Chevrolet Silverado / GMC Sierra. Service manual — part 1023

Fig. 19: Setting Main Function Switch To FLOW Position
Courtesy of GENERAL MOTORS CORP.

1. Turn the main function switch to the FLOW position and allow the oil to flow for 15

seconds. Observe and note the flow rate. This is the TESTED flow rate.

2. Compare the TESTED flow rate to the MINIMUM flow rate information previously

recorded.

If the TESTED flow rate is equal to or greater than the MINIMUM flow rate
recorded, the oil cooling system is functioning properly. Perform Code Recording

IMPORTANT: If the flow rate is less than 0.5 gpm, the LCD displays an

error message. Refer to the Troubleshooting section of the
tester operation manual.

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E/4L70-E - Cab & Chassis Sierra, Cab & Chassis

Silverado, Sierra & Silverado

Procedure.

If the TESTED flow rate is less than the MINIMUM flow rate previously recorded,
repeat the back flush and forward flush procedures.

3. If the TESTED flow rate is less than the MINIMUM flow rate after the second test, perform

the Code Recording Procedure.

1. Replace the transmission oil cooler.

2. Connect the supply and waste hoses to the cooler lines in the normal flow direction.

Perform the Flow Test.

3. Perform the Code Recording Procedure.

CODE RECORDING PROCEDURE

Fig. 20: Setting Main Function Switch To CODE Position
Courtesy of GENERAL MOTORS CORP.

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E/4L70-E - Cab & Chassis Sierra, Cab & Chassis

Silverado, Sierra & Silverado

1. Turn the main function switch to the CODE position.

2. Record TESTED flow rate, temperature, cycle and seven-character flow code information

on the repair order.

CLEAN-UP

IMPORTANT:

If power is interrupted prior to the recording of the 7-
character code, the code will be lost and the flow rate
test will need to be repeated.

The flow test must run for a minimum of 8-10 seconds
and be above 0.5 gpm for a code to be generated.

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E/4L70-E - Cab & Chassis Sierra, Cab & Chassis

Silverado, Sierra & Silverado

Fig. 21: View Of Main Power Switch & Main Function Switch
Courtesy of GENERAL MOTORS CORP.

1. Turn the main function switch to the IDLE position and allow the supply vessel pressure to

dissipate.

2. Turn the main power switch to the OFF position.

IMPORTANT: A small amount of water may drain from the bottom of the

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E/4L70-E - Cab & Chassis Sierra, Cab & Chassis

Silverado, Sierra & Silverado