DTC P1644 Traction Control Delivered Torque Output Circuit. Cadillac Concours 1996

For 1990-2009 cars
Engine Controls Components
EBTCM/ Generator/ A/C Relay/ RSS
OBD II Symbol Description Notice
ESD Notice
ESD Notice

### Circuit Description

The PCM contains chips called Output Driver Modules that provide 7 switchable ground outputs for operating solenoids, relays, telltales, and other devices. Each of these ground outputs has an internal fault line that feeds back to the PCMs microprocessor. When the output is OFF, the output driver should receive the 12 volts fed to the solenoid, relay, etc. When the output is ON, it should receive 0 volt since it is grounding the output. If it receives 0 volt when the output is OFF or 12 volts when the output is ON, it sets the fault line low. DTC P1644 is used to monitor the fault line of the delivered torque output to the EBTCM. The EBTCM sends ignition voltage on CKT 464 to the PCM, the PCM will then rapidly pulse CKT 464 to ground creating a Pulse Width Modulated signal that indicates the percentage of torque output the engine is producing. The EBTCM uses this PWM signal for traction control.

### Conditions for Setting the DTC

#### Test Conditions

• | Brakes not applied.

• | PCM in Closed Loop fuel control.

#### Failure Condition

Fault line is low for 2.5 seconds.

### Action Taken When the DTC Sets

• | The Malfunction Indicator Lamp (MIL) will not illuminate.

• | No message will be displayed.

### Conditions for Clearing the DTC

• | A History DTC will clear after forty consecutive warm-up cycles with no failures of any non-emission related diagnostic test.

• | A Last Test Failed (current) DTC will clear when the diagnostic runs and does not fail.

• | Use a scan tool to clear DTCs.

• | Interrupting PCM battery voltage may or may not clear DTCs. This practice is not recommended. Refer to Clearing Diagnostic Trouble Codes in PCM Description and Operation.

### Diagnostic Aids

Check for an intermittent poor connection at both the PCM and the EBTCM or an open or short in CKT 464.

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Go to A Powertrain On Board Diagnostic (OBD) System Check

2

1. Turn the key ON.
2. Using a scan tool select Delivered Torque Driver display.
3. Review the Failure Records data and operate the vehicle within the conditions that the DTC set.

Does the display indicate OK continuously?

--

Fault not present. Refer to Diagnostic Aids

Go to Step 3

3 | Does the display indicate Open? | -- | Go to Step 4 | Go to Step 6

4

1. Record the fluid life indexes, turn the key to LOCK and wait 30 seconds.
2. Disconnect PCM connector C2.
3. Turn the key ON.
4. Using DMM J 39200 measure the voltage to ground at PCM connector C2 terminal 27.

Is the voltage the same or more than the value specified?

10.0 volts

Go to Step 13

Go to Step 5

5

1. Turn the key to LOCK.
2. Disconnect EBTCM connector.
3. Measure the resistance between EBTCM connector terminal 34 and PCM connector C2 terminal 27.

Is the resistance the same or less than the value specified?

5 ohms

Go to Step 12

Go to Step 9

6

1. Turn the key to LOCK.
2. Disconnect the EBTCM connector.
3. Turn the key ON.

Does the Delivered Torque Driver parameter ever display Open/Short?

--

Go to Step 12

Go to Step 7

7

1. Record the fluid life indexes, turn the key to LOCK and wait 30 seconds.
2. Disconnect PCM connector C2.
3. Turn the key ON.
4. Measure the voltage to ground at PCM connector C2 terminal 27.

Is the voltage more than the value specified?

0.5 volts

Go to Step 10

Go to Step 8

8 | Using DMM J 39200 measure the resistance to ground at PCM connector C2 terminal 27. Is the resistance the same or more than the value specified? | 10K ohms | Go to Step 13 | Go to Step 11
9 | Repair the open in the Delivered Torque PWM Output circuit. Is the repair complete? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | --
10 | Repair the short to voltage on the Delivered Torque PWM Output circuit. Is the repair complete? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | --
11 | Repair the short to ground on the Delivered Torque PWM Output circuit. Is the repair complete? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | --

12

Fault is in EBTCM system.

1. Perform EBTCM diagnosis.
2. If fault is not found in EBTCM diagnosis, check terminal contact and if contact is okay, replace the EBTCM.

Is the repair and/or replacement complete?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

--

13

1. Check terminal contact at PCM connector C2 terminal 27.
2. Repair terminal contact if needed.

Was terminal contact repaired?

--

Go to Powertrain Control Module Diagnosis for Verify Repair

Go to Step 14

14 | Replace the PCM. Refer to PCM Replacement/Programming . Is the replacement complete? | -- | Go to Powertrain Control Module Diagnosis for Verify Repair | --