Checking Components And Wiring

Check the throttle unit and engine control module (ECM) connectors. Check for contact resistance and oxidation.

Check the resistance values of the potentiometers in the throttle unit and damper motor winding.

Replace the throttle unit if necessary.

Check the damper motor (+) and (-) cables. Check for an open-circuit. Check for a short-circuit to ground. Check for a short-circuit to supply voltage.

Check between:

• Engine control module (ECM) terminal #A74 (#B14) and throttle unit terminal #4
• Engine control module (ECM) terminal #A75 (#B15) and throttle unit terminal #1.

Also check the damper motor cables (+) and (-). Check for a short-circuit to each other.

Check that the shutter in the throttle unit is not blocked or sticking. Clean as necessary.

The throttle unit is damaged if the diagnostic trouble code (DTC) recurs.

Other information 

• see CONNECTING THE BREAKOUT BOX
• see SIGNAL SPECIFICATION, ENGINE CONTROL MODULE (ECM) (B5244S4) or SIGNAL SPECIFICATION, ENGINE CONTROL MODULE (ECM) (B5254T3)
• see COMPONENT SPECIFICATIONS
• see THROTTLE BODY, CLEANING (TURBO)
• see THROTTLE BODY
• see CONTENTS

Fig 2: Identifying Throttle Unit Connector Terminals

Courtesy of VOLVO CARS CORPORATION

Fig 3: Identifying Throttle Unit Connector Terminals

Courtesy of VOLVO CARS CORPORATION

Refer to INFORMATION