TOYOTA

REPAIR MANUAL FOR CHASSIS & BODY

TOYOTASUPRA


Circuit Diagram is available here (79kb)

Diagnosis System

OUTPUT OF DIAGNOSTIC CODES

1. Indicate Type A Code

  1. Turn the ignition switch on.
  2. Push the set/coast switch on, and keep it on.
  3. Push the main switch on.
  4. Meet the conditions listed below
  5. Read the diagnosis code on the main switch indicator
NoCondition Indication CodeDiagnosis
1Set/Coast switch on Set/Coast switch circuit is normal
2Accel/Resume switch on Accel/Resume switch circuit is normal
3Vacuum switch on Vacuum switch circuit is normal
4Each cancel switch on
(Stop light switch, Parking brake switch,
Clutch switch, Neutral start switch,
Cancel switch)
Each cancel switch circuit is normal
5Drive 40km/h (25mph) or over Speed sensor circuit is normal
6Drive 40 km/h (25 mph) or below Speed sensor circuit is normal
NOTE:

2. Indicate Type B Code

  1. Do not turn the ignition switch and main switch off.
  2. Push the set/coast switch on three times within two seconds.
  3. Read the diagnosis code on the main switch indicator
NoIndication CodeDiagnosis
1Actuator circuit is normal
2Actuator circuit is abnormal
3Speed sensor signal circuit is abnormal
4Speed sensor signal circuit is abnormal
5Accel/resume switch circuit is abnormal
NOTE:

+------------------------+
|Turn ignition switch on.|
+----------+-------------+
           |
           |
+----------+-----------+        +--------------------+        +-----------------------------------+
|Is ECU-IG fuse normal?|-->NO-->|  Replace fuse,     |-->NO-->|* Short circuit in wire harness and|
+----------+-----------+        |Is operation normal?|        |  terminal 2 of the main switch    |
           |                    +---------+----------+        |* Inspect main switch              |
           |                              |                   +-----------------------------------+
           |                             Yes
          Yes                             |
           |                        +-----+-----+
           |                        |Fuse Faulty|
           |                        +-----------+
MAIN S/W   |
           |
+----------+--------------------------------+        +------------------------------------------+
|INSPECT POWER SOURCE                       |        |* Open circuit in wire harness between    |
|Is there battery voltage between terminal 2|-->NO-->|  ECU-IG fuse and terminal 2 of main      |
|and body ground?                           |        |  switch                                  |
+----------+--------------------------------+        +------------------------------------------+
           |
          Yes
           |
+----------+--------------------------------+        +------------------------------------------+
|INSPECT GROUND CONNECTION                  |        |* Open circuit in wire harness between    |
|Is there continuity between terminal 3 and |-->NO-->|  terminal 3 of switch and body ground    |
|body ground?                               |        |* Body ground faulty                      |
+----------+--------------------------------+        +------------------------------------------+
           |
          Yes
           |
+----------+--------------------------------+        +------------------------------------------+
|INSPECT SWITCH OPERATION                   |        |* Short circuit in wire harness between   |
|Is there battery voltage between terminal 6|-->NO-->|  Term 6 of switch and term 10 of computer|
|and body ground with main switch turned on?|        |* Inspect main switch                     |
+----------+--------------------------------+        +------------------------------------------+
           |
          Yes
           |
+----------+--------------------------------+        +------------------------------------------+
|INSPECT INDICATOR LIGHT OPERATION          |        |* Inspect main switch                     |
|Connect Terminal 4 to body ground.         |-->NO-->|                                          |
|Does indicator light with main switch on?  |        |                                          |
+----------+--------------------------------+        +------------------------------------------+
           |
          Yes
CONTROL SW |
+----------+--------------------------------+        +------------------------------------------+
|INSPECT GROUND CONNECTION                  |        |* Open circuit in wire harness between    |
|Is there continuity between terminal 2 and |-->NO-->|  terminal 2 and body ground              |
|body ground                                |        |* Body ground faulty                      |
+----------+--------------------------------+        +------------------------------------------+
           |
          Yes
           |
+----------+--------------------------------+        +------------------------------------------+
|INSPECT SET/COAST SWITCH OPERATION         |        |* Inspect control switch                  |
|Is there continuity between terminal 3 and |-->NO-->|                                          |
|body ground with set/coast switch on?      |        |                                          |
+----------+--------------------------------+        +------------------------------------------+
           |
          Yes
           |
+----------+--------------------------------+        +-------------------------------------------+
|INSPECT SET/COAST SWITCH OPERATION         |        |* Short Circuit in wire harness between    |
|Is there continuity between terminal 3 and |-->YES->|  terminal 3 of control switch and terminal|
|body ground with set/coast switch off?     |        |  17 of computer                           |
+----------+--------------------------------+        +-------------------------------------------+
           |
          No
COMPUTER   |
+----------+--------------------------------+
|Disconnect connector from computer and     |
|inspect connector on wire harness side as  |
|follows                                    |
+----------+--------------------------------+
           |
           |
           |
+----------+--------------------------------+        +-------------------------------------------+
|INSPECT POWER SOURCE                       |        |* Open circuit in wire harness between     |
|Is there battery voltage between term 10   |-->NO-->|  terminal 10 of computer and terminal 6   |
|and body ground with main switch turned on?|        |  of main switch                           |
+----------+--------------------------------+        +-------------------------------------------+
           |
          Yes
           |
+----------+--------------------------------+        +-------------------------------------------+
|INSPECT GROUND CONNECTION                  |        |* Open circuit in wire harness between     |
|Is there continuity between terminal 13 and|-->NO-->|  terminal 13 and body ground              |
|body ground?                               |        |* Body ground faulty                       |
+----------+--------------------------------+        +-------------------------------------------+
           |
          Yes
           |
+----------+--------------------------------+        +-------------------------------------------+
|INSPECT INDICATOR LIGHT CIRCUIT            |        |* Open circuit in wire harness between     |
|Connact terminal 3 to body ground          |-->NO-->|  terminal 3 of computer and terminal 4 of |
|Does indicator light with main switch on?  |        |  main switch                              |
+----------+--------------------------------+        +-------------------------------------------+
           |
          Yes
           |
+----------+--------------------------------+        +-------------------------------------------+
|INSPECT SET/COAST SWITCH CIRCUIT           |        |* Open circuit in wire harness between     |
|Is there continuity between terminal 17 and|-->NO-->|  terminal 17 of computer and terminal 3 of|
|body ground with set/coast switch on?      |        |  control switch                           |
+----------+--------------------------------+        +-------------------------------------------+
           |
          Yes
           |
+----------+--------------------------------+        
|Replace Computer!                          |
+----------+--------------------------------+        

MA70 series Jan 1986 (Pub No. RM027E) pg BE-67-72