Date: JULY, 1988
Subject: INTERMITTENT NO-START CONDITION CAUSED BY THE VEHICLE ANTI-THEFT SYSTEM (VATS)
Model and Year: 1986-88 CORVETTE
TO: ALL CHEVROLET DEALERS
Chevrolet Dealer Service Bulletin 87-140 (Section 8A) dated May, 1987 is being revised to
provide additional diagnostic steps plus a new lock cylinder part number. All copies of
Bulletin 87-140 should be discarded.
Some 1986-88 Corvettes have been returned because of an intermittent no-start
condition. In some cases the vehicle may start after waiting for approximately 4 minutes.
This condition could be caused by a damaged ignition lock cylinder or damaged resistor
pellet inside the ignition key. This causes the VATS module to sense an intermittent
resistance value or open circuit at the pellet, which then shuts the system down for
approximately 4 minutes. (Refer to the 1988 Corvette Electrical Diagnosis service Manual
Supplement, pages 8A-133-8 through 8A-133-14 for a more detailed description of the
If a vehicle is returned to the dealership with an intermittent no start condition
caused by VATS, the following items can be checked in addition to the diagnostics in the
Corvette Electrical Diagnosis Service Manual Supplement.
- The braided ground strap connected between the left hand rear of the engine and the
frame next to the battery should be fastened tightly. Lack of a good
ground for VATS could cause an intermittent no start.
- The resistor pellet in the ignition key should be visually checked to see if there is
any foreign material (plastic flash, dirt, etc.) covering either side of the metal
contact. If foreign material is present, carefully remove or clean the material away from
the pellet contact.
- The metal contacts inside the ignition lock cylinder (located in the steering column)
should be clean and parallel to each other. If these contacts are bent or damaged, they
will not make a good contact with the pellet in the key resulting in a no-start condition.
If the contacts are damaged, replace the ignition lock cylinder with a new replacement
lock cylinder, P/N 26009609, which is available from GMSPO.
NOTICE WHEN A LOCK CYLINDER IS REPLACED THERE IS NO NEED TO ALSO REPLACE THE VATS MODULE.
- If a vehicle has a history of intermittent no starts and repeated diagnosis can not
repair the vehicle, the ignition lock cylinder should be replaced with a new lock
cylinder, P/N 26009609.
Parts are currently available from GMSPO.
New keys (3) of the proper code should be ordered when replacing the lock cylinder.
Check the old key to obtain the proper code, using the (J35628) VATS Interrogator. All key
codes (#1-#15) are available from GMSPO and can be used.