is an instruction that indicates to go back to inspections for the lighting system, proceed to the next step.

NEXT: Go to next step 

1. Disconnect the L27 combination meter sub-assembly connector.
2. Disconnect the A48 headlight leveling ECU assembly connector.
3. Measure the resistance according to the value(s) in the table below.

   Standard Resistance

   Tester Connection	Condition	Specified Condition
   A48-16 (SPDR) - L27-15 (+S)	Always	Below 1 Ω

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Check the output waveform.
   Fig 1: Inspecting Combination Meter Sub-Assembly With Waveform Reference

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   1. Remove the combination meter sub-assembly with the connector still connected.
   2. Connect an oscilloscope to terminal L27-15 (+S) and body ground.
   3. Turn the power switch on (IG).
   4. Check the signal waveform according to the condition(s) in the table below.

      Item	Condition
      Tool setting	5 V/DIV., 20 ms./DIV.
      Vehicle condition	Driving at approximately 20 km/h (12 mph)

      OK

      The waveform is displayed as shown in the illustration above, (Fig 1).

      TEXT IN ILLUSTRATION
      
      

      *a	Component with harness connected (Combination Meter Sub-assembly)

      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 → See step   5 

OK → See step   4