Air Conditioning Signal
This signals the ECM when there is a demand for cooling from the air conditioning system.
Inspection of Air Conditioning
Signal.
ECM CONNECTORS
Check for a short in the circuit:
1. Turn the ignition switch OFF.
2. Disconnect the 12P connector
from the cooling fan control
unit.
3. Turn the ignition switch ON (II).
4. Measure voltage between ECM
connector terminals C2 and
A26.
WIRE SIDE OF FEMALE TERMINALS
Is there approx. 10 V?
Check for a short in the wire:
1. Turn the ignition switch OFF.
2. Disconnect the ECM connec-
tor C (12P) from the ECM.
3. Check for continuity between
ECM connector terminal C2
and body ground.
Is there continuity?
— Repair short in the wire
between the ECM (C2) and the
cooling fan control unit.
— See the air conditioner inspec-
tion (see section 22).
Substitute a known-good ECM
and recheck. If prescribed volt-
age is now available, replace
the original ECM.
See the air conditioner inspec-
tion (see section 22).
Check for an open in the circuit:
1. Turn the ignition switch OFF.
2. Reconnect the 12P connector to
the cooling fan control unit.
3. Turn the ignition switch ON (II).
4. Momentarily connect ECM
connector terminals A8 to
A26 several times with a
jumper wire.
(To page 11-118)
Idle Control System
Air Conditioning Signal
(From page 11-117)
Is there a clicking noise from the
A/C compressor clutch?
Check for the operation of the
A/C:
1. Start the engine.
2. Turn the blower switch ON.
3. Turn the A/C switch ON.
Does the A/C operate?
Air conditioning signal is OK.
A/C CLUTCH RELAY 4P CONNECTOR
Check for an open in the wire:
Momentarily connect the No. 4 ter-
minal of the 4P connector on the
A/C clutch relay to body ground
several times.
WIRE SIDE OF
FEMALE TERMINALS
Is there a clicking noise from the
A/C compressor clutch?
See air conditioner inspection (see
section 22).
Repair open in the wire between
the ECM (AS) and the A/C clutch
relay.
ECM CONNECTORS
Check for an open in the wire:
Measure voltage between ECM
connector terminals C2 and A26.
WIRE SIDE OF FEMALE TERMINALS
Is voltage less than 1.0 V? Repair open in the wire betweenthe ECM (C2) and the A/C switch.
Substitute a known-good ECM
and recheck. If symptom/indi-
cation goes away, replace the
original ECM.
See the air conditioner inspec-
tion (see section 22).