If the connector is clogged with mud or dust, blow it off with compressed air.
If the terminals of the main harness connectors are damaged, replace the main harness.
If the terminals of the ECU connectors are damaged, replace the ECU.

Gray Connector [A]

Special Tool - Hand Tester: 57001-1394
ECU Grounding Inspection
Connections:
(I) BK/Y leads (ECU terminal 40, 73 or 74) ←→ Battery (–) Terminal
(II) Engine Ground ←→ Battery (–) Terminal
Criteria: Both: 0 Ω
If no continuity, check the connectors, the engine ground lead, or main harness, and repair or replace them if necessary.
If the wiring is good, check the power source voltage of the ECU.

NOTE
Be sure the battery is fully charged.
Special Tool - Needle Adapter Set: 57001-1457
ECU Power Supply Inspection Connections:
(I) Digital Meter (+) → Terminal 41 (W/BK)
Digital Meter (–) → Battery (–) terminal
(II) Digital Meter (+) → Terminal 53 (BR/W)
Digital Meter (–) → Battery (–) terminal
(III) Digital Meter (+) → Terminal 54 (W/BK)
Digital Meter (–) → Battery (–) terminal
Ignition Switch OFF:
Terminal 41 (W/BK): Battery Voltage
Terminal 53 (BR/W): 0 V
Terminal 54 (W/BK): Battery Voltage
Ignition Switch ON:
All: Battery Voltage
If the reading is out of the specification, check the following.
Main Fuse 30 A (see Fuse Inspection in the Electrical System chapter)
ECU Fuse 15 A (see Fuse Inspection in the Electrical System chapter)
ECU Main Relay (see Relay Circuit Inspection in the Electrical System chapter)
Power Source Wiring (see wiring diagram in this section)
If the fuse, wiring and relay are good, replace the ECU (see ECU Removal/Installation).
ECU Removal
ECU Power Source CircuitOil Pressure Relief Valve Inspection
Remove the oil pressure relief valve (see Oil Pressure
Relief Valve Removal).
Check to see if the valve [A] slides smoothly when pushing
it in with a wooden or other soft rod, and see if it comes
back to its seat by spring [B] pressure.
NOTE
Inspect the valve in its assembled stat ...
Intake Air Pressure Sensor #1 Installation
NOTE
The intake air pressure sensor #1 is the same part as
the intake air pressure sensor #2.
Installation is basically the reverse of removal.
Position the intake air pressure sensor #1 [A] between the
projections [B] on the rubber damper.
Install the rubber damper [A] on the bracket ...
Camshaft Runout Inspection
Remove the camshafts (see Camshaft Removal).
Set the camshaft in a camshaft alignment jig or on V
blocks.
Measure the runout with a dial gauge at the specified
place as shown in the figure.
If the runout exceeds the service limit, replace the
camshaft.
Camshaft Runout
Standard: TIR ...