K 2500 Truck 4WD V8-379 6.2L DSL VIN C FI (1989)
Figure 2
SERVICE PROCEDURE:
(Figure 2)
Perform all diagnostic procedures as listed in the applicable Service Manual for a specific electrical condition before checking the transmission. If no
cause can be determined, perform the test procedures in this bulletin BEFORE removing tbe bottom pan of the transmission.
Electrical Testing Vehicle for a Short to Ground
1.
Turn off ignition.
2.
Disconnect the wiring harness from the transmission at the transmission case.
3.
Replace the blown fuse.
4.
Start the truck and check if vehicle condition is still present.
If the condition is still present, the TCC wiring is probably not the cause. If the condition is not present, test the TCC solenoid wiring.
Testing for a Short to Ground In the TCC Solenoid Wiring
1.
Turn off ignition.
2.
Disconnect the wiring harness from the transmission at the transmission case.
3.
Using a 1.5 volt self powered test light or a high impedance ohmmeter (such as Kent-Moore J 34029-A), insert one probe into terminal A of the
harness connector (in the transmission case), and connect the other probe to the transmission case. Observe the test light or ohmmeter. Remove the
probe from terminal A and insert it into terminal D. Observe the test light or ohmmeter.
4.
If the test light glows or the ohmmeter reads near zero, this indicates a short to ground in either wire A or D of the TCC solenoid wiring
If a short to ground is detected in either wire, the TCC solenoid wiring must be replaced. DO NOT ATTEMPT TO REPAIR IT!
SERVICE PARTS INFORMATION:
All service stock at GMSPO has been verified good. Refer to the Electrical Diagrams in the Transmission Diagnosis section of the appropriate Service
Manual to determine which TCC solenoid wiring assembly is correct for the transmission model you are servicing.
SERVICE MANUAL REFERENCE:
Whenever replacing a TCC solenoid wiring assembly, follow all procedures as outlined in the Transmission Unit Repair section of the applicable Service
Manual. Again, diagnosis information in this bulletin is NOT contained in any Service Manual.
DIAGNOSIS INFORMATION:
