DTC P0608. GMC Truck Savana

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 2004 🢒 Savana - AWD 🢒 Engine 🢒 Engine Controls - 4.8L, 5.3L, and 6.0L 🢒 DTC P0608

DTC P0608 With Throttle Actuator Control

Circuit Description

The powertrain control module (PCM) creates the vehicle speed signal by pulsing the signal circuit to ground. The PCM pulses the circuit at the same rate as the vehicle speed signal input. The PCM monitors the voltage on the vehicle speed signal circuit. If the PCM determines the voltage is out of the normal operating range, a DTC sets.

Conditions for Running the DTC

•	The engine speed is greater than 400 RPM.

•	The ignition voltage is between 9-16 volts.

Conditions for Setting the DTC

•	The PCM detects that the commanded state of the driver and the actual state of the control circuit do not match.

•	The condition must be present for a minimum of 5 seconds.

Action Taken When the DTC Sets

•	The cruise control system is disabled.

•	The PCM stores a DTC P0608 in memory.

•	The PCM records the operating conditions at the time the DTC sets. The PCM displays the failure information in the Failure Records on the scan tool.

Conditions for Clearing the DTC

•	The history DTC clears after 40 malfunction free warm-up cycles.

•	The DTC becomes history when the conditions for setting the DTC are no longer present.

•	The PCM receives the clear code command from the scan tool.

Diagnostic Aids

•	If any additional powertrain DTCs are stored, refer to Diagnostic Trouble Code (DTC) List in Engine Controls - 4.8L, 5.3L, and 6.0L.

•	For intermittent diagnosis, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Step	Action	Value(s)	Yes	No
Schematic Reference: Cruise Control Schematics Connector End View Reference: Cruise Control Connector End Views or Engine Controls Connector End Views in Engine Controls - 4.8L, 5.3L, and 6.0L
1	Did you perform the Cruise Control Diagnostic System Check?	--	Go to Step 2	Go to Diagnostic System Check - Cruise Control
2	Turn the ignition OFF. Install a scan tool. Raise the vehicle drive wheels. Refer to Lifting and Jacking the Vehicle in General Information. Start the engine. Place the transmission into drive. With a scan tool, observe the Vehicle Speed Sensor parameter in the PCM Cruise Control Data data list. Does the Vehicle Speed Sensor parameter indicate any vehicle speed?	--	Go to Step 4	Go to Step 3
3	Is DTC P0502 or P0503 current in the powertrain control module (PCM)?	--	Go to Diagnostic Aids	Go to Step 7
4	Turn the ignition OFF. Disconnect the throttle actuator control (TAC) module. Turn the ignition ON, with the engine OFF. Measure the voltage from the vehicle speed signal circuit to a good ground. Does the voltage measure greater than the specified value?	8.5 V	Go to Step 5	Go to Step 6
5	Test the vehicle speed signal circuit for a short to voltage. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition?	--	Go to Step 11	Go to Step 8
6	Test the vehicle speed signal circuit for a short to ground. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you find and correct the condition?	--	Go to Step 11	Go to Step 7
7	Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition?	--	Go to Step 11	Go to Step 9
8	Inspect for poor connections at the harness connector of the TAC module. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition?	--	Go to Step 11	Go to Step 10
9	Important:: Program the replacement PCM. Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls - 4.8L, 5.3L, and 6.0L. Did you complete the replacement?	--	Go to Step 11	--
10	Replace the TAC module. Refer to Electronic Throttle Actuator Control Module Replacement in Engine Controls - 4.8L, 5.3L, and 6.0L. Did you complete the replacement?	--	Go to Step 11	--
11	Use the scan tool in order to clear the DTCs. Operate the vehicle within the Conditions for Running the DTC. Does the DTC reset?	--	Go to Step 2	System OK

DTC P0608 Without Throttle Actuator Control

Circuit Description

Conditions for Running the DTC

•	The engine speed is greater than 400 RPM.

•	The ignition voltage is between 9-18 volts.

Conditions for Setting the DTC

•	The PCM detects that the commanded state of the driver and the actual state of the control circuit do not match.

•	The condition must be present for a minimum of 5 seconds.

Action Taken When the DTC Sets

•	The PCM stores a DTC P0608 in memory.

•	The PCM records the operating conditions at the time the DTC sets. The PCM displays the failure information in the Failure Records on the scan tool.

Conditions for Clearing the DTC

•	The history DTC clears after 40 malfunction free warm-up cycles.

•	The DTC becomes history when the conditions for setting the DTC are no longer present.

•	The PCM receives the clear code command from the scan tool.

Diagnostic Aids

•	If any additional powertrain DTCs are stored, refer to:

•	Diagnostic Trouble Code (DTC) List in Engine Controls - 4.3L.

•	Diagnostic Trouble Code (DTC) List in Engine Controls - 4.8L, 5.3L, and 6.0L.

•	For intermittent diagnosis, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.

Step

Action

Value(s)

Yes

Schematic Reference: Instrument Cluster Schematics in Instrument Panel, Gages, and Console

Connector End View Reference: Cruise Control Connector End Views

Did you perform the Cruise Control Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Cruise Control

Turn the ignition OFF.
Install a scan tool.
Raise the vehicle drive wheels. Refer to Lifting and Jacking the Vehicle in General Information.
Start the engine.
Place the transmission into drive.
With a scan tool, observe the Vehicle Speed Sensor parameter in the PCM Engine Data 1 data list.

Does the Vehicle Speed Sensor parameter indicate any vehicle speed?

Go to Step 4

Go to Step 3

Is DTC P0502 or P0503 current in the powertrain control module (PCM)?

Go to Diagnostic Aids

Go to Step 7

Turn the ignition OFF.
Disconnect C2 at the PCM.
Turn the ignition ON, with the engine OFF.
Measure the voltage from the vehicle speed signal circuit to a good ground.

Does the voltage measure greater than the specified value?

8.5 V

Go to Step 5

Go to Step 6

Test the vehicle speed signal circuit for a short to voltage. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 11

Go to Step 7

Test the vehicle speed signal circuit for a short to ground. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 11

Go to Step 8

Inspect for poor connections at the harness connector of the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 11

Go to Step 9

Inspect for poor connections at the harness connector of the cruise control module. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

Go to Step 11

Go to Step 10

Important:: Program the replacement PCM.

Replace the PCM. Refer to:

•	Powertrain Control Module Replacement in Engine Controls - 4.3L

•	Powertrain Control Module Replacement in Engine Controls - 4.8L, 5.3L, and 6.0L

Did you complete the replacement?

Go to Step 11

Replace the cruise control module. Refer to Cruise Control Module Replacement .

Did you complete the replacement?

Go to Step 11

Use the scan tool in order to clear the DTCs.
Operate the vehicle within the Conditions for Running the DTC.

Does the DTC reset?

Go to Step 2

System OK