Engine - Intermittent No-Start Hot or Cold

88chevy02
GMC NUMBER: 88-T-73

GROUP: 6D - Engine Electrical

DATE: January, 1988

CORPORATE
NUMBER: 849101

SUBJECT: INTERMITTENT NO-START ON HOT OR COLD ENGINE

MODELS: 1988 C/K TRUCKS EQUIPPED WITH LB4 4.3L ENGINES (ENGINE VIN CODE Z)

FIGURE 1:

Some 1988 C/K trucks equipped with LB4 4.3L engines may experience an intermittent no-start condition on hot or cold engines when equipped with part number 9000719 (OE) or 10465001 (service) starting motors having the following date codes stamped into the starting motor Commutator End frame (see Figure No. 1).

Date Code Range 7F15 thru 7F30 7G01 thru 7G31 7H01 thru 7H27

This starting motor date code is visible to the technician without removing the starting motor from the vehicle.

Condition: Some vehicles listed above may not start at times because the starter will not stay engaged and crank the engine. This condition may first occur when the engine is extremely hot or cold, and will be characterized by a chattering or oscillating sound from the starting motor. Eventually, the starter may not crank the engine even at mid-range temperatures.

Cause: The inability of the starter to stay engaged and crank the engine may be caused by an intermittent ground connection to the solenoid hold-in coil. The intermittent ground

condition is due to a temporary processing change made in solenoid manufacture and is limited to some, but not all, starting motors with the above part numbers and date codes. This connection is internal to the solenoid and cannot be checked visually. Because of the intermittent nature, an electrical check of the hold-in circuit is not always reliable. This condition must not be confused with a similar condition which may be caused by a discharged battery or a poor electrical connection in the cranking circuit.


Correction: If a customer comments on the starting motor not staying engaged to crank a hot or cold engine, the diagnostic procedure described in Service Manual X-8731, Page 6D- 26, should be used. Check the battery to see that it is in a sufficient state of charge, and check the wiring connections to the battery, starting motor, solenoid, and ignition switch to assure that they are clean and tight. If these checks do not reveal any other condition that may have caused the comment, the starting motor date code should be checked to see if it falls within the date code range listed above. If it does, the starting motor should be replaced.

For repairs to vehicles under warranty, use Labor Op J4640, Labor Time 0.5 hr.