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Electronic Control System Gas Plus Engines – FAULT CODE 241

Vehicle Speed Sensor Circuit – Input Signal Lost

Overview

CODE REASON EFFECT
Fault Code: 241
PID: P84
SPN: 84
FMI: 2
LAMP: Amber
SRT: 

Vehicle Speed Sensor Circuit – data erratic, intermittent, or incorrect. The ECM lost the vehicle speed signal.

Engine speed limited to maximum engine speed without VSS parameter value. Cruise Control, gear-down protection, and road speed governor will not work.

Vehicle Speed Sensor Circuit
SMALL | MEDIUM | LARGE

Circuit Description

The vehicle speed sensor is an OEM-supplied sensor but can provide an input to the electronic control module (ECM) for added features such as road speed governing and cruise control.

Component Location

Refer to the OEM manual for location of this sensor. Usually, this sensor is installed in the tail shaft of the transmission.

Shop Talk

  • Disconnect the vehicle speed sensor connector that connects to the OEM speedometer, or trip recorder, and move the vehicle. If the fault goes inactive, there is probably electrical noise being fed into the vehicle speed sensor circuit from the OEM device.
  • Verify the vehicle speed sensor wires in the OEM harness are twisted pairs.
  • This sensor usually has one coil but can have two. Only one is used.
  • Vehicle speed can also be transmitted via the data link if the vehicle is utilizing the J1939. If no sensor is found but vehicle speed is being read, then it is likely being transmitted; so no vehicle speed sensor is used.

Cautions and Warnings

 CAUTION 

To reduce the possibility of damaging a new ECM, all other active fault codes must be investigated prior to replacing the ECM.
 CAUTION 

To reduce the possibility of pin and harness damage, use the following test leads when taking a measurement:
Part Number 3822758 – male Deutsch/AMP/Metri-Pack test lead
Part Number 3823996 – female Weather-Pack test lead.
 CAUTION 

To reduce the possibility of pin and harness damage, use the appropriate test lead when taking a
measurement.

Troubleshooting Steps

STEPS SPECIFICATIONS
STEP 1. Check the fault codes.  
  STEP 1A. Read the fault codes. Fault Code 241 active?
STEP 2. Check the vehicle speed sensor.  
  STEP 2A. Inspect the OEM harness and sensor connector pins. Dirty or damaged pins?
  STEP 2B. Read the fault codes. Fault Code 241 active?
  STEP 2C. Check the vehicle speed sensor for proper adjustment. 1/2 to 3/4 of a turn out from the gear?
  STEP 2D. Check the vehicle speed sensor resistance. 750 to 1500 ohms?
  STEP 2E. Check the vehicle speed sensor for a short circuit to ground. More than 100k ohms?
  STEP 2F. Check the vehicle speed sensor for a short circuit between coils. More than 100k ohms?
STEP 3. Check the engine harness.  
  STEP 3A. Inspect the engine harness and ECM connector pins. Dirty or damaged pins?
  STEP 3B. Read the fault codes. Fault Code 241 active?
  STEP 3C. Check for an open circuit. Less than 10 ohms?
  STEP 3D. Check for a short circuit to ground. More than 100k ohms?
  STEP 3E. Check for a short circuit from pin to pin. More than 100k ohms?
STEP 4. Clear the fault codes.  
  STEP 4A. Disable the fault code. Fault Code 241 inactive?
  STEP 4B. Clear the inactive fault codes. All fault codes cleared?

Guided Step 1 – Check the fault codes.

Guided Step 1A – Read the fault codes.

Conditions

  • Turn keyswitch ON
  • Connect the INSITE™ electronic service tool.

Fault Code 241 active?
YES NO
No Repair No Repair

Guided Step 2 – Check the vehicle speed sensor.

Guided Step 2A – Inspect the OEM harness and sensor connector pins.

Conditions

  • Turn keyswitch OFF
  • Disconnect the OEM harness from the vehicle speed sensor.

Action

  • Corroded pins
  • Bent or broken pins
  • Pushed back or expanded pins
  • Moisture in or on the connector
  • Missing or damaged connector seals
  • Dirt or debris in or on the connector pins.

Dirty or damaged pins?
YES NO

Repair or replace the OEM harness, or replace the sensor, whichever has the damaged pins.

  • Flush the dirt, debris, or moisture from the connector pins using electronic contact cleaner, Part Number 3824510.
  • Install the appropriate connector seal if it is damaged or missing.
  • Repair the OEM harness. Refer to the OEM troubleshooting and repair manual.
  • Replace the OEM harness. Refer to the OEM troubleshooting and repair manual.
  • Replace the sensor. Refer to Procedure 019-090 or 019-091.
 No Repair

Guided Step 2B – Read the fault codes.

Conditions

  • Connect all components
  • Turn keyswitch ON.

Action

  • Start the engine and let it idle for one minute.
  • Use INSITE™ electronic service tool to read the fault codes.

Fault Code 241 active?
YES NO
No Repair No Repair

Guided Step 2C – Check the vehicle speed sensor for proper adjustment.

Conditions

  • Turn keyswitch OFF
  • Disconnect the OEM harness from the vehicle speed sensor.

½ to ¾ of a turn out from the gear?
YES NO
No Repair

Adjust the sensor. Refer to Procedure 019-091.

Guided Step 2D – Check the vehicle speed sensor resistance.

Conditions

  • Turn keyswitch OFF
  • Disconnect the OEM harness from the vehicle speed sensor.

Action

  • Measure the resistance from the vehicle speed sensor (+) pin to the vehicle speed sensor (-) pin in the vehicle speed sensor connector, sensor side.
  • Repeat the resistance check in the second coil (if applicable).
SMALL | MEDIUM | LARGE

750 to 1500 ohms?
YES NO
No Repair

Guided Step 2E – Check the vehicle speed sensor for a short circuit to ground.

