Isuzu 20LE - Diagnostic Aids

6E1-60 DRIVEABILITY AND EMISSIONS
• Thermo switch (FRT) is OFF.
• Pressure switch is OFF.
• Ignition switch is OFF.
Diagnostic Aids
To diagnose an intermittent fault, check for the
following conditions:
• Poor connection at the ECM-Inspect harness
connections for backed-out terminals, improper
mating, broken locks, improperly formed or
damaged terminals, and poor terminal-to-wire
connection.
• Damaged harness-Inspect the wiring harness for
damage; shorts to Ground, shorts to Battery
Voltage, and Open circuits. If the harness appears
to be OK, observe the A/C clutch while moving
connectors and wiring harnesses related to the A/C.
A sudden clutch malfunction will indicate the source
of the intermittent fault.
A/C Clutch Diagnosis
This chart should be used for diagnosing the electrical
portion of the A/C compressor clutch circuit. A Scan
Tool will be used in diagnosing the system. The Scan
Tool has the ability to read the A/C request input to the
ECM. The Scan Tool can display when the ECM has
commanded the A/C clutch ON. The Scan Tool should
have the ability to override the A/C request signal and
energize the A/C compressor relay.
A/C Clutch Control Circuit Diagnosis
Step Action Value(s) Yes No
1
Was the “On-Board Diagnostic (OBD) System Check”
performed? - Go to Step 2 Go to OBD
System Check
2
1. Ignition ON, Engine OFF.
2. Review and record the customer complaint.
3. Operate the vehicle within the costomer complaint
conditions as noted.
4. Using the Scan Tool, monitor “DTC” info for DTC 87 or
88.
-
Refer to
Diagnostic Aids
Go to step 3
3
1. Ignition OFF.
2. Remove the A/C Compressor Clutch Relay from the
Underhood Electrical Center.
3. Ignition ON, Engine OFF.
4. Using a Digital Voltmeter (DVM), check for voltage on
the Fused pins of the A/C Compressor Clutch Relay
connector.
Does the DVM read the following value?
12 Volts Go to Step 5 Go to Step 4
4
Check the suspect circuit(s) between the A/C Compressor
Clutch Relay connector and the Fuse for the following
conditions:
• A short to ground
• An open circuit
• A short to voltage
Was the problem found?
- Verify Repair -