K 2500 Truck 4WD V8-379 6.2L DSL VIN C FI (1989)
Radio/Stereo: All Technical Service Bulletins
Tools - Radio Diagnostics
Group Ref.: 9 - Accessories
Bulletin No.: 469601
Date: August, 1994
INFORMATION
SUBJECT:
RADIO DIAGNOSTICS - KENT-MOORE TOOL J 39788
MODELS:
1968-92 CHEVROLET AND GMC TRUCK C/K MODELS
1990-94 CHEVROLET AND GMC TRUCK TOPKICK/KODIAK MODELS
In order to further facilitate radio repairs at dealerships, Kent-Moore has released a new diagnostic adapter J 39788. This adapter will enable the
technician to properly diagnose radio system problems on all of the above mentioned vehicles using a Tech 1 scanner or a T100 terminal. The use of this
adapter cuts 0.3 hour off the time it takes to install the permanent diagnostic jumper wire described in Bulletin 268101 (Chevrolet No. 92-139-9A, GMC
Truck No. 92-9A-65, and GM of Canada No. 92-8-142).
For the 1993 model year the serial data line between the radio control box and ALDL terminal J was made part of the vehicle wiring harness on C/K
light duty trucks. For 1992 and prior C/K models J 39788 will be required or a permanent jumper wire will need to be installed to run diagnostics. This is
also true for all 1994 and prior Topkick/Kodiak medium duty trucks.
J 39788 is a simple piece of hardware that consists of a couple of lengths of wire with connectors that are hooked to a blank ALDL. This adapter is
stored in the technician's tool box between uses.
When a technician wants to run diagnostics on a vehicle, he plugs the white wire into the unused pin seven on the bottom of the radio receiver near the
six way connector at location C247 (Reference Bulletin 268101). The black wire on the tool goes to ALDL pin A ground. The Tech 1 or T100 then
plugs into the ALDL connection on the adapter. This saves the technician the trouble of making up and installing a permanent jumper wire that is
ultimately left with the vehicle and gives him a simple tool that he can reuse on the next job.
Radio system diagnosis with Tech 1 requires the Mass Storage Cartridge or Body Cartridge TK03040B. T100 requires the use of ALDL E&C adapter
part number 56746.
On these vehicles the radio system is made up of a radio control head, radio receiver, cassette deck, and on light duty trucks, a graphic equalizer. The
Tech 1 or T100 becomes a component on the data line. It allows you to monitor messages transmitted from any other component and allows you to
transmit your own messages. In addition, the Tech 1 or T100 can simulate components, allowing for the testing and diagnosis of only one component in
the system without the need for the others.
This allows the technician to test the tuner, balance controls, volume, fade, individual speakers, clock, station select and many other features. He can then
more accurately isolate the problem rather than pulling all of the separate units and sending them all off for repair. Cassette tape player functions cannot
be diagnosed with this system.
J 39788 Radio Diagnostic Adapter is available from Kent-Moore Tool Division by calling 1-800-345-2233 or Fax 1-800-578-7375.
