COVER AS-VALVE 4553839 - Caterpillar

TECHNICAL INFORMATION BULLETIN June 09, 2004
Truck Engines
C7 (KAL 16920 ? 39192)
Component Code: 4493SUBJECT: Engine Control System and Charging System Failures
PROBLEM:
Dead batteries or intermittent diagnostic event lights may indicate that an engine control system or charging system failure has occurred. The most likely cause for the dead batteries or intermittent diagnostic event lights is that an internal short condition exists in the air inlet heater relay. Part numbers that are affected are 209-5581, 223-7576, 247-4104, 213-1201, and 235-8633.
SOLUTION:
Determine if an internal short exists in the air inlet heater relay.
PROCEDURE:
1.) Note: The key switch must always be in the OFF position during this test. Do not disconnect any wires to the relay until required in the procedure below. This includes the J501/P501 relay harness connector.
2.) Using a DC voltmeter, measure the DC voltage that is present between P501 pin 1 and engine ground. If the measured voltage is greater than 0.3 volts DC then open the J501/P501 relay harness connector. If the measured DC voltage between P501 pin 1 and engine ground is now equal to 0.0 volts DC, then an internal short in the relay exists. Remove and replace the relay. See Figure 1 below for voltage measurement points.
Figure 1
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