Conditions

  • Turn keyswitch OFF
  • Disconnect the OEM harness from the vehicle speed sensor
  • Make sure the sensor is installed.

Action

  • Measure the resistance from the vehicle speed sensor (+) pin in the vehicle speed sensor connector, sensor side, to engine block ground.
  • Repeat the short-circuit-to-ground check in the second coil (if applicable).
SMALL | MEDIUM | LARGE

More than 100k ohms?
YES NO
No Repair

Guided Step 2F – Check the vehicle speed sensor for a short circuit between coils.

Conditions

  • Turn keyswitch OFF
  • Disconnect the OEM harness from the vehicle speed sensor.

Action

  • Measure the resistance from the vehicle speed sensor (+) pin in the vehicle speed sensor connector to the vehicle speed sensor (+) pin in the second vehicle speed sensor connector, sensor side.
SMALL | MEDIUM | LARGE

More than 100k ohms?
YES NO
No Repair

Guided Step 3 – Check the engine harness.

Guided Step 3A – Inspect the engine harness and ECM connector pins.

Conditions

  • Turn keyswitch OFF
  • Disconnect engine harness connector 1 and connector 2 from the ECM.

Action

  • Corroded pins
  • Bent or broken pins
  • Pushed back or expanded pins
  • Moisture in or on the connector
  • Missing or damaged connector seals
  • Dirt or debris in or on the connector pins.

Dirty or damaged pins?
YES NO

Repair or replace the engine harness, or replace the ECM, whichever has the damaged pins.

  • Flush the dirt, debris, or moisture from the connector pins using electronic contact cleaner, Part Number 3824510.
  • Install the appropriate connector seal if it is damaged or missing.
  • Repair the engine harness. Refer to Procedure 019-204.
  • Replace the engine harness. Refer to Procedure 019-043.
  • Replace the ECM.
  • Call for pre-authorization. Refer to Procedure 019-031.
 No Repair

Guided Step 3B – Read the fault codes.

Conditions

  • Connect all components
  • Turn keyswitch ON.

Action

  • Start the engine and let it idle for one minute.
  • Use INSITE™ electronic service tool to read the fault codes.

Fault Code 241 active?
YES NO
No Repair No Repair

Guided Step 3C – Check for an open circuit.

Conditions

  • Turn keyswitch OFF
  • Disconnect the OEM harness from the vehicle speed sensor
  • Disconnect engine harness connector 2 from the ECM.

Action

  • Measure the resistance from the vehicle speed sensor (+) pin in the engine harness ECM connector to the vehicle speed sensor (+) pin in the sensor harness connector.
  • Measure the resistance from the vehicle speed sensor (-) pin in the engine harness ECM connector to the vehicle speed sensor (-) pin in the sensor harness connector.
SMALL | MEDIUM | LARGE

Less than 10 ohms?
YES NO
No Repair

Repair or replace the engine harness or OEM harness

  • Repair the engine harness. Refer to Procedure 019-202 or 019-204.
  • Replace the engine harness. Refer to Procedure 019-043.
  • Repair or replace the OEM harness. Refer to the OEM service manual.

Guided Step 3D – Check for a short circuit to ground.

Conditions

  • Turn keyswitch OFF
  • Disconnect engine harness connector 2 from the ECM.

Action

  • Measure the resistance from the vehicle speed sensor (+) pin in the engine harness ECM connector to engine block ground.
SMALL | MEDIUM | LARGE

More than 100k ohms?
YES NO
No Repair

Repair or replace the engine harness.

  • Repair the engine harness. Refer to Procedure 019-204.
  • Replace the engine harness. Refer to Procedure 019-043.
3E

 CAUTION 

To reduce the possibility of pin and harness damage, use the appropriate test lead when taking a
measurement.
Guided Step 3E – Check for a short circuit from pin to pin.

Conditions

  • Turn keyswitch OFF
  • Disconnect engine harness connector 1 and connector 2 from the ECM.

Action

  • Measure the resistance from the vehicle speed sensor (+) pin in engine harness ECM connector 2 to all other pins in the connector.
  • Measure the resistance from the vehicle speed sensor (-) pin in engine harness ECM connector 2 to all other pins in the connector.
  • Measure the resistance from the vehicle speed sensor (+) pin in engine harness ECM connector 2 to all pins in engine harness ECM connector 1.
  • Measure the resistance from the vehicle speed sensor (-) pin in engine harness ECM connector 2 to all pins in engine harness ECM connector 1.
SMALL | MEDIUM | LARGE

More than 100k ohms?
YES NO
No Repair

Repair or replace the engine harness.

  • Repair the engine harness. Refer to Procedure 019-204.
  • Replace the engine harness. Refer to Procedure 019-043.
4A

Guided Step 4 – Clear the fault codes.

Guided Step 4A – Disable the fault code.

Conditions

  • Connect all components
  • Turn keyswitch ON.

Action

  • Start the engine and let it idle for one minute.
  • Verify that Fault Code 241 is inactive.

Fault Code 241 inactive?
YES NO
No Repair

Troubleshooting procedures need to be repeated from the beginning. A failure mode will possibly have been detected.

Guided Step 4B – Clear the inactive fault codes.

Conditions

  • Connect all components
  • Turn keyswitch ON.

Action

  • Use INSITE™ electronic service tool to erase the inactive fault codes.

All fault codes cleared?
YES NO
No Repair

Troubleshoot any remaining active fault codes.
Repair complete
Appropriate troubleshooting charts
Last Modified:  28-Sep-2004
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Published by Jack

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