Voltage Measurement With Breakout Harness At Main Power Relay - Navistar International DT 466 Diagnostic/Troubleshooting Manual

Voltage Measurement with Breakout Harness at
Main Power Relay
NOTE: This is an alternate procedure for any of the
following:
• A 12-pin Breakout Harness is not available
• Expected voltages were not to spec, when using
the 12-pin Breakout Harness
Tools
• Relay Breakout Harness
• Digital Multimeter (DMM)
Procedure
WARNING: To avoid serious personal injury,
possible death, or damage to the engine or
vehicle, read all safety instructions in the "Safety
Information" section of this manual.
NOTE: Batteries must be fully charged before doing
the following steps.
1. Turn the ignition switch to OFF and ensure all
accessories are turned off.
Figure 209 Relay Breakout Harness
Read all safety instructions in the "Safety Information" section of this manual before doing any procedures.
5 HARD START AND NO START DIAGNOSTICS
Follow all warnings, cautions, and notes.
© August 2008 Navistar, Inc.
2. Connect Relay Breakout Harness between IDM
main power relay and power distribution center or
chassis harness depending on application.
NOTE: Depending on application, the relay could
be one of two kinds. Check power distribution
center or cab cowl.
3. Connect DMM POS lead to 87 and NEG to ground
terminal on cowl.
4. Crank engine for 20 seconds and measure
voltage.
5. Record the lowest voltage on Diagnostic Form.
• If the voltage is below 7 V, the IDM main
power relay may be resetting, resulting from
low voltage and current from the batteries
or problems in the ignition circuit or power
feed circuits. See "IDM PWR, Injector Drive
Module Power" in Section 7 (page 479).
• If the voltage is above 7 V, continue with Hard
Start and No Start tests.
NOTE: Results can be above 7 V, but there may
be a problem between the main power relay and
IDM. If a Hard Start / No Start problem remains
after all Diagnostic Form tests are complete,
check voltage at 12-pin connector and IDM
connector.
EGES-270-1
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