Service manual

G420F(FE) Service Manual 254 Chapter 8. Basic Troubleshooting
● Check Short Circuit
1. Test Method for Short to Ground Circuit
• Continuity Check with Chassis Ground
If short to ground circuit occurs as shown in [FIG.5],
the broken point can be found by performing below
Step 2 (Continuity Check Method with Chassis
Ground) as shown below.
2. Continuity Check Method (with Chassis Ground)
NOTE: Lightly shake the wire harness above and
below, or from side to side when measuring the
resistance.
Specification (Resistance)
1Ω or less → Short to Ground Circuit
1㏁ or Higher → Normal Circuit
a. Disconnect connectors (A), (C) and measure
for resistance between connector (A) and
Chassis Ground as shown in [FIG.6].
The measured resistance of line 1 and 2 in this
example is below 1Ω and higher than 1㏁
respectively. Specifically the short to ground circuit
is line 1 (Line 2is normal). To find exact broken point,
check the sub line of line1 as described in the
following step.
b. Disconnect connector (B), and measure the
resistance between connector (A) and chassis
ground, and between (B1) and chassis ground
as shown in [FIG.7].
The measured resistance between connector (B1)
and chassis groundis1Ω or less. The short to
ground circuit is between terminal 1 of connector (C)
and terminal 1 of connector (B1).