DTC P1644 Traction Control Delivered Torque Output Circuit. Chevrolet Corvette 1997

For 1990-2009 cars only

Makes 🢒 Chevrolet 🢒 1997 🢒 Corvette 🢒 DTC 🢒 DTC P1644 Traction Control Delivered Torque Output Circuit

Engine Controls Components
Cell 20: CKP, CMP, KS and Traction Control System
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

Circuit Description

The Electronic Brake and Traction Control Module (EBTCM) supplies 12.0 Volts on the Delivered Torque circuit to the PCM. The PCM toggles this 12.0 volt signal to a ground in order to produce a duty cycle signal. The signal is proportional to the amount of engine output torque reduction . In order to reduce engine output torque, the PCM reduces the amount of spark advance and in some cases the PCM disables a number of fuel injectors. This diagnostic test checks for a Delivered Torque signal failure. If the PCM does not receive the Delivered torque signal, this DTC sets.

Conditions for Setting the DTC

•	The traction control has not failed.

•	The engine speed is greater than 500 RPM for 20 seconds.

•	The PCM does not receive the Delivered torque signal for 3 seconds.

Action Taken When the DTC Sets

•	The powertrain control module (PCM) stores the DTC information into memory when the diagnostic runs and fails.

•	The malfunction indicator lamp (MIL) will not illuminate.

•	The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records.

Conditions for Clearing the MIL/DTC

•	A last test failed, or the current DTC, clears when the diagnostic runs and does not fail.

•	A history DTC clears after 40 consecutive warm-up cycles, if failures are not reported by this or any other emission related diagnostic.

•	Use a scan tool in order to clear the MIL/DTC.

Diagnostic Aids

The following may cause an intermittent:

•	Mis-routed harness

•	Rubbed through wire insulation

•	Broken wire inside the insulation

Test Description

The numbers below refer to the step numbers on the diagnostic table.

This step determines if the PCM is receiving the 12.0 volts from the EBTCM.

This DTC will not report a pass. The scan tool status for this DTC will never report a pass. The scan tool will only display when the diagnostic fails. The repair is not complete if the scan tool indicates that the diagnostic ran and failed.

Step

Action

Value(s)

Yes

Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

Important:

•	Perform this diagnostic procedure only if the customer's concern is related to the ABS and/or the Traction Control system(s). Refer to ABS Diagnostic System Check for further diagnosis.

•	Verify communication between the scan tool and the EBTCM before you continue with this diagnostic. Refer to ABS Diagnostic System Check if you can not establish communications.

Turn OFF the ignition.
Install a scan tool.
Turn ON the ignition leaving the engine OFF.

Are any ABS/Traction Control and/or BCM DTCs set?

Go to applicable DTC

Go to Step 3

Disconnect the PCM connector located on the same side as the manufacturer's logo. Refer to Powertrain Control Module/Throttle Actuator Control Module Replacement .
Turn ON the ignition leaving the engine OFF.
Probe the Delivered Torque circuit at the PCM electrical connector using the J 35616-A connector kit.
Connect the DMM J 39200 to the Delivered Torque circuit and ground.

Does the DMM display near the specified value?

B+

Go to Step 4

Go to Brakes

Check the terminal connections at the PCM.
If you find a connection problem, repair/replace the terminal as necessary. Refer to Body and Accessories/Wiring Systems.

Did you find and correct the condition?

Go to Step 6

Go to Step 5

Important:: Program the replacement PCM. Refer to Powertrain Control Module/Throttle Actuator Control Module Replacement .

Replace the PCM.

Is the action complete?

Go to Step 6

Select the Diagnostic Trouble Code (DTC) option and the Clear DTC Information option using the scan tool.
Start engine and idle at normal operating temperature.
Select the Diagnostic Trouble Code (DTC) option and the Specific DTC option, then enter the DTC number using the scan tool.
Operate the vehicle within the Conditions for Setting the DTC as specified in the supporting text, if applicable.

Does the scan tool indicate that this test failed?

Go to Step 2

Go to Step 7

Select the Capture Info option and the Review Info option using the scan tool.

Does the scan tool display any DTCs that you have not diagnosed?

Go to applicable DTC

System OK